Toshiba TV29C90 problem; Image fades to black...

"d6xkr via ElectronicsKB.com" <u45258@uwe> wrote in message
news:883aeb25e685c@uwe...
Arfa Daily wrote:
hi

[quoted text clipped - 43 lines]

thanx

Seems to me that the advice being given on that forum, whilst not
definitive, is never-the-less exactly right. I would suggest that the
first
thing to do would be to check the pincushion amp, and its drive. Also, if
any caps *have* leaked (and you are not confusing the glue that's often
found around their bases, with leaked electrolyte), then they need to be
replaced. Just because they had enough go in them to just about do their
job
three days ago, doesn't mean that one of them hasn't gasped its last
today.

To use a car analogy, you can drive around today with half a millimetre of
lining material on your brake pads, that stop the car today, and squeal
metal on metal tomorrow ...

The 24C08 is an EEPROM, where all of the setup parameters are stored. It's
not at all unusual for these to get corrupted in TV sets, and to produce
symptoms like you describe, which are not correctable. However, it's often
necessary to pre-program a new blank one with a basic set of parameters,
before it will work.

Finally, a warning. If you are not used to working on monitors, take
extreme
care, as they employ switchmode power supplies, which are (literally)
potentially lethal. Also the high voltage generation circuits for the CRT
can give you a nasty bite, as can the CRT itself, long after you have
switched off.

Arfa



hi and thanx for your reply.....

i'm sorry my post didn't show the fourth chip which is;

4. KA3842B and also there was a fifth one......
E009C

i wrote it's data on the back of the paper containing all the data of the
chips i found, it's data are;

5. PM02AF
LM this one i couldn't get any datasheet about
358N

the fourth chip is smps controller, this makes me know only three out of
five
chips and i don't know exactly which is the pincushion amp, or where is
it's
drive. it's kind of making me handicaped not having the service manual for
this piece of hardware. also i don't have the proper test equips, only an
avo
meter, the data sheets and my personal experience.

today i replace the caps that i suspected of having leaked, and the truth
to
be said, the pincushion became less by 8mm which is small but positive
result.
also i tried to replace the ATMEL 24C08 EEPROM with a new blank one, but i
got a white screen with horizontal bright lines across it, it looked like
a
writing paper and i didn't see any thing but shadows of what really was to
be
shown behind this new look so i turned back to the old one and every thing
is
fine relatively.

the first chip i mentioned "no. 1" is a big ic and since the begining i
suspected it but i don't have it's data sheet as to decide whether or not
to
replace it. also it's said to be discontinued which makes me unsure
whether
will i find it on the market or not.

as a matter of fact the monitor is eight years old and all of it's
capacitors
are probably if not surely much older, so it needs all of it's caps to be
replaced. but i need to have it working as not to be throwing mony away
for
nothing.

you are right about being extra careful while working with this type of
hardware, but the smps isn't what i fear. what really makes me sweat my
juices out is the tube itself, when i'm working on it while online i know
that there is a 25+ kv infront of me. one mistake and i might be history
and
so i take emergency precautions while working with it. also i have proper
grounding which calms me down a little.

this is all i've got,

hope for the best solution.


thanx all

--
Click to expand...
Looking at www.eserviceinfo.com there are a lot of entries for Viewsonic
manuals. I only had a quick skim through, but there seemed to be lots of
listings for the e655 model which might be sufficiently similar to work by
??

The pincushion amp is likely to be discrete rather than a chip, and might be
based around FET on a small heatsink. Geometry correction waveforms are
often fed to it from that 'big' chip. I fear that you will not get too far
on this fault without a 'scope to look at the waveforms. I would absolutely
recommend against employing any kind of 'shotgun' approach at component
replacement, as you are likely to end up with more problems than you started
with.

