Toshiba TV29C90 problem; Image fades to black...

[David]

You are still looking at the same voltages driving the convergence ic's.
Those should be replaced regardless. The vertical ic is not a concern if
you are not worried about the chance of having to open the set up again and
replace it later. It is not like you will have to make another trip out to
fix the set a second time.

Sony models use almost identical internal electronic chassis designs for any
given run. I would have to check but since your set does fall at the same
vintage, 7 years or so, as the other Sony chassis that had the same
problems, I would be suspect of the vertical output ic. To be sure is the
signal board with the fuses and vertical output ic mounted vertically on the
right side of the set (when looking from the rear) with the convergence
board mounted towards the front of the set?

David

Mirek Chmiel <mirekc@yahoo.com> wrote in message
news:3fb82c40$0$9746$afc38c87@...

Thanks David.
Since you were dealing with different TV before (RPTV KP-41EXR96 ), does
the
rest of your advise apply to my model. At this time, I don't have a
schematic for this TV. So far I verified, that all low ohm resistors are
OK.
Should I replaced vertical ICs?

Mirek
"David" <dkuhajda@locl.net.spam> wrote in message
news:3fb85649@news.greennet.net...
One special note. When you remove the old convergence ic's, completely
remove the old heatsink compound and reapply an air tight thin coating
of
heatsink compound to the new ic's. Make sure they are firmly attached
to
the heatsinks.

Be very careful not to damage or overheat the circuit boards when
removing
the old parts. Sony boards tend to be easily damaged and lift the
circuit
traces.

David

Mirek Chmiel <mirekc@yahoo.com> wrote in message
news:3fb80cf5$0$9745$afc38c87@...
This TV is about 7 years old. About 2 years ago it had similar
problem.
At
that time, we had a local company fix it. On the bill, they stated
replacement of one transistor. Unfortunately, I don't have that info
anymore
to specify which one.
This time, I did google search on this problem and found much useful
info.
The purpose for this email is to further pinpoint the root cause of my
problem.
For a couple of weeks, while TV was warming up, I did notice short
picture
problems. For a fraction of a second the picture would be distorted.
Because
of a short duration, I couldn't tell exactly what the distortion was.
Yesterday my family told me, that there was a problem with TV. I
couldn't
immediately check it out so can't say, if this was instantaneous or
not.
When I finally looked at it, I saw a pincushion problem. Today I
replaced
F902 fuse and for a short while, everything is OK. After few seconds
(10-20)
the red color fails and, on the convergence screen, it moves off half
of
the
screen to the left. Blue is still pretty good. At this time, I can
smell
a
burning component and I turn the TV off. After checking for hot
components,
I did notice, that the top STK is hot.

At this time, I'll follow the advice from David Kuhajda from
2000/06/09
for
a Sony RPTV KP-41EXR96 :
If the fuse is blowing, even intermittently you need to Replace both
STK
convergence output ic's, check all the low ohm resistors in the
convergence
output circuit. Then check the vertical output ic and the 2 small
fusible
resistor to the vertical ic, typically when one of the convergence
ic's
starts
to go it opens up the fuse, which unbalances the voltage to the
vertical
ic,
if
it is not bad now, it will likely fail within the next month. I had 3
in
a
row
that got 2 convergence ic's and a fuse, only to have the vertical ic
fail
within
a month later, so we now replace the vertical ic whenever either the
+15v
or
-15v fuse opens up, order the ic by number from MCM or other generic
parts
distributor, as well as the stk outputs, Sony wants way too much for
these
high
volume parts, and they buy them from the other manufacture as well.
David

If anyone has any additional info/advice please let me know.

Thank you.

Mirek

 

[Michael A. Terrell]

AlKlecks wrote:

Hi,

I find it pretty hard to find a shop that actually understands what
one is asking for... I my case most of the shops I called up they did
not even know the amplification class of their transistors in stock
(not to mention the voltage selection I need, or anything about
matched pairs).
So my question is - does anyone know a good shop that has the above
transistors with a K or L amplification factor (hfe around 80-160) and
a Vceo selection of 180V (2 or Z) and is located / ships to the US?
If this seems hard to come by - I found the following (possible)
substitions that are probably equally hard to get (plus, I have no
data at all regarding these transistors):

news:sci.electronics.repair would be a better place to look for help.
Check out Sam's RepairFAQ for a list of vendors who sell repair parts
for newer equipment.

