Toshiba TV29C90 problem; Image fades to black...

Wiebe Cazemier <wiebe@halfgaar.net> wrote in
news:fcc4$48135a13$d4cc82be$10201@cache3.tilbu1.nb.home.nl:

On Saturday 26 April 2008 13:21, bz wrote:

Sounds like you might have an intermittent short to ground on a power
supply line, perhaps inside a bad capacitor.
Or an intermittent connection in the voltage sensing circuits, or the
AC line into the power supply.

The problem here is, that I'm not too familiar with CRT screen
electronics. I'm pretty well versed in audio electronics and other more
common, low voltage, stuff, but I've never really had to deal with CRTs,
so I don't know too much about them, or how to localize the circuits you
mentioned (except perhaps the PSU).

Would you happen to know of a good book/guide about CRT repair, or at
least an explanation of the insides?


Intermittents are difficult to localize and fix.

Tell me about it... This fault only happens when it's just turned on,
thus far, and very hard to reproduce.
So, what is different about 'just turned on'?
Components are cool.
High transient currents occur.

Look for places that those can make a difference.

Perhaps you can narrow down the problem by monitoring voltages at
various points while it is acting up.

I also have a transient recorder, although only a single channel. Still,
it should be useful. However, come to think of it, the voltages inside
the monitor are probably too high for it...
From the symptoms, I would start by looking at the PSU outputs.
Troubleshoot by 'divide and conquer'.

Divide the device logically into two halves, and localize the problem to
one of the two.

Continue until you reach the bad part.






--
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
 
Audiostatic is still in business.

http://www.audiostatic.com/contact.html
 
Audiostatic is still in business.

http://www.audiostatic.com/contact.html
 
"Deodiaus" <deodiaus@yahoo.com> wrote in message
news:2f85e038-fd1b-4f6c-aa9d-f5327d7a823f@x41g2000hsb.googlegroups.com...
which will cost a bundle to
fix
or repair.
While doing a search on the web, I found the same model (really cheap)
but
wired for 280V, instead of the 230 V load that my wiring is supplies.
Now, I was thinking of buying the cheap 280V model and installing it
instead. Aside from rotating at a different speed and
maybe some power inefficiencies, are there any other drawbacks of
using the 280V model
instead?
If it's the same model motor, you might be able to rewire it for your 230V
supply. Look at the nameplate or inside the wiring chamber to see if there is a
wiring diagram that details wiring connections for different voltages.
Barring that, you might search the Mfr's website (if they are still in business)
or Google for the make and model of your motor and see if there is any data on
it that details the wiring instructions.

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Some people are like Slinkies. Not really good for anything, but they bring a
smile to your face when pushed down the stairs.
 
<tx7123@yahoo.com> wrote in message
news:a60fee7d-739c-427d-bf6c-301464aa4ceb@k37g2000hsf.googlegroups.com...
OK I took the thing apart and sure enough, there was a sanyo 313E
mounted on a V shaped piece of metal(heatsink?). When I tapped
gently on the metal, everything now works fine.
The small board in question is AWR-011A, which according
to the schematic is the power supply unit.
I would think that if this was the roblem it would effect
everything, not just the radio.
Anyway I will run it for awhile with the case open,
and see if the problem recurs.


On Apr 26, 11:50 am, "Bob Shuman" <no_spam_...@sbcglobal.net> wrote:
Sounds like something is intermittent in the radio section (assumes
amplifier/auxiliary input/tape/etc. all are still working fine). I'd start
by looking for cold/broken solder connections under a magnifying. Or
alternatively, if that does not work and you can get at the board safely
while the unit is powered up, you can try pushing at various points with a
wooden dowel or similar non-conductive item. This may help you isolate the
area to take a closer look.

If these do not help, then you'll either need a schematic, a volt meter,
scope, and some troubleshooting skills to check the power supply voltages
at
key points and then follow the signal through the radio section or take it
to someone to do the work for you.

Bob

tx7...@yahoo.com> wrote in message

news:facbbdcd-1b25-4648-a91b-6c409b7924d8@56g2000hsm.googlegroups.com...



I have a pioneer sx-727 receiver, I'm the original owner (33 years).
Recently the radio stopped working.
Everything else works great.
FM, AM no difference does NOT work.
The tuning meter does not move as I turn the tuning dial.
If I turn the volume up, I can hear some static thru the speakers.
Occasionally the radio will spontaneously work for a while,
and then return to this dead mode.
All the other inputs cd, turntable work fine.
Any ideas what the problem might be?
Thanks.- Hide quoted text -

- Show quoted text -

Resolder the 313 regulator.

