Toshiba TV29C90 problem; Image fades to black...

In alt.engineering.electrical Don Kelly <dhky@shaw.ca> wrote:
| ----------------------------
| "daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> wrote in message
| news:4828b193$0$7075$4c368faf@roadrunner.com...
|>
|> <phil-news-nospam@ipal.net> wrote in message
|> news:g0a7ts1t0c@news5.newsguy.com...
|>> In alt.engineering.electrical Michael Moroney
|>> <moroney@world.std.spaamtrap.com> wrote:
|>>
|>> | Are the load tap generators configured make-before-break?
|>> | Break-before-make would mean a (very short) power outage every
|>> activation
|>> | but make-before-break would mean a momentarily short-circuited winding
|>> and
|>> | the break would involve interrupting a large short circuit current.
|>>
|>> I wonder how much regulation could be managed through the use of variable
|>> leakage inductance in the transformer windings.
|>>
|>
|> I suppose you could, but increasing leakage inductance means you're
|> increasing losses aren't you? Just a percent or two on a unit rated for
|> 250 MVA can be too much to tolerate.
|>
|> daestrom
| -------------
| I don't see changing leakage inductance having much effect on losses ( a
| great effect on voltage regulation -likely all to the bad) but the problem
| is one of changing leakage inductance.
| Does this mean changing a gap in the core? Does it mean moving one winding
| with respect to another? In any case it does mean some fiddling with the
| core or winding.

The thought is to change the core in some way. Maybe that can be done in a
gradual way, as opposed to winding taps that have to be either BtM or MtB.


| This has been done for series lighting circuits where the load current was
| kept constant by using a transformer which balanced the forces between coils
| against a fixed weight. If the current changed the secondary coil moved so
| that there was more or less leakage. The units that I have seen were rather
| cumbersome.

I'm thinking more along the lines of a motor drive to move the coil, and
that be controlled by the same authority that would have controlled the
steppable taps.

--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
| Usenet from these places, find another Usenet provider ASAP. |
| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |

 

In alt.engineering.electrical Don Kelly <dhky@shaw.ca> wrote:
| ----------------------------
| "daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> wrote in message
| news:4828b193$0$7075$4c368faf@roadrunner.com...
|>
|> <phil-news-nospam@ipal.net> wrote in message
|> news:g0a7ts1t0c@news5.newsguy.com...
|>> In alt.engineering.electrical Michael Moroney
|>> <moroney@world.std.spaamtrap.com> wrote:
|>>
|>> | Are the load tap generators configured make-before-break?
|>> | Break-before-make would mean a (very short) power outage every
|>> activation
|>> | but make-before-break would mean a momentarily short-circuited winding
|>> and
|>> | the break would involve interrupting a large short circuit current.
|>>
|>> I wonder how much regulation could be managed through the use of variable
|>> leakage inductance in the transformer windings.
|>>
|>
|> I suppose you could, but increasing leakage inductance means you're
|> increasing losses aren't you? Just a percent or two on a unit rated for
|> 250 MVA can be too much to tolerate.
|>
|> daestrom
| -------------
| I don't see changing leakage inductance having much effect on losses ( a
| great effect on voltage regulation -likely all to the bad) but the problem
| is one of changing leakage inductance.
| Does this mean changing a gap in the core? Does it mean moving one winding
| with respect to another? In any case it does mean some fiddling with the
| core or winding.

The thought is to change the core in some way. Maybe that can be done in a
gradual way, as opposed to winding taps that have to be either BtM or MtB.


| This has been done for series lighting circuits where the load current was
| kept constant by using a transformer which balanced the forces between coils
| against a fixed weight. If the current changed the secondary coil moved so
| that there was more or less leakage. The units that I have seen were rather
| cumbersome.

I'm thinking more along the lines of a motor drive to move the coil, and
that be controlled by the same authority that would have controlled the
steppable taps.

--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
| Usenet from these places, find another Usenet provider ASAP. |
| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |

 

[bz]

dave@hurtle.com wrote in news:0c3c37fc-f6f1-4f44-9b9e-a93cdb18f78b@
27g2000hsf.googlegroups.com:

OK. I popped the cover off the control panel outside to have a look.
At some point the control module was replaced with a Lee Dan PK-543.
Well it looks like they still make them if this is the problem. The
only other possible problem could be the transformer which kicks the
voltage down to 16 VAC to run the module.

Now here's a dumb question. Where would this transformer be located?
It's not behind the control panel outside. I looked around the
basement by the circuit breakers/cable/phone lines and couldn't find
it there either. Any suggestions where to look?

Doorbell transformers are often located in the attic.







--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+ser@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap

 

[bz]

dave@hurtle.com wrote in news:0c3c37fc-f6f1-4f44-9b9e-a93cdb18f78b@
27g2000hsf.googlegroups.com:

OK. I popped the cover off the control panel outside to have a look.
At some point the control module was replaced with a Lee Dan PK-543.
Well it looks like they still make them if this is the problem. The
only other possible problem could be the transformer which kicks the
voltage down to 16 VAC to run the module.

Now here's a dumb question. Where would this transformer be located?
It's not behind the control panel outside. I looked around the
basement by the circuit breakers/cable/phone lines and couldn't find
it there either. Any suggestions where to look?

Doorbell transformers are often located in the attic.







--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+ser@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap

 

In alt.engineering.electrical Don Kelly <dhky@shaw.ca> wrote:

| Yes -you are shorting a part of the winding but the switching is a bit more
| complex than that so that short circuit currents are limited to reasonable
| values. It is a multistep operation with reactor switching. On-load tap
| changers are expensive and are generally limited to applications where this
| is absolutely needed (I have seen one where the tap changer was nearly as
| large as the transformer).

I was thinking of what I might do to get some fine voltage control within a
very limited range around 120 volts. The obvious option was a 0-140 volt
variable transformer. But I wanted to make sure I had a setup that could
be better limited, for example, to not allow an accidental too low voltage.
I also didn't want to run all the power through the variable. So what I
was going to do was get a smaller variable transformer, and two buck-boost
transformers. One transformer would be wired 120->16 in buck mode to drop
the voltage down to 104. The other transformer would be wired 120->24 and
supplied via the 0-140 variable transformer, giving me a 0-28 variable boost.
The end result is 104-132 over the full range of variable transformer control
(assuming the boost transformer has no issues with being overfed at 140V).

So I might envision a transformer where the taps can be part of a boost
transformer added to the main transformer. The first buck transformer in
my above example would not be needed because the main transformer would be
designed with a 1st secondary at the lowest voltage of the adjustable range.
A 2nd secondary on the same main transformer would have the adjustable taps
and it would feed a separate boost transformer which has a secondary wired
in series with the 1st secondary of the main. So the taps would only be
dealing directly with a fraction of the power (assuming there is no back
feed issue involved) based on the needed adjustment range.