As for the safety angle, I think you might be misunderstanding the relative
dangers of the HV generator circuitry, and the power supply. Whilst it is
true that the CRT's final anode will have around 25 kv on it, the source
impedance for this supply is relatively high. This means that the available
current at that voltage is quite limited. For sure, if you had a weak heart,
or managed to hang yourself right across that supply, receiving a shock from
it *might*, at a pinch, prove fatal. The much more likely outcome is a
stinging hand - probably with a cut across it where your hand collided with
the chassis during its rapid exit :) - some words that are completely
new to your children :) and wounded pride.

On the other hand, the switch mode power supply has around 380v dc on its
front end, and this is derived DIRECTLY from the incoming line voltage by a
bridge rectifier, so a relatively low impedance source with the current
limited *only* by the front end fuse, which is likely to be a 3 or 4 amp
ceramic type. This is enough to kill you. No joke. Fact.

So please take care around that area. Use an isolation transformer if you
have one. Makes life a little bit safer.

Arfa
 
<no@spam.please> wrote in message
news:48996d59$0$40316$4fafbaef@reader5.news.tin.it...
Arfa Daily ha scritto:
no@spam.please> wrote in message
news:48987cad$0$18150$4fafbaef@reader3.news.tin.it...

The problem is: when I put the disk (both original or cdr), the drawer
closes, the clamp loads the cd, the laser moves towards the center of
the disk and the disk starts spinning. After 4-5 sec, the disk stops and
the laser goes back to the home position (out of the disk area).

I don't know if it is a focus or track problem, or is a laser fault...

Those symptoms are pretty typical of a worn laser. Looking at the eye
pattern may help with diagnosis. If you can find a marked test point for
it, most manufacturers have the level there pretty much 'standardised' at
about 1v p-p.

Arfa

Thanks Arfa, I'll bring the player @work and scope it. I don't know how
the TP1 test point pinout, but found the RFO pin on the Sony ICX1367
This transport uses Sony KSS-240a laser pickup. I've read on the net that
Sony made 3 different versions of it and that not all fit the VRDS-7. Do
you know how to avoid buying the wrong spare part?
Regards,
Tony
Click to expand...
The KSS-240A is readily available - I get them from East Coast Transistor
Parts. 1-800-645-3516. They run about 35.00 plus freight. They're a little
more expensive because the 240 includes the RF amp, laser power, tracking
adjustments, RF balance etc all together as part of the pickup assembly,
unlike cheaper pickups like the KSS-213.

Mark Z.

Mark Z.
 
"sck0006" <skamego@gmail.com> wrote in message
news:d64384ed-43cc-48d3-a9f4-a7b3a0826609@k37g2000hsf.googlegroups.com...
I have a Kenwood VR-407 that keeps going into protection (turns off >&
power light blinks). The owner stated that it was a sudden
occurrence, no lightning strikes, shorted wires, etc... This unit uses
two amplifier modules, one STK413-020A for front & center >channels, and a
STK412-020A for the surrounds. I removed both >odules, the >unit powered
up no protection. I put in the front module, >he unit powered up no
protection. I removed the front & put in the >ear, the unit went into
protection. I assumed the rear module was >lown, purchased he new one for
~$30.00, put it in, & the unit still >oes into rotection. I don't have the
service manual on this unit, but >rom hat I can tell, each module uses the
same four power supplies. It
looks like there's a ą65V & a ą35V. Both supplies come up w/ no
ripple before the unit goes into protection. I wasn't able to get any
sort of quantitative measurements from the output terminals (at the
amplifier outputs, of course the rear panel terminals are cut off
because of the speaker relays), but I can safely say that none of the
output terminals are shorted to any supply or ground. I checked all
thru hole semi's for a nominal pn drop, nothing shorted out there,
which brings up another point.

How does everyone check transistors/diodes in-circuit? I've heard
many times that just checking the pn junction voltage isn't enough,
and I'll admit I've had a few that had a proper voltage but were
actually bad, but for the most part shouldn't it suffice?

I'm sure this will probably open up a battle between greats, but I'd
love to hear from everyone's experiences on this matter.

Thanks,
Steve
Click to expand...