Mark Z.
 
<tx7123@yahoo.com> wrote in message
news:a60fee7d-739c-427d-bf6c-301464aa4ceb@k37g2000hsf.googlegroups.com...
OK I took the thing apart and sure enough, there was a sanyo 313E
mounted on a V shaped piece of metal(heatsink?). When I tapped
gently on the metal, everything now works fine.
The small board in question is AWR-011A, which according
to the schematic is the power supply unit.
I would think that if this was the roblem it would effect
everything, not just the radio.
Anyway I will run it for awhile with the case open,
and see if the problem recurs.


On Apr 26, 11:50 am, "Bob Shuman" <no_spam_...@sbcglobal.net> wrote:
Sounds like something is intermittent in the radio section (assumes
amplifier/auxiliary input/tape/etc. all are still working fine). I'd start
by looking for cold/broken solder connections under a magnifying. Or
alternatively, if that does not work and you can get at the board safely
while the unit is powered up, you can try pushing at various points with a
wooden dowel or similar non-conductive item. This may help you isolate the
area to take a closer look.

If these do not help, then you'll either need a schematic, a volt meter,
scope, and some troubleshooting skills to check the power supply voltages
at
key points and then follow the signal through the radio section or take it
to someone to do the work for you.

Bob

tx7...@yahoo.com> wrote in message

news:facbbdcd-1b25-4648-a91b-6c409b7924d8@56g2000hsm.googlegroups.com...



I have a pioneer sx-727 receiver, I'm the original owner (33 years).
Recently the radio stopped working.
Everything else works great.
FM, AM no difference does NOT work.
The tuning meter does not move as I turn the tuning dial.
If I turn the volume up, I can hear some static thru the speakers.
Occasionally the radio will spontaneously work for a while,
and then return to this dead mode.
All the other inputs cd, turntable work fine.
Any ideas what the problem might be?
Thanks.- Hide quoted text -

- Show quoted text -

Resolder the 313 regulator.

Mark Z.
 
In <F_OQj.1657$F13.1155@newsfe07.lga> Jamie <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> writes:

are you sure it isn't 208 ?

--http://webpages.charter.net/jamie_5"


I'd be suspicious that the 280V was a misreading somehow of 230V.
that sounds more plausible.
Or... of 208V. If you have a "three phase" circuit
coming into a building, and you run two "hot" wires
to your appliance (or motor), the effective voltage
you're getting is 208V.

There's enough overlap so that a standard 240V appliance
such as, say, a larger air conditioner, will work more
or less ok on 208V. And vice versa.

But there is most assuredely a difference in the
two circuits, so for optimal results, you'll want
an appliance (or motor) designed for the specific
wiring in your facility.

--
_____________________________________________________
Knowledge may be power, but communications is the key
dannyb@panix.com
[to foil spammers, my address has been double rot-13 encoded]
 
----------------------------
"jakdedert" <jakdedert@bellsouth.net> wrote in message
news:89RQj.52246$r76.50400@bignews8.bellsouth.net...
Jamie wrote:
hr(bob) hofmann@att.net wrote:

On Apr 26, 6:14 pm, Jamie
jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:

Deodiaus wrote:

I have a broken pool motor [magnetek y56y] which will cost a bundle to
fix
or repair.
While doing a search on the web, I found the same model (really cheap)
but
wired for 280V, instead of the 230 V load that my wiring is supplies.
Now, I was thinking of buying the cheap 280V model and installing it
instead. Aside from rotating at a different speed and
maybe some power inefficiencies, are there any other drawbacks of
using the 280V model
instead?

are you sure it isn't 208 ?

--http://webpages.charter.net/jamie_5"


I'd be suspicious that the 280V was a misreading somehow of 230V.
that sounds more plausible.

I'm a little confused about a 230 volt circuit. In what part of the world
does the utility supply 230v?

jak
-----
Depending on the age of the motor it could be rated 230V which now has crept
up to 240V just as once we had 110V, then 115V then 120V as nominal
voltages -(except for the radio people who settled on 117V and assumed that
that was what you got.).

--

Don Kelly dhky@shawcross.ca
remove the X to answer
 
"jakdedert" <jakdedert@bellsouth.net> wrote in message
news:89RQj.52246$r76.50400@bignews8.bellsouth.net...
Jamie wrote:
hr(bob) hofmann@att.net wrote:

On Apr 26, 6:14 pm, Jamie
jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:

Deodiaus wrote:

I have a broken pool motor [magnetek y56y] which will cost a bundle to
fix
or repair.
While doing a search on the web, I found the same model (really cheap)
but
wired for 280V, instead of the 230 V load that my wiring is supplies.
Now, I was thinking of buying the cheap 280V model and installing it
instead. Aside from rotating at a different speed and
maybe some power inefficiencies, are there any other drawbacks of
using the 280V model
instead?

are you sure it isn't 208 ?