--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
| Usenet from these places, find another Usenet provider ASAP. |
| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |

 

In alt.engineering.electrical Thomas Tornblom <thomas@hax.se> wrote:

| Residential power in Norway is normally 230V three phase btw, instead
| of 400V three phase. Their 230V outlets are two phase and ground
| instead of one phase, neutral and ground. Their three phase outlets
| therefore are blue instead of red and have four prongs instead of five.

Is this the system where the voltage is 133 volts relative to ground and 230
volts between phases (and formerly 127 volts relative to ground and 220 volts
between phases)?

If they still use that system, then I'm interested in buying a UPS designed
for that. But it is my understanding it is phased out in cities and hard to
find anymore in rural locations.

--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
| Usenet from these places, find another Usenet provider ASAP. |
| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |

 

In alt.engineering.electrical Ian Jackson <ianREMOVETHISjackson@g3ohx.demon.co.uk> wrote:
| In message <x0hcd24e0k.fsf@Hax.SE>, Thomas Tornblom <thomas@Hax.SE>
| writes
|>"Michael A. Terrell" <mike.terrell@earthlink.net> writes:
|>
|>> Thomas Tornblom wrote:
|>>>
|>>> "Michael A. Terrell" <mike.terrell@earthlink.net> writes:
|>>>
|>>> > maarten@panic.xx.tudelft.nl wrote:
|>>> >>
|>>> >> In sci.electronics.repair jakdedert <jakdedert@bellsouth.net> wrote:
|>>> >> > I'm a little confused about a 230 volt circuit. In what part of the
|>>> >> > world does the utility supply 230v?
|>>> >>
|>>> >> Continental Europe used to have 220 volts (before that it was 127
|>>> >>volts in
|>>> >> some places), the UK used to have 240 volts. Nowadays, the common voltage
|>>> >> is 230 volts -10% +6%.
|>>> >
|>>> >
|>>> > In other words, nothing has changed. They just wrote sloppier specs.
|>>>
|>>> It has changed, the voltage is now close to 230V, at least in Sweden.
|>>>
|>>> I guess the sloppiness was specified to allow a gradual switch from
|>>> 220/240 to 230 and still be within spec.
|>>>
|>> Do the math. The specifications allow continued use of the old
|>> standard n each country.
|>
|>If you read my comment you will see that I agree that the new spec
|>covers the old voltages. I do not agree with your statement that
|>"nothing has changed". We had 220V before and we now have 230V, so the
|>actual voltage has definitely changed.
|
| In the UK, we had 240V. We now have err..... 240V.
| There may be places where it really has been reduced to 230V, but I've
| never been anywhere where I had occasion to measure the mains voltage,
| and didn't get around 240V - certainly not sufficiently different for
| you to notice the difference.

What I have heard is that teh distribution system is not changing, but new
service installations will be supplied with 230V unless 240V is specifically
requested ... after some point in time that may not have come, yet. What
I heard is they don't expect to have all of UK changed over for many decades,
and maybe even a century or so.

--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
| Usenet from these places, find another Usenet provider ASAP. |
| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |

 

[dBc]

Greetings Bill..

Regarding:
"I am skilled in electronics and do have experience with HV systems, I
just do not know where to being looking...."

I suspect that you meant BEGIN looking..

First and foremost, this has nothing to do with an EEPROM or a
microprocessor.

Interesting.. One of the first things almost any school teaches (trade
school, 2 year junior colleges or even the universities) is about
video systems. In regards to electrical circuits and theory, it's a
good place to learn about oscillators, amplifiers, deflection both
vertical and horizontal, power supplies etc. Even though our video
sets are changing, the theory behind the above circuits still
applies..

As illustrated in many a fix-it-yourself softbound books still on the
shelf regarding TV repair, this is a vertical oscillator/amplifier
issue. Now days, both are usually in an integrated circuit with
polarized electrolytic capacitors hanging off the IC. Since the IC
tends to get rather hot in many installations, an initial inspection
of the IC is a good idea. I've recently fixed a JVC with intermittent
vertical deflection issues by merely sucking up the old solder
(Soldapullt) and re-soldering it with a clean soldering job on all
pins, then removing the residual flux with alcohol. The TV is still
working years later now.

In addition, I've got a 25" stereo color TV that was given to me by
someone at work with the same symptoms that you describe, bright
horizontal line (in the middle of the CRT) with no vertical
deflection - sound is A-OK. It seems that the previous families kids
liked to push all the front panel buttons real quick - including the
on/off button - unfortunately.. The first thing I did was call
Thompson and order the schematics for the TV. Sure enough, the
vertical oscillator/amplifier IC was shot. Once replaced, the video
folded over at the top of the now full deflected video image. Why the
folded over image, defective polarized electrolytic capacitors. As I
seem to recall, there's usually a 33ufd capacitor (amongst a few
others) that are highly suspect. How to determine for sure, an ESR
(Equivalent Series Resistance) checker will determine in two shakes
which electrolytics are bad. Since the electrolytics are relatively
inexpensive, you can always shotgun with about 5 or 6 around the IC,
but - obviously, measuring for the defective component(s) is always
preferred. Once the IC and the capacitors were replaced, I've been
enjoying that free stereo TV ever since. The picture is now beautiful
and, prior to doing the 'fix,' I cleaned out the cabinet completely
and got rid of the dust & spiders. They had put it in the garage on
the floor..

Cheers,
Mr. Mentor



"Bill" <billp@rhondasworld.com> wrote in message
newsan.2008.05.12.18.24.56.893717@rhondasworld.com...
|I have an RCA g35302wk that has been a great TV for a number of
years.
| Recently it started doing this funky thing where the picture would
| collapse and you are left with a thin horizontal line all the way
across
| the screen. The line is very bright, and the television still has
audio
| when this happens. At first if you turned the TV off for a few
minutes
| then back on the picture would clear up and it would be ok for a
random
| amount of time, between about 1/2 hour and 2 hours. One morning
though it
| went into the collapsed state and has been stuck there ever since. I
found
| very little repair infor for this TV on the internet, one page said
to
| replace U3101 (210736), U3200 (209956) and microprocessor. But I
dont
| think that is causing this issue. Can anyone give me any tips on
anything
| else that may be causing this picture collapse? I did replace the
power
| supply about 2 years ago. I am skilled in electronics and do have
| experience with HV systems, I just do not know where to being
looking. I
| know the NEW HD world is coming up, but I would love to keep this TV
going
| if it can be fixed without much trouble.
|
| Thanks in Advance,
| Bill
|
|

 

In alt.engineering.electrical Don Kelly <dhky@shaw.ca> wrote:

| Yes -you are shorting a part of the winding but the switching is a bit more
| complex than that so that short circuit currents are limited to reasonable
| values. It is a multistep operation with reactor switching. On-load tap
| changers are expensive and are generally limited to applications where this
| is absolutely needed (I have seen one where the tap changer was nearly as
| large as the transformer).