Look at the output of each of the rear channels with a scope at the moment
the protection circuit "should" unlock and let the unit play. Maybe a large
DC spike at that moment. If so, you may well have a bad muting transistor.
Used to be a fairly common problem on many brands, though I haven't seen one
just lately...

Muting transistors are somewhat special and subs generally won't work. They
are specially doped so that the large negative bias applied to turn them off
won't damage the base-emitter junction. Sometimes digital transistors are
used for the purpose.

It is possible to defeat the power relay on many models, and bring the unit
up on a variac. This will usually allow you to check internal voltages,
regulated supplies, offsets, etc without regard to protection status.

If the unit has 2 switched outlets, this is easy. Bring the unit's own power
cord to one of it's own switched outlets, and use a double-ended POLARIZED
cord to connect the other switched outlet to your variac (if you have
one...) or a switched outlet strip. Make sure the polarity of the AC cord
has not been compromised or defeated - that hot and neutral don't get
reversed in the process, or there will be major sparks!

You're going to need a service manual if you don't already have one...

Mark Z.
 
<no@spam.please> wrote in message
news:48998585$0$18148$4fafbaef@reader3.news.tin.it...
Mark D. Zacharias ha scritto:
no@spam.please> wrote in message
news:48996d59$0$40316$4fafbaef@reader5.news.tin.it...

The KSS-240A is readily available - I get them from East Coast Transistor
Parts. 1-800-645-3516. They run about 35.00 plus freight. They're a
little more expensive because the 240 includes the RF amp, laser power,
tracking adjustments, RF balance etc all together as part of the pickup
assembly, unlike cheaper pickups like the KSS-213.

Mark Z.

Thank you Mark! Do you know anything more about the 3 different Sony
versions of the KSS-240A and how to recognize the correct one?
I found it on some german/uk spare part sellers too (I live in Italy and
shipping is likely faster), even at lower prices, but I'm wary of them.

Tony
Click to expand...
I've never seen any of the usual parts suppliers quoting anything other than
a 'standard' KSS240A. I've certainly never ordered them as anything
different for any of the many I have fitted. As Mark says, the RF amp and
adjustments are mounted on the laser itself which makes it a bit more
expensive, but note that these pots are factory set, and are NOT intended to
be adjusted. The laser should be fundamentally 'drop in and go'. The '240
doesn't even have a laser shorting point for transport. FWIW, the '240 was
never one of the most reliable lasers. I have also seen them as "NKS240A"
much cheaper, and as 'second source' cheaper than a genuine Sony type.
Personally, with this particular laser, by experience I would recommend that
you only buy a genuine Sony manufactured part. It says so on the box, and I
guess you would be able to check with the supplier before parting with your
cash.

Arfa
 
In article <l5uj94lr5i92i99t5j9stg90r5qrkoce7p@4ax.com>, Robin Taylor <robin@paradiseplace.org.uk> wrote:
Hi

Recently I brought an old Toyota, and needed a CD player, cheap...
eBay provide a CD with its separate master radio/casstte unit, the CD
was sold as not reading discs. Toyota compact Disc deck 34203

Firstly, thanks for the great CD FAQ:
http://www.repairfaq.org/sam/cdfaq.htm

This page was also invaluable for wiring up the radio/cassette unit to
my bench PSU and a couple of old 4 OHM PC speakers.
http://www.carstereohelp.net/wireharness_Toyota3.htm

I tested the unit, it loaded a disc but the display showed no track or
disc info. the player spun up the disc, tried to focus a few times
then ejected the disc and shut down.

So I opened it up, I cleaned the optics, feed in roller etc;
reassmbled the top of the player and tried again, no change.

I removed the main PCB from the underside, it looked clean. I tested a
few components around where the feed from the laser pickup came in,
all ok. I reattached it and 'scoped it but couldn't see much happening
and wasn't sure what should be where.

I was begining to think the laser pickup assembly may be defective.