2SB536 -- 2SA1011, 2SB1085, 2SA814, 2SA1078, 2SB1414

Industry Number : 2SB536M
NTE Device Number: NTE292
T-PNP,SI-POWER OUTPUT/SW,TO-220

2SD381 -- 2SC2344, 2SD1592, 2SC1624, 2SD1138, 2SD1562

Industry Number : 2SD381
NTE Device Number: NTE291
T-NPN,SI-POWER OUTPUT/SW,TO-220

Are there more recent types available that could be used and are
easier to find?

http://www.nteinc.com/

Thanks,

AlKlecks.

--


Michael A. Terrell
Central Florida

 

[Brenda Ann]

"Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message
news:3FB850ED.12B119C5@earthlink.net...

news:sci.electronics.repair would be a better place to look for help.
Check out Sam's RepairFAQ for a list of vendors who sell repair parts
for newer equipment.



2SB536 -- 2SA1011, 2SB1085, 2SA814, 2SA1078, 2SB1414

Industry Number : 2SB536M
NTE Device Number: NTE292
T-PNP,SI-POWER OUTPUT/SW,TO-220

2SD381 -- 2SC2344, 2SD1592, 2SC1624, 2SD1138, 2SD1562

Industry Number : 2SD381
NTE Device Number: NTE291
T-NPN,SI-POWER OUTPUT/SW,TO-220

Are there more recent types available that could be used and are
easier to find?

http://www.nteinc.com/

And what's really great about NTE is that you can download a database with
all that info on it..

 

[Steve Cothran]

A good vendor I have used for Japanese parts in Consolidated
Electronics. I think their # is 800-543-3568 or ceitron.com. They have
been in biz since I was a kid repairing 8-tracks, and also sell NTE's.

 

[William Sommerwerck]

And what's really great about NTE is that you can download
a database with all that info on it..

If you live near a well-stocked Fry's, you'll find a rack with gazillions of NTE
parts on it. Nice.

 

[Bill Jeffrey]

William Sommerwerck wrote:

If you live near a well-stocked Fry's, you'll find a rack with gazillions of NTE
parts on it. Nice.

Is there such a thing as a well-stocked Fry's? There are two Fry's in

metro Phoenix, and I have spent hours, literally, staring at empty racks
and Temporarily Out of Stock tags.

Bill Jeffrey

--
Remove NOSPAM from my address before e-mailing a reply.
Outgoing mail is automatically scanned by Norton Anti-Virus.

 

[William Sommerwerck]

If you live near a well-stocked Fry's, you'll find a rack with
gazillions of NTE parts on it. Nice.

Is there such a thing as a well-stocked Fry's? There are two
Fry's in metro Phoenix, and I have spent hours, literally,
staring at empty racks and Temporarily Out of Stock tags.

Don't know. The one near me opened just two months ago, and it's stocked coming
out the keister.

Personally, I don't find staring at empty racks for extended periods to be very
entertaining. But, chacun a son gout.

 

[bobinphx]

Bill,
More than once I have complained to the parts area manager. Result, Same
old out of stock condition. My guess is that Ill have to talk to someone in
the upper end of sales and explain about how getting folks who like to fix
things in the store, sells other stuff also. A happy customer comes back. If
it wasn't for the very low sale prices they have (read rebates), I wouldn't
even go into that mess of a store. The check out line is the largest pile of
BS I've ever seen.

Bob in phx (who now feels better after venting)
p.s. I was spoiled by Tech America when they were here. Nice stock and good
guys behind the counter. I never found them out of stock on anything. To bad
the rest of the store sucked...

 

[bobinphx]

Bill,
You might try circuit specialist in Mesa. They are pretty well stocked, but
don't expect any low prices.

Bob in phx

 

[Brian]

Don't know. The one near me opened just two months ago, and it's stocked coming
out the keister.

After wandering through the Fry's that opened here in San Marcos last
June, what impressed me most was how many parts they carry that are
useful for repairing old radios. I found good-sounding 4-ohm speakers
(4", 5", 6"), 450-volt electrolytics, all kinds of film caps, power
resistors, 3AG fuses, RF inductors and toroids, 70.7-volt line
transformers (good for matching 500- or 5000-ohm boatanchors to 4- or
8-ohm speakers), bulbs (#44, #47, and dozens more), contact cleaner,
all kinds of soldering stuff, test equipment including Tektronix
scopes, and other things I've forgot. They even have some Philmore
parts--I don't recall seeing that name on a parts rack since the
1960s. It's been a long time since I've found this kind of stuff
stocked nearby.