What about multiple parallel transformers, or at least multiple parallel
windings on the same core (on whichever side the tapping is to be done),
where the taps are stepped incrementally on each winding? Instead of a
shorted winding segment, you'd have windings of differing voltage in
parallel as each of the windings change their taps one at a time.

--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
| Usenet from these places, find another Usenet provider ASAP. |
| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |

 

[dBc]

Conundrum..

Ouch! GOOD LUCK!

And just think, folks make fun, now days, of people with CRT based
sets. At least you've got a chance repairing them relative to what
you're contemplating going through!

I'll believe I'll stick to my free 25" stereo (CRT) TV set that was
given to me with a vertical oscillator/amplifier & a few electrolytics
that needed replacing.. While it certainly won't look as impressive as
a new plasma based set, it's certainly not as expensive and sure
significantly less work and cheaper to repair. In addition, probably
doesn't cause quite as much RFI as most plasma sets tend to do!

Cheers,
Mr. Mentor


"conundrum" <testing_h@yahoo.com> wrote in message
news:2ba943fd-c811-432b-94a0-f1721e93e737@d45g2000hsc.googlegroups.com...
| Hi all.
|
| I have two of these beasties, both JVC 42" plasmas made at about the
| same time.
|
| Unfortunately, one has a burned out PDP (has big black line on the
| screen about 1/3 the way across and halfway down the screen) and the
| other has an apparently fried controller board but the PDP looks
fine.
|
| I've got as far as determining that the base boards are not
| mechanically compatible but they do use the same PDP, with
essentially
| the same pinout and specifications.
|
| I can't seem to work out how to separate the PDP and uber-fragile
| flexi cables with embedded LSI HV chips from the base plate with its
| incorrect screw locations, undid about 24 screws and no go
|
| Has anyone even attempted such a mammoth task? It seems feasible
(the
| LCD I modded is easy by comparison)
|
| Thanks in advance.
| -A
|
| "Bother" said Pooh, as Darth Maul 'sabred him in twain...

 

[dBc]

Conundrum..

Ouch! GOOD LUCK!

And just think, folks make fun, now days, of people with CRT based
sets. At least you've got a chance repairing them relative to what
you're contemplating going through!

I'll believe I'll stick to my free 25" stereo (CRT) TV set that was
given to me with a vertical oscillator/amplifier & a few electrolytics
that needed replacing.. While it certainly won't look as impressive as
a new plasma based set, it's certainly not as expensive and sure
significantly less work and cheaper to repair. In addition, probably
doesn't cause quite as much RFI as most plasma sets tend to do!

Cheers,
Mr. Mentor


"conundrum" <testing_h@yahoo.com> wrote in message
news:2ba943fd-c811-432b-94a0-f1721e93e737@d45g2000hsc.googlegroups.com...
| Hi all.
|
| I have two of these beasties, both JVC 42" plasmas made at about the
| same time.
|
| Unfortunately, one has a burned out PDP (has big black line on the
| screen about 1/3 the way across and halfway down the screen) and the
| other has an apparently fried controller board but the PDP looks
fine.
|
| I've got as far as determining that the base boards are not
| mechanically compatible but they do use the same PDP, with
essentially
| the same pinout and specifications.
|
| I can't seem to work out how to separate the PDP and uber-fragile
| flexi cables with embedded LSI HV chips from the base plate with its
| incorrect screw locations, undid about 24 screws and no go
|
| Has anyone even attempted such a mammoth task? It seems feasible
(the
| LCD I modded is easy by comparison)
|
| Thanks in advance.
| -A
|
| "Bother" said Pooh, as Darth Maul 'sabred him in twain...

 

[dBc]

Greetings Jerry..

Interesting situation but not unlike what has been going on for years
in the south SF Bay Area (San Jose). Sutro Tower is towards SF for
about 50 miles while KNTV (Channel 11) is the opposite direction right
in San Jose - behind you. For several years (many years ago now), KNTV
sold a small 2 element antenna that you could mount on your TV mast
and point the opposite direction to your normal TV antenna. It worked
like a champ and got rid of what Dick calls:

Reference:
"Although I mentioned that you "could" combine the two antennas into
one lead, the reason you may not want to is something called
"ghosting." The two antennas will be receiving the same stations,
although not from the same direction."

This is the laymen's term for multipath interference. Two paths
instead of a straight line point A => B. That reflection comes in a
bit slower than the original signal path, thus the delay results in a
"ghosting" affect. This can also be quite noticeable on FM reception.
Indeed, as a radio amateur, we can actually use it to our advantage by
reflecting our signals off natural points!

Although we tended to use 300 ohm twin lead back in those days, you
should be fine with 75 ohm coax. As Dick has mentioned, if you want
the trouble and expense of two pieces of coax to run (really
un-needed) go for it. Personally, I would either get an inexpensive
rotator (programmable now days) with a remote for it and put up a nice
single array OR go with two antennas and run the coax between them. I
should also mention, a large number of apartment complexes across this
country are doing the two antenna (or more) with a single lead in
routine.

Cheers,
Mr. Mentor

Jerry, be careful listing your actual e-mail address on Usenet, there
are folks out here that you REALLY don't want e-mailing you! Just put
in something bogus, it will take it! Notice what mine is...



"Jerry" <jerry_maple@hotmail.com> wrote in message
news:3e698643-6df7-40b4-8141-039f12229cd2@j33g2000pri.googlegroups.com...
|I have been looking at the post-February-2009 TV situation for my
| summer cabin, which is about 20 miles outside of Flagstaff AZ. Being
| mountainous, and semi-rural, it appears that there will still be a
lot
| of analog repeater signals, even after the digital switchover date.
| Specifically, the TVFool website indicates that there will be 4 or 5
| digital signals coming from Flagstaff, an azimuth of 56 degrees from
| my location; and maybe a dozen analog repeater signals that I am
| receiving now, mostly coming from a place called Mingus Mountain, an
| azimuth of 228 degrees from my location.
|
| Not really interested in using an antenna rotator. Did enough
Googling
| to see that stacking antennas might be my answer, point one at
| Flagstaff and the other at Mingus.
|
| Can I just connect the antenna leads together, or do I need
something
| to combine the signals from the separate antennas?
|
| Any other hints on how to maximize my reception?
|
| Also, the digital converter box I bought does not have analog
| passthrough. When I got it, I thought even the repeater stations
would
| be going digital in February, I didn't know that they would be
staying
| analog for some unknown amount of time. So, I guess I need to be set
| up to handle both signals, analog and digital.
|
| I was thinking to do the following to switch between analog and
| digital reception. Connect the antenna lead from the roof to the
input
| of an A-B switch (3 bucks at Frys Electronics). Connect the A output
| of the switch to the RF input on the TV, use normal TV analog tuner
| for the analog repeater stations. Connect the B output of the switch
| to the RF input of the digital converter, connect the AV outputs of
| the converter to the AV inputs of the TV, set the TV to AV In. Is
that
| going to work?
|
| Thanks in advance for any helpful hints,
| Jerry

 

[dBc]

Greetings Jerry..