Then on the main PCB, I noticed a 100uF 10v 85 degree Electroyltic
capacitor,( its body was dark teal and it was made by ELNA), situated
in front of where the Flexible flat cable from the laser pickup
connected to the PCB.
It appeared to be slightly buldging underneth.
I unsoldered it and a leg fell out of it!
Where it had been there was nasty black electrolyte! I cleaned up the
PCB with 91% isopropyl alcohol on a cotton bud/Q-tip.
As I am not working in electronics for a living anymore I didn't have
a new replacement capacitor. An old Compaq motherboard kindly doanated
a 100uF 16v 105 degree capacitor which was taller than the original.
I mount it at an angle, facing the connector, to avoid it hitting the
mechanism, on reassembly, (Note: a circle around the positive pin hole
denotes polarity on this PCB). I reassembled the unit inserted a CD,
it recognized it straight away and played it all without a problem! :)

Hope this helps someone in the future.

Best regards,

Robin
Click to expand...

I love hearing success stories like this!!!!!!! Way to go Robin!!!!!!!!!!!!
 
ajuniper@freeuk.com wrote:

I have annotated the diagram with the measured voltages (in red) and
indicated the components I have pulled and checked; the diagram can be
found at http://www.ajuniper.f2s.com/psu.jpg (2MB image).
Click to expand...
Could it be Q003? It should not be possible to have 1.2V at its base when
the emitter is grounded, if it works.

--
Ulrik Smed
Aarhus, Denmark
 
"Tony Ramone" <ramone.tony@gmail.com> wrote in message
news:e9afd15e-1fe5-4ddd-8f50-03e53c810d84@79g2000hsk.googlegroups.com...
Hi all, I've searched around this group a bit so I think I've and idea
where my problem may lie, but I thought I should ask anyway, just to
make sure.
The TV in question is a Beko 284222WNS. At a recent party in my house,
it was knocked off its table and landed on its screen. The weight of
it ripped the plug out of the wall socket (and broke off the "Earth"
pin, which was actually just a piece of plastic moulded to the plug).
Amazingly it didn't shatter, and from a brief look inside, nothing
seems to be broken or dislodged (it's a wee bit too heavy to pick it
up and shake it to see if anything rattles).
When I powered it up, the picture was gone completely, but the sound
seems to be OK. I can't feel any static from the screen on power-up so
I guess I've got no high voltage. Does this mean a transformer is
busted or could it be something else?
Any advice would be very helpful, I'm just wondering really if it's
worth my while taking it in to be repaired...
Cheers,
Anthony
Click to expand...
When you dropped it you fucked it up. Duh.
 
"Robin Taylor" <robin@paradiseplace.org.uk> wrote in message
news:l5uj94lr5i92i99t5j9stg90r5qrkoce7p@4ax.com...
Hi

Recently I brought an old Toyota, and needed a CD player, cheap...
eBay provide a CD with its separate master radio/casstte unit, the CD
was sold as not reading discs. Toyota compact Disc deck 34203

Firstly, thanks for the great CD FAQ:
http://www.repairfaq.org/sam/cdfaq.htm

This page was also invaluable for wiring up the radio/cassette unit to
my bench PSU and a couple of old 4 OHM PC speakers.
http://www.carstereohelp.net/wireharness_Toyota3.htm

I tested the unit, it loaded a disc but the display showed no track or
disc info. the player spun up the disc, tried to focus a few times
then ejected the disc and shut down.

So I opened it up, I cleaned the optics, feed in roller etc;
reassmbled the top of the player and tried again, no change.

I removed the main PCB from the underside, it looked clean. I tested a
few components around where the feed from the laser pickup came in,
all ok. I reattached it and 'scoped it but couldn't see much happening
and wasn't sure what should be where.

I was begining to think the laser pickup assembly may be defective.