--http://webpages.charter.net/jamie_5"


I'd be suspicious that the 280V was a misreading somehow of 230V.
that sounds more plausible.

I'm a little confused about a 230 volt circuit. In what part of the world
does the utility supply 230v?

jak
Most except the USA and Canada and a few others.

John G.
 
"jakdedert" <jakdedert@bellsouth.net> wrote in message
news:89RQj.52246$r76.50400@bignews8.bellsouth.net...
Jamie wrote:
hr(bob) hofmann@att.net wrote:

On Apr 26, 6:14 pm, Jamie
jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:

Deodiaus wrote:

I have a broken pool motor [magnetek y56y] which will cost a bundle to
fix
or repair.
While doing a search on the web, I found the same model (really cheap)
but
wired for 280V, instead of the 230 V load that my wiring is supplies.
Now, I was thinking of buying the cheap 280V model and installing it
instead. Aside from rotating at a different speed and
maybe some power inefficiencies, are there any other drawbacks of
using the 280V model
instead?

are you sure it isn't 208 ?

--http://webpages.charter.net/jamie_5"


I'd be suspicious that the 280V was a misreading somehow of 230V.
that sounds more plausible.

I'm a little confused about a 230 volt circuit. In what part of the world
does the utility supply 230v?

jak
Most except the USA and Canada and a few others.

John G.
 
In alt.engineering.electrical 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?

http://en.wikipedia.org/wiki/Mains_power_systems

There are two different flavors of 220/230/240 volts. Some places have a
simple system with one wire hot and one wire grounded. Other places have
a split system where the voltage is split in half to get 110/115/120 volts
relative to ground, by adding a additional "middle" conductor that is the
grounded one.

--
|WARNING: Due to extreme spam, I no longer see any articles originating from |
| Google Groups. If you want your postings to be seen by more readers |
| you will need to find a different place to post on Usenet. |
| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |
 
"DaveM" <masondg4499@comcast99.net> wrote in message
news:xPKdna3cPLk9CI7VnZ2dnUVZ_jadnZ2d@comcast.com...
"Deodiaus" <deodiaus@yahoo.com> wrote in message
news:2f85e038-fd1b-4f6c-aa9d-f5327d7a823f@x41g2000hsb.googlegroups.com...
I have a broken pool motor [magnetek y56y] which will cost a bundle to
fix
or repair.
While doing a search on the web, I found the same model (really cheap)
but
wired for 280V, instead of the 230 V load that my wiring is supplies.
Now, I was thinking of buying the cheap 280V model and installing it
instead. Aside from rotating at a different speed and
maybe some power inefficiencies, are there any other drawbacks of
using the 280V model
instead?

If it's the same model motor, you might be able to rewire it for your 230V
supply. Look at the nameplate or inside the wiring chamber to see if
there is a wiring diagram that details wiring connections for different
voltages.
Barring that, you might search the Mfr's website (if they are still in
business) or Google for the make and model of your motor and see if there
is any data on it that details the wiring instructions.

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters
in the address)

What's broken on the original motor? There isn't a whole lot to go wrong
with these, I've yet to run into one I couldn't fix.
 
"Jamie" <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in message
news:F_OQj.1657$F13.1155@newsfe07.lga...
hr(bob) hofmann@att.net wrote:

On Apr 26, 6:14 pm, Jamie
jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:

Deodiaus wrote:

I have a broken pool motor [magnetek y56y] which will cost a bundle to
fix
or repair.
While doing a search on the web, I found the same model (really cheap)
but
wired for 280V, instead of the 230 V load that my wiring is supplies.
Now, I was thinking of buying the cheap 280V model and installing it
instead. Aside from rotating at a different speed and
maybe some power inefficiencies, are there any other drawbacks of
using the 280V model
instead?

are you sure it isn't 208 ?

--http://webpages.charter.net/jamie_5"


I'd be suspicious that the 280V was a misreading somehow of 230V.
that sounds more plausible.

Misreading of 208V undoubtably, 208 is very common in commercial buildings,
that and 277.
 