Interesting situation but not unlike what has been going on for years
in the south SF Bay Area (San Jose). Sutro Tower is towards SF for
about 50 miles while KNTV (Channel 11) is the opposite direction right
in San Jose - behind you. For several years (many years ago now), KNTV
sold a small 2 element antenna that you could mount on your TV mast
and point the opposite direction to your normal TV antenna. It worked
like a champ and got rid of what Dick calls:

Reference:
"Although I mentioned that you "could" combine the two antennas into
one lead, the reason you may not want to is something called
"ghosting." The two antennas will be receiving the same stations,
although not from the same direction."

This is the laymen's term for multipath interference. Two paths
instead of a straight line point A => B. That reflection comes in a
bit slower than the original signal path, thus the delay results in a
"ghosting" affect. This can also be quite noticeable on FM reception.
Indeed, as a radio amateur, we can actually use it to our advantage by
reflecting our signals off natural points!

Although we tended to use 300 ohm twin lead back in those days, you
should be fine with 75 ohm coax. As Dick has mentioned, if you want
the trouble and expense of two pieces of coax to run (really
un-needed) go for it. Personally, I would either get an inexpensive
rotator (programmable now days) with a remote for it and put up a nice
single array OR go with two antennas and run the coax between them. I
should also mention, a large number of apartment complexes across this
country are doing the two antenna (or more) with a single lead in
routine.

Cheers,
Mr. Mentor

Jerry, be careful listing your actual e-mail address on Usenet, there
are folks out here that you REALLY don't want e-mailing you! Just put
in something bogus, it will take it! Notice what mine is...



"Jerry" <jerry_maple@hotmail.com> wrote in message
news:3e698643-6df7-40b4-8141-039f12229cd2@j33g2000pri.googlegroups.com...
|I have been looking at the post-February-2009 TV situation for my
| summer cabin, which is about 20 miles outside of Flagstaff AZ. Being
| mountainous, and semi-rural, it appears that there will still be a
lot
| of analog repeater signals, even after the digital switchover date.
| Specifically, the TVFool website indicates that there will be 4 or 5
| digital signals coming from Flagstaff, an azimuth of 56 degrees from
| my location; and maybe a dozen analog repeater signals that I am
| receiving now, mostly coming from a place called Mingus Mountain, an
| azimuth of 228 degrees from my location.
|
| Not really interested in using an antenna rotator. Did enough
Googling
| to see that stacking antennas might be my answer, point one at
| Flagstaff and the other at Mingus.
|
| Can I just connect the antenna leads together, or do I need
something
| to combine the signals from the separate antennas?
|
| Any other hints on how to maximize my reception?
|
| Also, the digital converter box I bought does not have analog
| passthrough. When I got it, I thought even the repeater stations
would
| be going digital in February, I didn't know that they would be
staying
| analog for some unknown amount of time. So, I guess I need to be set
| up to handle both signals, analog and digital.
|
| I was thinking to do the following to switch between analog and
| digital reception. Connect the antenna lead from the roof to the
input
| of an A-B switch (3 bucks at Frys Electronics). Connect the A output
| of the switch to the RF input on the TV, use normal TV analog tuner
| for the analog repeater stations. Connect the B output of the switch
| to the RF input of the digital converter, connect the AV outputs of
| the converter to the AV inputs of the TV, set the TV to AV In. Is
that
| going to work?
|
| Thanks in advance for any helpful hints,
| Jerry

 

[Arfa Daily]

"conundrum" <testing_h@yahoo.com> wrote in message
news:2ba943fd-c811-432b-94a0-f1721e93e737@d45g2000hsc.googlegroups.com...
| Hi all.
|
| I have two of these beasties, both JVC 42" plasmas made at about the
| same time.
|
| Unfortunately, one has a burned out PDP (has big black line on the
| screen about 1/3 the way across and halfway down the screen) and the
| other has an apparently fried controller board but the PDP looks
fine.
|
| I've got as far as determining that the base boards are not
| mechanically compatible but they do use the same PDP, with
essentially
| the same pinout and specifications.
|
| I can't seem to work out how to separate the PDP and uber-fragile
| flexi cables with embedded LSI HV chips from the base plate with its
| incorrect screw locations, undid about 24 screws and no go
|
| Has anyone even attempted such a mammoth task? It seems feasible
(the
| LCD I modded is easy by comparison)
|
| Thanks in advance.
| -A
|
| "Bother" said Pooh, as Darth Maul 'sabred him in twain...

"dBc" <not_necessary@thanks.com> wrote in message
news:uVvWj.102$oJ4.3499647@petpeeve.ziplink.net...

Conundrum..

Ouch! GOOD LUCK!

And just think, folks make fun, now days, of people with CRT based
sets. At least you've got a chance repairing them relative to what
you're contemplating going through!

I'll believe I'll stick to my free 25" stereo (CRT) TV set that was
given to me with a vertical oscillator/amplifier & a few electrolytics
that needed replacing.. While it certainly won't look as impressive as
a new plasma based set, it's certainly not as expensive and sure
significantly less work and cheaper to repair. In addition, probably
doesn't cause quite as much RFI as most plasma sets tend to do!

Cheers,
Mr. Mentor

Plasma and LCD sets only look impressive to your neighbours who haven't got
one, or if you see them in shops running on a Blu Ray HD DVD player.
Otherwise, compared to a good (or even mediocre) CRT set, the picture they
produce, is crap ...

Arfa

 

[Arfa Daily]

"Max" <maxg70@surewest.net> wrote in message
news:hb6dnebEeZuhqrfVnZ2dnUVZ_sDinZ2d@posted.surewest...

sstepanov@gmail.com wrote:
Hello! I have a Philips 30PF9946D/37 30" LCD that no longer turns on.
Upon pressing the power button, the status LED goes from green to
amber then to red.

Is this a common problem with these?

Thank you!
Could be ps board.