Then on the main PCB, I noticed a 100uF 10v 85 degree Electroyltic
capacitor,( its body was dark teal and it was made by ELNA), situated
in front of where the Flexible flat cable from the laser pickup
connected to the PCB.
It appeared to be slightly buldging underneth.
I unsoldered it and a leg fell out of it!
Where it had been there was nasty black electrolyte! I cleaned up the
PCB with 91% isopropyl alcohol on a cotton bud/Q-tip.
As I am not working in electronics for a living anymore I didn't have
a new replacement capacitor. An old Compaq motherboard kindly doanated
a 100uF 16v 105 degree capacitor which was taller than the original.
I mount it at an angle, facing the connector, to avoid it hitting the
mechanism, on reassembly, (Note: a circle around the positive pin hole
denotes polarity on this PCB). I reassembled the unit inserted a CD,
it recognized it straight away and played it all without a problem! :)

Hope this helps someone in the future.

Best regards,

Robin
Click to expand...
Well, good for you then. After all that work, you ended up with a stereo
that still sounds like shit.
 
Tony Ramone wrote:
On Aug 7, 11:41 am, "Stacey Chuffo" <phsd-
every...@promisesandiego.com> wrote:
"Tony Ramone" <ramone.t...@gmail.com> wrote in message

news:e9afd15e-1fe5-4ddd-8f50-03e53c810d84@79g2000hsk.googlegroups.com...



Hi all, I've searched around this group a bit so I think I've and
idea where my problem may lie, but I thought I should ask anyway,
just to make sure.
The TV in question is a Beko 284222WNS. At a recent party in my
house, it was knocked off its table and landed on its screen. The
weight of it ripped the plug out of the wall socket (and broke off
the "Earth" pin, which was actually just a piece of plastic moulded
to the plug). Amazingly it didn't shatter, and from a brief look
inside, nothing seems to be broken or dislodged (it's a wee bit too
heavy to pick it up and shake it to see if anything rattles).
When I powered it up, the picture was gone completely, but the sound
seems to be OK. I can't feel any static from the screen on power-up
so I guess I've got no high voltage. Does this mean a transformer is
busted or could it be something else?
Any advice would be very helpful, I'm just wondering really if it's
worth my while taking it in to be repaired...
Cheers,
Anthony

When you dropped it you fucked it up. Duh.

Wow, really? Damn, I never considered that...
Click to expand...
It's probably the circuit board that is broken around the high voltage
transformer. This is quite heavy and is usually only carried by the board
itself, so a chock can easily break the board. Look for cracks and broken
tracks and repair the tracks, if you are lucky it hasn't blown anything
else.

--
Ulrik Smed
Aarhus, Denmark
 
"Arfa Daily" <arfa.daily@ntlworld.com> wrote in message
news:rugmk.182873$x66.34024@newsfe25.ams2...
no@spam.please> wrote in message
news:48998585$0$18148$4fafbaef@reader3.news.tin.it...
Mark D. Zacharias ha scritto:
no@spam.please> wrote in message
news:48996d59$0$40316$4fafbaef@reader5.news.tin.it...

The KSS-240A is readily available - I get them from East Coast
Transistor Parts. 1-800-645-3516. They run about 35.00 plus freight.
They're a little more expensive because the 240 includes the RF amp,
laser power, tracking adjustments, RF balance etc all together as part
of the pickup assembly, unlike cheaper pickups like the KSS-213.

Mark Z.

Thank you Mark! Do you know anything more about the 3 different Sony
versions of the KSS-240A and how to recognize the correct one?
I found it on some german/uk spare part sellers too (I live in Italy and
shipping is likely faster), even at lower prices, but I'm wary of them.

Tony

I've never seen any of the usual parts suppliers quoting anything other
than a 'standard' KSS240A. I've certainly never ordered them as anything
different for any of the many I have fitted. As Mark says, the RF amp and
adjustments are mounted on the laser itself which makes it a bit more
expensive, but note that these pots are factory set, and are NOT intended
to be adjusted. The laser should be fundamentally 'drop in and go'. The
'240 doesn't even have a laser shorting point for transport. FWIW, the
'240 was never one of the most reliable lasers. I have also seen them as
"NKS240A" much cheaper, and as 'second source' cheaper than a genuine Sony
type. Personally, with this particular laser, by experience I would
recommend that you only buy a genuine Sony manufactured part. It says so
on the box, and I guess you would be able to check with the supplier
before parting with your cash.