"jakdedert" <jakdedert@bellsouth.net> wrote in message
news:89RQj.52246$r76.50400@bignews8.bellsouth.net...
Jamie wrote:
hr(bob) hofmann@att.net wrote:

On Apr 26, 6:14 pm, Jamie
jamie_ka1lpa_not_valid_after_ka1l...@charter.net> wrote:

Deodiaus wrote:

I have a broken pool motor [magnetek y56y] which will cost a bundle to
fix
or repair.
While doing a search on the web, I found the same model (really cheap)
but
wired for 280V, instead of the 230 V load that my wiring is supplies.
Now, I was thinking of buying the cheap 280V model and installing it
instead. Aside from rotating at a different speed and
maybe some power inefficiencies, are there any other drawbacks of
using the 280V model
instead?

are you sure it isn't 208 ?

--http://webpages.charter.net/jamie_5"


I'd be suspicious that the 280V was a misreading somehow of 230V.
that sounds more plausible.

I'm a little confused about a 230 volt circuit. In what part of the world
does the utility supply 230v?

jak
In theory, it's 230 on a single phase - neutral circuit here in the UK now,
but in practice, it's actually nearer the previously accepted 240v for the
most part ...

Arfa
 
Just in case anyone is tempted...

A legitimate organization soliciting user opinions would never charge the
user to sign up. These costs would be borne by the companies wanting the
opinions.
 
Just in case anyone is tempted...

A legitimate organization soliciting user opinions would never charge the
user to sign up. These costs would be borne by the companies wanting the
opinions.
 
Wiebe Cazemier <wiebe@halfgaar.net> wrote in
news:dba16$48146d43$d4cc82be$18933@cache6.tilbu1.nb.home.nl:

On Saturday 26 April 2008 19:40, bz wrote:

So, what is different about 'just turned on'?
Components are cool.
High transient currents occur.

Look for places that those can make a difference.

(snip)

From the symptoms, I would start by looking at the PSU outputs.
Troubleshoot by 'divide and conquer'.

Divide the device logically into two halves, and localize the problem
to one of the two.

Continue until you reach the bad part.

I've been reading the repair faq at
http://www.repairfaq.org/sam/crtfaq.htm. At some point it says this:

Occasionally, small conductive flakes or whiskers present since the day
of manufacture manage to make their way into a location where they short
out adjacent elements in the CRT electron guns. Symptoms may be
intermittent or only show up when the TV or monitor is cold or warm or
in-between. Some possible locations are listed below:

One of them is: Heater to cathode (H-K). The cathode for the affected
gun will be pulled to the heater (filament) bias voltage - most often 0
V (signal ground). In this case, one color will be full on with retrace
lines. Where the heater is biased at some other voltage, other symptoms
are possible like reduced brightness and/or contrast for that color.
This is probably the most common location for a short to occur.

That appears to be exactly what's happening. The blue gun is turned on
completely, also showing the retrace lines. Also, remember that I have
been able to reproduce the fault a couple of times by tapping the
cathode assembly.
If you are SURE that no vibrations from your tapping traveled elsewhere,
that is a strong clue.
Otherwise it can be a misleading clue.

I have played the 'taps' game and won. I have played it and lost.
It is best when you can make smaller and smaller taps while getting closer
and closer to the problem.

If the tap will only occasionally trigger/fix the problem, then it is easy
to be misled.

I will try the "put the monitor on it's face and try tapping it to
dislodge the short" method first. If it works, it would be a very low
tech, but effective solution :)

The "blow out the short with a capacitor" method also seems fun, but
also a little risky :)
When I had a TV repair shop, in the early 70's, we had a tester for picture
tubes.
It had a short indicator and a 'remove short' button that discharged a
capacitor through the short.
Sometimes it would fix things. Sometimes it would make things worse.

Good luck with your experiment. Hopefully, it won't drop something into the
center of the shadow mask.

Be aware that with 15 lb of air pressing on each square inch of the CRT,
you are playing with a live bomb.

I once took a picture tube out, laid it on its faceplate, got about 50 feet
away and tossed rocks at it.

Woomp. Dust and dirt and glass flew everywhere.

Chunks of the face plate (glass about 1 1/2 inches thick) landed about 50
feet BEHIND me.

Now, I would want a thick sheet of lexan between me and any CRT that I was
tapping upon, and safety goggles, gloves.




--
bz

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

bz+spr@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap
 
Wiebe Cazemier <wiebe@halfgaar.net> wrote in
news:dba16$48146d43$d4cc82be$18933@cache6.tilbu1.nb.home.nl:

On Saturday 26 April 2008 19:40, bz wrote:

So, what is different about 'just turned on'?
Components are cool.
High transient currents occur.