It's a common problem with all LCD TV sets. First, try unplugging the
display panel's backlight inverter board. It is very common for these to
fail and cause the set to revert to standby. Otherwise, it's most likely
that the PSU itself is faulty - also very common.

Examine it *very* carefully for bulged electrolytics on the secondary side.
Note that these may be 'hiding' under bits of heatsink, so look carefully.
Also, check all large and heatsink-mounted devices, for bad (lead-free !!)
joints, which is another common cause of your described symptoms. Other than
this, you're a bit 'on your own' with LCD sets. There are other possible
causes, such as bad sound output chips, but if you really do have a power
supply problem that's not one of the things described, then you will
struggle to get to the bottom of it without schematics, and an intimate
knowledge of switchmode power supplies. These LCD ones are infested with
monitoring circuitry for output voltages and over-current conditions, and
they all work on the standby supply, so if *any* unexpected condition is
detected either at startup, or during use, the standby supply is momentarily
stopped, which causes the system control micro to reset back to its 'sleep'
condition, removing the 'power on' signal to the power supply. Depending on
the set, that may then be an end to it until you try to bring it out of
standby again, or it may just keep trying on its own, causing a flashing
power light.

If you can prove which board is causing the trouble, you might want to
consider just replacing that board. PSUs and inverters for many sets, can be
found astonishlingly cheap on the 'net and e-bay sometimes.

Arfa

 

[Tzortzakakis Dimitrios]

Ď <phil-news-nospam@ipal.net> Ýăńářĺ óôď ěŢíőěá
news:g0dfd301f8f@news3.newsguy.com...

In alt.engineering.electrical Tzortzakakis Dimitrios <noone@nospam.void
wrote:
|
| ? <phil-news-nospam@ipal.net> ?????? ??? ??????
| news:g0a7lq0t0c@news5.newsguy.com...
|> In alt.engineering.electrical Tzortzakakis Dimitrios
noone@nospam.void
|> wrote:
|
|> | A shame that Tesla won the infamous "battle" and we don't have DC:-()
|> But
|> | then, we would be having a power plant at each neighborhood, instead
of
|> the
|> | 300 MW ones.
|
|> And the latter make easy terrorism targets, too.
|
| I cross my fingers that terrorists get no electrical engineering
degree:0

I suspect quite many already have them. Many have degrees in a lot of
other
things like chemistry and physics. Some even have doctoral level degrees.


|> | I know, I know, my answer was a bit provocative And of course
there
|> are
|> | DC regulators.... You're talking about DC generators;the one a 300 MW
|> uses
|> | for excitation is 220 V, 1000 A DC and probably shunt field. I have
seen
|> | here in some machine shops the old type welding generator, which is a
3
|> | phase induction motor coupled to (usually) a compound field DC
|> generator,
|> | which provides the welding current. The modern ones are, maybe, not
|> larger
|> | than a shoe box and powered by a higher wattage 230 V 16 A
receptacle.
|> | (Usual receptacles are 230 V 10 A;16 A for washing machines, dryers
and
|> the
|> | like).
|
|> You don't use 400 V for anything heavy duty like an oven?
|
| Yep. All ovens sold in EU are wired for 3 phase, 400 V with neutral (and
| earth, goes without saying). Just if you connect it on 1 phase (as
usually)
| you use a bridge, and connect all L1-L2-L3 to the one and only hot. 230
V is
| powerful enough for almost everything in a house, only large
airconditioners
| are 3 phase, and all industrial motors, even if they are 1HP (

That means each element individually runs on 230 V and they just divided
them
up in three approximately equal sections, or use triple elements for each
type
of use.

How many things that have just ONE (large) element would have it available
in
both 230 V and 400 V versions?

Professional washing machines. One of my very first days 'in the field' was

to connect some of them. They have a large heating element, you can connect
it single phase, or 3 phase, it just heats up faster (of course) when you
connect it 3 phase. (they have a single phase motor, so it works also in
pure 230 V).


--
Tzortzakakis Dimitrios
major in electrical engineering
mechanized infantry reservist
hordad AT otenet DOT gr
NB:I killfile googlegroups.

 

[Tzortzakakis Dimitrios]

Ď <phil-news-nospam@ipal.net> Ýăńářĺ óôď ěŢíőěá
news:g0dfd301f8f@news3.newsguy.com...

In alt.engineering.electrical Tzortzakakis Dimitrios <noone@nospam.void
wrote:
|
| ? <phil-news-nospam@ipal.net> ?????? ??? ??????
| news:g0a7lq0t0c@news5.newsguy.com...
|> In alt.engineering.electrical Tzortzakakis Dimitrios
noone@nospam.void
|> wrote:
|
|> | A shame that Tesla won the infamous "battle" and we don't have DC:-()
|> But
|> | then, we would be having a power plant at each neighborhood, instead
of
|> the
|> | 300 MW ones.
|
|> And the latter make easy terrorism targets, too.
|
| I cross my fingers that terrorists get no electrical engineering
degree:0

I suspect quite many already have them. Many have degrees in a lot of
other
things like chemistry and physics. Some even have doctoral level degrees.


|> | I know, I know, my answer was a bit provocative And of course
there
|> are
|> | DC regulators.... You're talking about DC generators;the one a 300 MW
|> uses
|> | for excitation is 220 V, 1000 A DC and probably shunt field. I have
seen
|> | here in some machine shops the old type welding generator, which is a
3
|> | phase induction motor coupled to (usually) a compound field DC
|> generator,
|> | which provides the welding current. The modern ones are, maybe, not
|> larger
|> | than a shoe box and powered by a higher wattage 230 V 16 A
receptacle.
|> | (Usual receptacles are 230 V 10 A;16 A for washing machines, dryers
and
|> the
|> | like).
|
|> You don't use 400 V for anything heavy duty like an oven?
|
| Yep. All ovens sold in EU are wired for 3 phase, 400 V with neutral (and
| earth, goes without saying). Just if you connect it on 1 phase (as
usually)
| you use a bridge, and connect all L1-L2-L3 to the one and only hot. 230
V is
| powerful enough for almost everything in a house, only large
airconditioners
| are 3 phase, and all industrial motors, even if they are 1HP (

That means each element individually runs on 230 V and they just divided
them
up in three approximately equal sections, or use triple elements for each
type
of use.

How many things that have just ONE (large) element would have it available
in
both 230 V and 400 V versions?

Professional washing machines. One of my very first days 'in the field' was

to connect some of them. They have a large heating element, you can connect
it single phase, or 3 phase, it just heats up faster (of course) when you
connect it 3 phase. (they have a single phase motor, so it works also in
pure 230 V).


--
Tzortzakakis Dimitrios
major in electrical engineering
mechanized infantry reservist
hordad AT otenet DOT gr
NB:I killfile googlegroups.