Arfa
Click to expand...
What he said. Should be a pretty standard KSS-240A.

mz
 
Brasto <bram.stolk@gmail.com> wrote:

This machine 8 MM VCR Pioneer VE-D70 is still almost in brandnew
condition although it must be over 10 years old and has been sitting
on the NON-repairables shelf for a long time. It is a nice example of
the few 8 MM Video Recorders which were available on the market.
Click to expand...
Well, it's around 20+ years old, not 10.

That model is a re-badged Sony and you might have better luck figuring that
model out and looking for it instead of the Pioneer manual. At one time or
another I stumbled into a couple websites that had reviews of 8mm decks from
that era.

That particular machine was noted because it was one of the few that
supported the PCM recording format, audio only and would provide 24 hours at
LP mode on six tracks.

The downside to it (besides being tape, a dying breed) is it was prior to
the Hi8 format and isn't as useful as one thinks. #2 on this list is parts
were nearly unavailable for it in the early 90's when those deck first
started to fail. These days unless you get one for parts and make one out of
two, nothing in there can be ordered anymore.

The reason I mention that is your specific problem is likely on the power
board, or what resembles one. I might be confusing it with another chassis
but I beleive all roads to the transport end up at an STK device which was
an oddball. At the time (late 80's) there was a concept of splitting the
power supplies, one to feed the video/audio sections and another to do the
dirty work with the motors and transports.

So likely where you are measuring things at now are coming from a different
source than where the motors get fed from. I'd look towards the back of the
machine, the stk was mounted upside down, possibly using the rear as the
heat sink or it was on a heatsink and it was bolted to the chassis.

That deck is a challenge to work on because of the way it's built and I
agree, you probably aren't going to get anywhere without the manual.

Thinking about it, the Sony model was maybe ev-700 or ev-800.

But is from the mid/late 80's, that I'm sure about.

-bruce
bje@ripco.com
 
"Tony Ramone" <ramone.tony@gmail.com> wrote in message
news:e9afd15e-1fe5-4ddd-8f50-03e53c810d84@79g2000hsk.googlegroups.com...
Hi all, I've searched around this group a bit so I think I've and idea
where my problem may lie, but I thought I should ask anyway, just to
make sure.
The TV in question is a Beko 284222WNS. At a recent party in my house,
it was knocked off its table and landed on its screen. The weight of
it ripped the plug out of the wall socket (and broke off the "Earth"
pin, which was actually just a piece of plastic moulded to the plug).
Amazingly it didn't shatter, and from a brief look inside, nothing
seems to be broken or dislodged (it's a wee bit too heavy to pick it
up and shake it to see if anything rattles).
When I powered it up, the picture was gone completely, but the sound
seems to be OK. I can't feel any static from the screen on power-up so
I guess I've got no high voltage. Does this mean a transformer is
busted or could it be something else?
Any advice would be very helpful, I'm just wondering really if it's
worth my while taking it in to be repaired...
Cheers,
Anthony
Click to expand...
Maybe you need to read the F.A.Q. for the newsgroup before you post:

http://www.repairfaq.org/samnew/tvfaq/tvdropped.htm
 
"Ron(UK)" <ron@lunevalleyaudio.com> wrote in message
news:Zv2dnZ9on4jogAbVnZ2dnUVZ8vCdnZ2d@bt.com...
Hi chums

Does anyone have, or can point me to towards a circuit diagram (Schematic)
for an SWR Baby Blue bass amp.

At this point all I need to know is the value of the Master Volume pot.

Cheers
Ron(UK)

--
Lune Valley Audio
Public Address Systems
Hire Sales Maintenance
www.lunevalleyaudio.com
Click to expand...
There's some SWR schematics on here
http://www.schematicheaven.com/post70s.htm Ron, and also on here
http://www.freeinfosociety.com/electronics/schempage.php?cat=1 but they are
by model number rather than name. Might be similar if not the same.