Look for places that those can make a difference.

(snip)

From the symptoms, I would start by looking at the PSU outputs.
Troubleshoot by 'divide and conquer'.

Divide the device logically into two halves, and localize the problem
to one of the two.

Continue until you reach the bad part.

I've been reading the repair faq at
http://www.repairfaq.org/sam/crtfaq.htm. At some point it says this:

Occasionally, small conductive flakes or whiskers present since the day
of manufacture manage to make their way into a location where they short
out adjacent elements in the CRT electron guns. Symptoms may be
intermittent or only show up when the TV or monitor is cold or warm or
in-between. Some possible locations are listed below:

One of them is: Heater to cathode (H-K). The cathode for the affected
gun will be pulled to the heater (filament) bias voltage - most often 0
V (signal ground). In this case, one color will be full on with retrace
lines. Where the heater is biased at some other voltage, other symptoms
are possible like reduced brightness and/or contrast for that color.
This is probably the most common location for a short to occur.

That appears to be exactly what's happening. The blue gun is turned on
completely, also showing the retrace lines. Also, remember that I have
been able to reproduce the fault a couple of times by tapping the
cathode assembly.
If you are SURE that no vibrations from your tapping traveled elsewhere,
that is a strong clue.
Otherwise it can be a misleading clue.

I have played the 'taps' game and won. I have played it and lost.
It is best when you can make smaller and smaller taps while getting closer
and closer to the problem.

If the tap will only occasionally trigger/fix the problem, then it is easy
to be misled.

I will try the "put the monitor on it's face and try tapping it to
dislodge the short" method first. If it works, it would be a very low
tech, but effective solution :)

The "blow out the short with a capacitor" method also seems fun, but
also a little risky :)
When I had a TV repair shop, in the early 70's, we had a tester for picture
tubes.
It had a short indicator and a 'remove short' button that discharged a
capacitor through the short.
Sometimes it would fix things. Sometimes it would make things worse.

Good luck with your experiment. Hopefully, it won't drop something into the
center of the shadow mask.

Be aware that with 15 lb of air pressing on each square inch of the CRT,
you are playing with a live bomb.

I once took a picture tube out, laid it on its faceplate, got about 50 feet
away and tossed rocks at it.

Woomp. Dust and dirt and glass flew everywhere.

Chunks of the face plate (glass about 1 1/2 inches thick) landed about 50
feet BEHIND me.

Now, I would want a thick sheet of lexan between me and any CRT that I was
tapping upon, and safety goggles, gloves.




--
bz

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

bz+spr@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap
 
"James Sweet" <jamessweet@hotmail.com> wrote in message
news:yFWQj.134$_v1.102@trndny06...
"DaveM" <masondg4499@comcast99.net> wrote in message
news:xPKdna3cPLk9CI7VnZ2dnUVZ_jadnZ2d@comcast.com...
"Deodiaus" <deodiaus@yahoo.com> wrote in message

news:2f85e038-fd1b-4f6c-aa9d-f5327d7a823f@x41g2000hsb.googlegroups.com...
I have a broken pool motor [magnetek y56y] which will cost a bundle to
fix
or repair.
While doing a search on the web, I found the same model (really cheap)
but
wired for 280V, instead of the 230 V load that my wiring is supplies.
Now, I was thinking of buying the cheap 280V model and installing it
instead. Aside from rotating at a different speed and
maybe some power inefficiencies, are there any other drawbacks of
using the 280V model
instead?

If it's the same model motor, you might be able to rewire it for your
230V
supply. Look at the nameplate or inside the wiring chamber to see if
there is a wiring diagram that details wiring connections for different
voltages.
Barring that, you might search the Mfr's website (if they are still in
business) or Google for the make and model of your motor and see if
there
is any data on it that details the wiring instructions.

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate
characters
in the address)



What's broken on the original motor? There isn't a whole lot to go wrong
with these, I've yet to run into one I couldn't fix.
Me too. Usually it's just been corrosion that can be cleaned off and/or
lack or lubrication.
 
In article <fv1at5128ml@news3.newsguy.com>, phil-news-nospam@ipal.net
wrote:

There are two different flavors of 220/230/240 volts. Some places have a
simple system with one wire hot and one wire grounded. Other places have
a split system where the voltage is split in half to get 110/115/120 volts
relative to ground, by adding a additional "middle" conductor that is the
grounded one.
Sonny, you need to LEARN the difference between Ground and Neutral......
before you spout any further BS.......
 

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