Brian

 

[William Sommerwerck]

After wandering through the Fry's that opened here in San Marcos last
June, what impressed me most was how many parts they carry that are
useful for repairing old radios. I found good-sounding 4-ohm speakers
(4", 5", 6"), 450-volt electrolytics, all kinds of film caps, power
resistors, 3AG fuses, RF inductors and toroids, 70.7-volt line
transformers (good for matching 500- or 5000-ohm boatanchors to 4- or
8-ohm speakers), bulbs (#44, #47, and dozens more), contact cleaner,
all kinds of soldering stuff, test equipment including Tektronix
scopes, and other things I've forgot. They even have some Philmore
parts--I don't recall seeing that name on a parts rack since the
1960s. It's been a long time since I've found this kind of stuff
stocked nearby.

As I said to the Fry brothers on opening day... "No more Radio Shack."

 

[Bill Jeffrey]

bobinphx wrote:

Bill,
You might try circuit specialist in Mesa. They are pretty well stocked, but
don't expect any low prices.

Bob in phx


Thanks for the tip, Bob. I don't mind paying. I DO MIND driving 50

miles round trip, killing half a day, and finding only half of the parts
on my list - thus accomplishing exactly nothing toward my project.

Seems to me the Fry's in Silicon Valley weren't much better.

Bill

--
Remove NOSPAM from my address before e-mailing a reply.
Outgoing mail is automatically scanned by Norton Anti-Virus.

 

[Jeffrey D Angus]

Bill Jeffrey wrote:

Is there such a thing as a well-stocked Fry's? There are two Fry's in
metro Phoenix, and I have spent hours, literally, staring at empty racks
and Temporarily Out of Stock tags.

There aren't any down here either.
Thousand oaks, Coste Mesa, Burbank, Manhattan Beach....

All have either gaping holes in the stock, or what they do have, has
the dreaded "A Fry's Sales Associate has checked the contents." tag
of death.

Jeff


--
"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety." Benjamin Franklin
"A life lived in fear is a life half lived."
Tara Morice as Fran, from the movie "Strictly Ballroom"

 

[AlKlecks]

Thanks Steve,

they even had the power transistors I didn't dare to ask (2SA909,
2SC1486). So I ordered from them.

Just a remark, I do have the NTE software (
http://www.moyerelectronics.com/DownLoads/qc10setup.exe ) and was
finding the "matches" but the NTE types are not really the same.
As for Fry's, only if I'm really desperate and willing to pay extra I
go and check out whats available there... Standard stuff (R's, C's)
they are pretty well stocked here in Austin, but nothing exotic.

Thx,

AlKlecks.

fake@fake.com (Steve Cothran) wrote in message news:<3fb8b7c6.44274593@news.apid.com>...

A good vendor I have used for Japanese parts in Consolidated
Electronics. I think their # is 800-543-3568 or ceitron.com. They have
been in biz since I was a kid repairing 8-tracks, and also sell NTE's.

 

[Ol' Duffer]

Philips has been making a lot of enemies the last few years.
We had one customer who had to actually take them to court.
6 month old 32" set with bad flyback transformer. Transformer
not available. Okay then send me the whole board. Board not
available. We have kept the repair department open to serve
our past customers, but we no longer sell Philips sets.

 

[DaveC]

On Wed, 19 Nov 2003 12:11:30 -0800, Mike wrote
(in message <3fbbcd1e.7157864@News.xtra.co.nz&gt:

On Wed, 19 Nov 2003 19:42:06 GMT, Robert Baer
robertbaer@earthlink.net> wrote:

Looks like it could be a bridge rectifier; most power FETs in that
kind of a package have only three terminals per FET (and there are some
with multiple FETs).

Look at IRC, STM and other makers for a replacement.

I got a bunch of big FETs in precisely that package (4 terminals)
The IXYS IXFN55N50 as used in QSC PL9.0 amplifiers
They have a couple of terminals (Source IIRC) commoned.
It would really help if the OP could read the markings on the device.