Arfa
 
"d6xkr via ElectronicsKB.com" <u45258@uwe> wrote in message
news:885177717897a@uwe...
Robin Taylor wrote:
actually there is that diode just after the smps transformer but i don't
know
exactly if it is operational or not as it didn't grab my attention. i'll
check on it in the morning.

The Diodes after the the SMPSU are secondary rectifiers, they're most
probably ok.

You are looking for a big diode like this:
http://www.nxp.com/acrobat_download/datasheets/BY448_2.pdf
near the line output transistor, this is the transistor most likely
screwed to the aluminium box/heatsink surounding the line output
transformer. http://en.wikipedia.org/wiki/Flyback_transformer

I have seen this diode fail, in a few monitors, when it fails it
effects width and east/west correct,(pincusion).
All this said its been at least 10 years since I was fixing monitors.

Good luck,

Robin

i red this paper which gave me an idea about the larger picture of
horizontal
sync. http://www.repairfaq.org/sam/reppic/horiz-tv.pdf, and i think it
said
the same as you suggested, there is a problem with a peripheral component
around the flyback transformer. i also checked on the flyback trans. and
the
components around it, i found the damper diode and it checked right it's
operational, but it looks like a regular diode except for it's a little
bulky
and brownish in color. i found also another diode that looks like the one
the
datasheet you posted mentioned, it has a glass casing and it's oval in
shape
but it's very small and white and it's operational too.

the numbers of both the diodes are;

1. rg4a bulky one 2. 33ipn small one

finding that every thing is fine with these, i tried to check every
component
around the flyback transformer. every thing checked ok, nothing seemed
damaged, there were two more diodes and they were ok, there was a coil and
it
checked ok too. and a n-p-n BJT and it checked ok too. an elecrolytic
capacitor was there too and it was fine, but i'll recheck on it again may
be
replace it, i already got a new spare one.

not only this i checked on all the FETs on the pcb and they all were n-
channel type and they were fine. i have diode checker in my multi-meter
and
it shows the biasing voltage if the diode is operational. all of the solid
state devices i've checked were ok. all the BJTs around were ok too, and
the
diodes that were away from the flyback transformer were ok too. everything
just looks fine, no burnes, no exploding or leaking devices, or damaged
not
even a small resistor, which adds much to my confusion. does this have any
thing to do with damage to the flyback trans. itself?

hope any solution that fixes this situation appears in the horizon.

thanx

--
Message posted via ElectronicsKB.com
http://www.electronicskb.com/Uwe/Forums.aspx/repair/200808/1
Click to expand...
To be honest, I think that you have reached the point where you can't go
much further without a set of schematics and a 'scope. You need to see how
E-W raster correction modulation is achieved, and then to see why it's not
happening. It's usually not quite as straightforward on computer monitors,
as it is on a TV set. This is because the TV set runs at a constant line
rate, so only one condition needs to be corrected for, whereas a monitor has
to run at a number of different line and frame rates. As the line rate
changes, so does the tuning of the flyback transformer, and the deflection
yoke. This results in major width and geometry variations. To compensate for
all these conditions, the E-W correction often takes the form of a FET
modulator stage for the line output HT supply. This is driven from the sync
processor and timebase chip (often a big one at the front of the chassis)
which draws its correction data from the EEPROM. When you change the
parameters via the front panel user controls, these are stored back in the
EEPROM by the same chip. Brightness and contrast data are also stored in
here, as well as auto grey scale and beam current data, which is why the new
blank chip that you tried, didn't work.

I don't know what else to suggest that you do. Did you look on
eserviceinfo.com to see if the Viewsonic with almost the same model number
that's listed, was similar ?

This site claims to have the e653 manual for free, but they need you to sign
up for their newsletter

http://www.protech2u.com/download.html

Arfa
 
Ron(UK) <ron@lunevalleyaudio.com> wrote in message
news:Zv2dnZ9on4jogAbVnZ2dnUVZ8vCdnZ2d@bt.com...
Hi chums

Does anyone have, or can point me to towards a circuit diagram
(Schematic) for an SWR Baby Blue bass amp.