 

[Tzortzakakis Dimitrios]

? "daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> ?????? ??? ??????
news:4829fd51$0$30162$4c368faf@roadrunner.com...

"Tzortzakakis Dimitrios" <noone@nospam.void> wrote in message
news:g0c3sa$902$1@mouse.otenet.gr...

? "daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> ?????? ??? ??????
news:4828b130$0$7047$4c368faf@roadrunner.com...

"Michael Moroney" <moroney@world.std.spaamtrap.com> wrote in message
news:g0a1o5$bcq$1@pcls6.std.com...
"daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> writes:


P.S. In the US, a 'tap-changer' may be built for either for unloaded
or
loaded operation. The 'unloaded' type can not be stepped to another
tap
while there is load on the unit (although it can still be energized).
It's
switch contacts cannot interrupt load though, so if you try to move it
while
loaded, you can burn up the tap-changer. The classic
'load-tap-changer' is
actually several switches that are controlled in a precise sequence to
shift
the load from one tap of the transformer to another while not
interrupting
the load current.

P.P.S. Load tap changers typically have a significant time-delay built
into
the controls so they do not 'hunt' or respond to short drops in voltage
such
as starting a large load. 15 seconds to several minutes is typical.
So
even with load-tap-changers, starting a single load that is a high
percentage of the system capacity will *still* result in a voltage dip.

Are the load tap generators configured make-before-break?
Break-before-make would mean a (very short) power outage every
activation
but make-before-break would mean a momentarily short-circuited winding
and
the break would involve interrupting a large short circuit current.

Certainly modern ones likely use thyristors and zero crossing
detectors.


I figured someone would 'bite'

Typical large power load-tap-changers have a primary winding and two
secondaries.
You mean a secondary and a tetriary? The transformer for the hotel load
of a 300 MW unit is powered directly from the turbo alternator (21 kV)
and has a secondary of 6.6 kV and a tetriary of again 6.6 kV. This is
done because it has wye-wye-wye connection (IIRC). The hotel load of such
a unit is 10%, also 30 MW, including 7 brown coal mills. Typical size of
a 6.6 kV motor is 1 MW.
One secondary produces about 100% of 'rated' secondary voltage. The
second secondary produces about 15% to 20% of the rated voltage, but has
numerous taps from end to end, about 2.5% 'steps'. (for a total of about
eight taps). The cental tap of the boost/buck winding is tied to one end
of the main secondary. The boost/buck can be used to step from 90% to
110% of the 'design' output. I suppose some can step over a wider range,
but I haven't run across them.

*TWO* rotary switches have each tap tied to one of the positions of each
rotory switch, and each 'wiper' is tied to single heavier contacts that
are opened in the operating sequence. The output side of these two
interrupting contacts are tied to each end of a large center-tapped
inductor.

So, normally both rotary switches are aligned to the same transformer
tap, both interrupting contacts are shut, and load current flows from
the boost/buck winding tap, splits and flows through both rotary
switches, both interrupting contacts, enters both ends of the inductor
and out the inductor center tap. Because the current flows into both
ends of the inductor and the mutual inductance of the two parts cancel,
there is little voltage drop in the inductor.

Begin step sequence:
1) Open one interrupting contactor. Now load current doubles through
half the inductor and is zero in the other half, so the voltage drop
across the inductor actually makes output voltage drop, even if trying
to step 'up'.
2) Move associated rotary switch to next step of transformer bank.
3) Close interrupting contactor. Now, the two rotary switches are
across different taps. The inductor prevents a excessive current,
otherwise you have a direct short of the two winding taps. Some tap
changers can stop at this point and are called 'half-step' units.
Obviously, the inductor has to be rated for sustained operation across a
step of the boost/buck winding plus load current in order to survive
sustained 'half step' operation.
4) But for tap changers that can't operate 'half-step', the sequence
continues. And opens the other interrupting contactor. Now the other
half of the inductor has full load current.
5) Move second rotary switch to next step (now both switches are on the
new step)
6) Close the second interrupting contactor. You're back in the initial
configuration, but with both rotary switches on a new transformer tap.
Quite the same principle is done with diesel locomotives and is called
diesel-electric transmission, and also in pure electric locomotives
(E-Lok in german, for Elektrische Lokomotive). The diesel engine,
2-stroke and usually 600 to 900 rpm at full throttle, is coupled to a
generator. The generator has small windings, connected in series for the
last notch, higher voltage and relatively smaller current, and in
parallel for start, higher amperage and smaller voltage. The traction
motors are directly coupled on the wheel shaft, and are air cooled. An
E-Lok has a trasformer, with the primary directly supplied by the
cetenary, 15 kV 16 2/3 Hz in Germany, and 25 kV 50 Hz in Greece, The
secondary uses the same principle. The typical size of a traction motor
is 1 MW, 4 (one each shaft) and maximum voltage 700 volts, and are series
wound motors with special construction to operate at 16 2/3 Hz (or 50 Hz
with today's technology). Typical power of a diesel locomotive is 2850
HP, while an electric is 6000 HP. with 1500 HP at each shaft, also ~1MW.
There is a heavy duty 12,000 HP diesel engine in USA(with 6 shafts, also
2000 HP at each shaft). The high speed ICE train (InterCityExpress) in
germany is 13,000 HP, has a normal travelling speed of 200 km/h, 2
locomotives, 3-phase induction motors, electronic drive.

In US, diesel-electric used to always be DC machines, but modern ones are
now AC generators with thyristers to regulate the power flow to the
traction motors. Traction motors are still DC however to allow for their
use in dynamic braking.

I suppose in Europe the better way to go would be regenerative braking,
putting the braking power back into the overhead line, but that would need
a static inverter. Probably the transformer secondary has a four-quadrant
converter to allow reversal of power flow ??

This is for sure in ICE, where they get 15 kV 16 2/3 Hz AC from the

cetenary, and they convert it to 3 -phase AC for traction motors (3 phase
induction), and they also use regenerative breaking.There's also the french
TGV (Tren de Grand Vitesse) and the just new by Alstom (www.alstom.com) AGV
(Autometrisse de Grand Vitesse). Classic E-Loks have regular breaking, and
AC motors with series excitation, designed to work at 16 2/3 Hz. (Just like
the ones you'll find in a drill, but much larger, at 1 MW or more). They are
called universal motors, in the small scale, because they can work both in
AC and DC. I'm wondering, how large their brushes are... In the 300 MW turbo
generator, the brushes that suplly the excitation current, are as large as
bricks. Newer type of turbo generators are brushless. The speed record for a
classic E-Lok is held by Siemens' Taurus, IIRC 180 km/h with 12,000 HP.