Thanks so much to the (non-Aus group) contributors who offered some real
suggestions.

This photo is all I have. I don't have a device, or hi-res pics, just this
one crummy photo (not mine).

I'll start with the IRC, STM, and IXYS mfgrs. and see what they show.

Thanks again for the leads.
--
DaveC
me@privacy.net
This is an invalid return address
Please reply in the news group

 

[Winfield Hill]

DaveC wrote...

I'll start with the IRC, STM, and IXYS mfgrs. and see what they show.

You won't get far without the part number. The SOT-227 parts are
expensive and hard to get, especially in small quantities, so your
best path is to get that part number and let us know. Then perhaps
we can help you find an available replacement part.

Thanks,
- Win

whill_at_picovolt-dot-com

 

[DaveC]

On Wed, 19 Nov 2003 18:07:56 -0800, Winfield Hill wrote
(in message <bph7ls02qqe@drn.newsguy.com&gt:

You won't get far without the part number. The SOT-227 parts are
expensive and hard to get, especially in small quantities, so your
best path is to get that part number and let us know. Then perhaps
we can help you find an available replacement part.

Hmm... I have no p/n's. The MOSFET in question is used in an audio amp
(Danish brand GamuT). I was curious what mfr. was making audio-quality FETs
of this size. GamuT is not forthcoming with any supplier info.

So I'm left with virtual "reverse engineering" (don't even have an sample to
start with...)
--
DaveC
me@privacy.net
This is an invalid return address
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[Walter Harley]

"DaveC" <me@privacy.net> wrote in message
news:0001HW.BBE1849400B1C9B1F0080600@news.individual.net...

Hmm... I have no p/n's. The MOSFET in question is used in an audio amp
(Danish brand GamuT). I was curious what mfr. was making audio-quality
FETs
of this size. GamuT is not forthcoming with any supplier info.

So I'm left with virtual "reverse engineering" (don't even have an sample
to
start with...)

Aha, finally the reason for the original question starts to emerge... but
it's still not quite there; we still don't know *why* you want to know what
the part is. Will you forgive me for suspecting that the right answer to
your *problem* has nothing to do with the right answer to your *question*?

Originally it sounded like your problem might have been "what FET should I
use to replace a blown FET in a device I am repairing." But it sounds like
that's not the case? You've been clear that you don't have the device in
your picture, but you've still not really explained what it is you're trying
to do.

If your problem is "what FETs should I use in an audio amp I am building,"
let me suggest that "whatever was used by the designer of some other
circuit, manufactured in some other country" is not actually a good
criterion, no matter how good their circuit sounds. The sound of an amp is
not due to good-sounding FET's, it is due to good design, which matches the
FET to the circuit demands; and I'm not sure there is such a thing as an
"audio-quality FET", although there are probably some that are better suited
than others to operation in the linear range. A good criterion for
selection would be "whatever meets the specifications implied by my circuit
and is available through the suppliers I have access to".

That criterion implies that you are going to need to actually understand the
circuit you're trying to build, and understand what specifications are
required (or, at least, how the specs affect the performance). Now *that*
is a question that many folks on these groups are prepared to answer.
Having done that, you can then try to search for an FET that meets those
specifications; and again, folks on these groups are excellent at that type
of question.

Of course, if that is not your actual problem, then those questions are not
the appropriate ones. Can you let us know what the problem you're trying to
solve is?

 

[DaveC]

Well said, Walter.

I have come across the statement by some "single-FET" amplifier designers
that when using paralleled output devices that because if their differences
in turn-on characteristics there is some distortion introduced. This is a
given, due to the manufacturing tolerance differences. (We won't argue about
what magnitude this might be, and if it is at all audible.)

By using a single, high-power FET one can reach equivalent results as a
multi-FET design.

I would like to experiment with such a single-FET design, and since not every
manufacturer makes high-power FETs in such a package, I thought I'd start by
fiding out who makes such FETs. Then, ruling out those devices whose specs
are more appropriate for switching duties (rather than linear duties such as
audio), etc. arrive at a short list of devices to start exploring more
closely.

Does that help clarify?

Of course this may all come to nothing more than intellectual curiosity. But
that's what curiosity is for, isn't it, to be satisfied.

Thanks,
--
DaveC
me@privacy.net
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