At this point all I need to know is the value of the Master Volume pot.

Cheers
Ron(UK)

--
Lune Valley Audio
Public Address Systems
Hire Sales Maintenance
www.lunevalleyaudio.com
Click to expand...
Assuming someone has totally removed it and lost it so nothing to measure, I
don't see what harm you can do by trying 10K,50K or 100K log or lin. Its not
as though you will put in a 50 ohm one. Then just optimisation.

SWR - anything to do with Simms Watts ?

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/
 
What about installing an antenna in the attic? Reception might be slightly
worse when it rains, but installation will be a heck of a lot simpler -- and
safer.

--- The Lady from Philadelphia
 
In article <63qhk76n.fsf@seas.upenn.edu>,
Samuel M. Goldwasser <sam@seas.upenn.edu> wrote:
dkcombs@panix.com (David Combs) writes:

In article <ljzk2sqx.fsf@seas.upenn.edu>,
Samuel M. Goldwasser <sam@seas.upenn.edu> wrote:
David Lesher <wb8foz@panix.com> writes:

sam@ece.drexel.edu writes:

So UPenn and Drexel have pulled the plug on their USENET news
servers. I'm looking for recommendations on newsgroup access,
preferably via GNUS, which many consider antiquated, as far as I can
tell, it is 10 times faster to read and post than using the fancy GUI
"modern" alternatives.


Get a Panix account <http://www.panix.com/shell.html

That's something to consider.

Thanks!

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/

And then use "trn4" as your newsreader.

What's wrong with emacs? :)
Click to expand...
I love emacs -- use it virtually every second I'm on the
computer (except when on the net, browsing; then it *must*
be lynx (line-mode).

Never tried it for newsgroups -- gnus?

This trn is *so* good and *so* fast, with nifty-keen wee
graph showing "you are here" among read and non-read posts,
man is it cool. Give it a try -- better, have someone show
it to you.


David
 
"Jack00" <SPal508596@aol.com> wrote in message
news:9033ca30-01f8-41c9-bb23-a16031092079@f63g2000hsf.googlegroups.com...
When I switch this television set on it works fine but after 10
minutes there is field collapse and the sound is ok. I heard it has
an Orion chassis. Does anyone know for which model? What normally
goes wrong here? Thanks
Click to expand...
By "field collapse" do you mean loss of vertical deflection (picture drops
to a single line across the screen from right to left) ?

Vertical problems were frequent on Toshiba chassis sets for a number of
years in the 90's and into the 2000's.


Mark Z.
 
"Jack00" <SPal508596@aol.com> wrote in message
news:9033ca30-01f8-41c9-bb23-a16031092079@f63g2000hsf.googlegroups.com...
When I switch this television set on it works fine but after 10
minutes there is field collapse and the sound is ok. I heard it has
an Orion chassis. Does anyone know for which model? What normally
goes wrong here? Thanks
Click to expand...
IT SOUNDS LIKE IT'S FUCKED UP.
 
"Mark D. Zacharias" <nonsense@nonsense.net> wrote in message
news:exenk.35346$ZE5.30898@nlpi061.nbdc.sbc.com...
"Jack00" <SPal508596@aol.com> wrote in message
news:9033ca30-01f8-41c9-bb23-a16031092079@f63g2000hsf.googlegroups.com...
When I switch this television set on it works fine but after 10
minutes there is field collapse and the sound is ok. I heard it has
an Orion chassis. Does anyone know for which model? What normally
goes wrong here? Thanks

By "field collapse" do you mean loss of vertical deflection (picture drops
to a single line across the screen from right to left) ?

Vertical problems were frequent on Toshiba chassis sets for a number of
years in the 90's and into the 2000's.


Mark Z.
Click to expand...
That's because those motherfuckers are made by Orion motherfuckin Electric
which makes fucked up motherfuckers.
 
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