Nice thing about the newer solid-state control systems (AC-Generator/
DC-Traction) is the ability to control wheel-slip. In the old days it
took a skilled engineer (the train-driving kind) to get maximum power
without slipping a lot (and wasting a lot of sand). Now modern units have
speed sensors on each individual wheel set and control the power flow to
individual traction motors. As soon as a wheel set starts to slip it can
redirect power flow to other traction motors to prevent the slipping set
from 'polishing the rail'. This prolongs life of the wheels and rail and
actually improves the maximum tractive effort a locomotive can deliver.
And when hauling 100+ cars of coal in a unit train up grade, tractive
effort is what keeps you moving.

I have no idea about train driving, but in Germany I got a local train from

a small city to Mannheim, and the Lokfuehrer (train driver) was driving it
like a race car... He accelerated fully to 130 km/h, and when he was close
to the next stop, he braked fully, too. It had one E-Lok, and two cars.
Also, the ICE starts like a race car. It's longer than 500 m, 12 cars, and I
think it accelerates to 100 km/h in 10 seconds.

You forgot to mention that traction motors often have separately powered
blower motors for air-cooling. This is because the motor may spend hours
operating at low speeds and shaft-mounted cooling fans are not enough.
The motor blower is usually mounted up inside the engine house and
connects to the traction motor via a large flexible duct.

Yeah, right, and the transformer is cooled by active oil cooling (that means

that the oil cools the trasformer, and there's a separate oil cooler. Like
the intercooler used in the tanks where I served at army, but that's a
differrent story).

Some diesel-electric unitl have six axles and six traction motors. The
trade-off is between how much power you can get to the traction motors and
how much weight you can keep on the wheels to keep them from slipping.
Sand is okay for starting and some special situations, but you can't carry
enough to use it for an entire run. But of course too much weight and you
need more axles to protect the rail from damage (depending on the size of
the rail being used).

But isn't a locomotive by itself heavy enough? Like 120 tons and above, with

fuel and all?
(Check at www.wartsila.com some large diesels). In our new power station,
they have installed two 50 MW, 70,000 HP two-stroke diesels. To see how
2-stroke diesels work, look in www.howstuffworks.com.. The ships that travel
from Iraklion to Piraeus (the harbour of Athens) the new ones, have 4
Wartsila 12 V 46 4-stroke diesels. 12 is number of cylinders, in V, and with
a diameter of piston, 46 cm. When they travel normally at night, they fire
up 2 engines. But, when they make a day trip, they fire up all 4 engines at
full throttle, and the whole ship vibrates. A ship is the only place you can
get free electricity. In my last trip, I saw young students plugging their
laptops to the ship's receptacles. A free lunch, after all

daestrom
P.S. As you can see, I've seen a few railroad locomotives as well.
Mostly just the older EMD's though, not GE's newer 'green' units.
I have no idea what they are doing in continental Greece, they *should* have

electrified all routes.



--
Tzortzakakis Dimitrios
major in electrical engineering
mechanized infantry reservist
hordad AT otenet DOT gr
NB:I killfile googlegroups.
>

 

[Tzortzakakis Dimitrios]

? "daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> ?????? ??? ??????
news:4829fd51$0$30162$4c368faf@roadrunner.com...

"Tzortzakakis Dimitrios" <noone@nospam.void> wrote in message
news:g0c3sa$902$1@mouse.otenet.gr...

? "daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> ?????? ??? ??????
news:4828b130$0$7047$4c368faf@roadrunner.com...

"Michael Moroney" <moroney@world.std.spaamtrap.com> wrote in message
news:g0a1o5$bcq$1@pcls6.std.com...
"daestrom" <daestrom@NO_SPAM_HEREtwcny.rr.com> writes:


P.S. In the US, a 'tap-changer' may be built for either for unloaded
or
loaded operation. The 'unloaded' type can not be stepped to another
tap
while there is load on the unit (although it can still be energized).
It's
switch contacts cannot interrupt load though, so if you try to move it
while
loaded, you can burn up the tap-changer. The classic
'load-tap-changer' is
actually several switches that are controlled in a precise sequence to
shift
the load from one tap of the transformer to another while not
interrupting
the load current.

P.P.S. Load tap changers typically have a significant time-delay built
into
the controls so they do not 'hunt' or respond to short drops in voltage
such
as starting a large load. 15 seconds to several minutes is typical.
So
even with load-tap-changers, starting a single load that is a high
percentage of the system capacity will *still* result in a voltage dip.

Are the load tap generators configured make-before-break?
Break-before-make would mean a (very short) power outage every
activation
but make-before-break would mean a momentarily short-circuited winding
and
the break would involve interrupting a large short circuit current.

Certainly modern ones likely use thyristors and zero crossing
detectors.


I figured someone would 'bite'

Typical large power load-tap-changers have a primary winding and two
secondaries.
You mean a secondary and a tetriary? The transformer for the hotel load
of a 300 MW unit is powered directly from the turbo alternator (21 kV)
and has a secondary of 6.6 kV and a tetriary of again 6.6 kV. This is
done because it has wye-wye-wye connection (IIRC). The hotel load of such
a unit is 10%, also 30 MW, including 7 brown coal mills. Typical size of
a 6.6 kV motor is 1 MW.
One secondary produces about 100% of 'rated' secondary voltage. The
second secondary produces about 15% to 20% of the rated voltage, but has
numerous taps from end to end, about 2.5% 'steps'. (for a total of about
eight taps). The cental tap of the boost/buck winding is tied to one end
of the main secondary. The boost/buck can be used to step from 90% to
110% of the 'design' output. I suppose some can step over a wider range,
but I haven't run across them.

*TWO* rotary switches have each tap tied to one of the positions of each
rotory switch, and each 'wiper' is tied to single heavier contacts that
are opened in the operating sequence. The output side of these two
interrupting contacts are tied to each end of a large center-tapped
inductor.

So, normally both rotary switches are aligned to the same transformer
tap, both interrupting contacts are shut, and load current flows from
the boost/buck winding tap, splits and flows through both rotary
switches, both interrupting contacts, enters both ends of the inductor
and out the inductor center tap. Because the current flows into both
ends of the inductor and the mutual inductance of the two parts cancel,
there is little voltage drop in the inductor.

Begin step sequence:
1) Open one interrupting contactor. Now load current doubles through
half the inductor and is zero in the other half, so the voltage drop
across the inductor actually makes output voltage drop, even if trying
to step 'up'.
2) Move associated rotary switch to next step of transformer bank.
3) Close interrupting contactor. Now, the two rotary switches are
across different taps. The inductor prevents a excessive current,
otherwise you have a direct short of the two winding taps. Some tap
changers can stop at this point and are called 'half-step' units.
Obviously, the inductor has to be rated for sustained operation across a
step of the boost/buck winding plus load current in order to survive
sustained 'half step' operation.
4) But for tap changers that can't operate 'half-step', the sequence
continues. And opens the other interrupting contactor. Now the other
half of the inductor has full load current.
5) Move second rotary switch to next step (now both switches are on the
new step)
6) Close the second interrupting contactor. You're back in the initial
configuration, but with both rotary switches on a new transformer tap.
Quite the same principle is done with diesel locomotives and is called
diesel-electric transmission, and also in pure electric locomotives
(E-Lok in german, for Elektrische Lokomotive). The diesel engine,
2-stroke and usually 600 to 900 rpm at full throttle, is coupled to a
generator. The generator has small windings, connected in series for the
last notch, higher voltage and relatively smaller current, and in
parallel for start, higher amperage and smaller voltage. The traction
motors are directly coupled on the wheel shaft, and are air cooled. An
E-Lok has a trasformer, with the primary directly supplied by the
cetenary, 15 kV 16 2/3 Hz in Germany, and 25 kV 50 Hz in Greece, The
secondary uses the same principle. The typical size of a traction motor
is 1 MW, 4 (one each shaft) and maximum voltage 700 volts, and are series
wound motors with special construction to operate at 16 2/3 Hz (or 50 Hz
with today's technology). Typical power of a diesel locomotive is 2850
HP, while an electric is 6000 HP. with 1500 HP at each shaft, also ~1MW.
There is a heavy duty 12,000 HP diesel engine in USA(with 6 shafts, also
2000 HP at each shaft). The high speed ICE train (InterCityExpress) in
germany is 13,000 HP, has a normal travelling speed of 200 km/h, 2
locomotives, 3-phase induction motors, electronic drive.

In US, diesel-electric used to always be DC machines, but modern ones are
now AC generators with thyristers to regulate the power flow to the
traction motors. Traction motors are still DC however to allow for their
use in dynamic braking.

I suppose in Europe the better way to go would be regenerative braking,
putting the braking power back into the overhead line, but that would need
a static inverter. Probably the transformer secondary has a four-quadrant
converter to allow reversal of power flow ??

This is for sure in ICE, where they get 15 kV 16 2/3 Hz AC from the

cetenary, and they convert it to 3 -phase AC for traction motors (3 phase
induction), and they also use regenerative breaking.There's also the french
TGV (Tren de Grand Vitesse) and the just new by Alstom (www.alstom.com) AGV
(Autometrisse de Grand Vitesse). Classic E-Loks have regular breaking, and
AC motors with series excitation, designed to work at 16 2/3 Hz. (Just like
the ones you'll find in a drill, but much larger, at 1 MW or more). They are
called universal motors, in the small scale, because they can work both in
AC and DC. I'm wondering, how large their brushes are... In the 300 MW turbo
generator, the brushes that suplly the excitation current, are as large as
bricks. Newer type of turbo generators are brushless. The speed record for a
classic E-Lok is held by Siemens' Taurus, IIRC 180 km/h with 12,000 HP.

Nice thing about the newer solid-state control systems (AC-Generator/
DC-Traction) is the ability to control wheel-slip. In the old days it
took a skilled engineer (the train-driving kind) to get maximum power
without slipping a lot (and wasting a lot of sand). Now modern units have
speed sensors on each individual wheel set and control the power flow to
individual traction motors. As soon as a wheel set starts to slip it can
redirect power flow to other traction motors to prevent the slipping set
from 'polishing the rail'. This prolongs life of the wheels and rail and
actually improves the maximum tractive effort a locomotive can deliver.
And when hauling 100+ cars of coal in a unit train up grade, tractive
effort is what keeps you moving.

I have no idea about train driving, but in Germany I got a local train from

a small city to Mannheim, and the Lokfuehrer (train driver) was driving it
like a race car... He accelerated fully to 130 km/h, and when he was close
to the next stop, he braked fully, too. It had one E-Lok, and two cars.
Also, the ICE starts like a race car. It's longer than 500 m, 12 cars, and I
think it accelerates to 100 km/h in 10 seconds.

You forgot to mention that traction motors often have separately powered
blower motors for air-cooling. This is because the motor may spend hours
operating at low speeds and shaft-mounted cooling fans are not enough.
The motor blower is usually mounted up inside the engine house and
connects to the traction motor via a large flexible duct.

Yeah, right, and the transformer is cooled by active oil cooling (that means

that the oil cools the trasformer, and there's a separate oil cooler. Like
the intercooler used in the tanks where I served at army, but that's a
differrent story).

Some diesel-electric unitl have six axles and six traction motors. The
trade-off is between how much power you can get to the traction motors and
how much weight you can keep on the wheels to keep them from slipping.
Sand is okay for starting and some special situations, but you can't carry
enough to use it for an entire run. But of course too much weight and you
need more axles to protect the rail from damage (depending on the size of
the rail being used).

But isn't a locomotive by itself heavy enough? Like 120 tons and above, with

fuel and all?
(Check at www.wartsila.com some large diesels). In our new power station,
they have installed two 50 MW, 70,000 HP two-stroke diesels. To see how
2-stroke diesels work, look in www.howstuffworks.com.. The ships that travel
from Iraklion to Piraeus (the harbour of Athens) the new ones, have 4
Wartsila 12 V 46 4-stroke diesels. 12 is number of cylinders, in V, and with
a diameter of piston, 46 cm. When they travel normally at night, they fire
up 2 engines. But, when they make a day trip, they fire up all 4 engines at
full throttle, and the whole ship vibrates. A ship is the only place you can
get free electricity. In my last trip, I saw young students plugging their
laptops to the ship's receptacles. A free lunch, after all

daestrom
P.S. As you can see, I've seen a few railroad locomotives as well.
Mostly just the older EMD's though, not GE's newer 'green' units.
I have no idea what they are doing in continental Greece, they *should* have

electrified all routes.



--
Tzortzakakis Dimitrios
major in electrical engineering
mechanized infantry reservist
hordad AT otenet DOT gr
NB:I killfile googlegroups.
>

 

[Bob Shuman]

Batteries Plus with many retail locations sell them for a fair price as
well.

Bob

"James Sweet" <jamessweet1@trashmail.net> wrote in message
news:fLtWj.1516$i51.747@trndny09...

Brian wrote:
Michael Kennedy wrote:

Note: Some SmartUPS units require 24 volts.. i.e. 2 12v batteries in
series to run.

Yes, this unit has two 12V batteries. New ones are on order! Shipping
is more than the batteries themselves ... they are heavy.

-Brian


Did you check locally? Many places carry a selection, Frys had a whole
shelf of them, I don't recall what the prices were like though.