Toshiba 32A10, worth pursuing ? Or do I trash it ?

[chevelle_nut]

My Toshiba 32A10 chassis number TAC0019 is having what I can describe as pin cushioning issue on all inputs. I have read many posts about convergence problems and such. I am wondering if it is a simple matter of swapping out caps, replacing chips (and resistors ??) a combination of all or is there more to it than that ? i.e. service mode adjustments, scopes and what not. I can swap parts but I am not really equipped to do much more than that.

Thanks in advance,

[Wizard]

Re: Toshiba 32A10, worth pursuing ? Or do I trash it ?

32"? Check the soldering on pincushion circuit appox in middle, fat transistor with small heatsink on it that is near a coil in series to the horizontal circuit via 2 diode pincushion on another heatsink near horizontal drive transistor.

Cheers, Wizard

[chevelle_nut]

Pincushion parts

Yes sir it is a 32", been a great set (forever).

Are you serious ?! It is probably just a solder joint, or should I get a replacement transistor on order ? I have not even had the case open yet.

You really are a Wizard, a truly amazing one at that. Thank you again Sir, I'll post back once I do the exploratory operation


BTW, the Samsung 710MP you guided me through still works great - everyday.

[Wizard]

Re: Toshiba 32A10, worth pursuing ? Or do I trash it ?

If it acts up and reacts if given thump test, more chances of able to get it fixed with solder job. Just be careful. No need to disconnect the thick red cable to the tube suction cup. Unplug speaker connector on the mainboard to get chassis free so you can pull, tip up and lean it against TV.

If not, follow with your multimeter on ohms range with power cord UNPLUGGED! You will eventually find one that is shorted, or open.

The area is where either 2 big diodes or a 2 diodes in a package like a transistor package with each is poly (not polymer) capacitors in parallel with each diodes. Diodes are in series across ground and horizontal transistor's output, with middle node of both diodes connected to a inductor coil, then to another transistor usually on a heatsink. I usually either find bad solder in the pincushion drive circuit or one diode failed means one poly capacitor is bad which gets replaced. Not big deal.

Note: the "top" diode with own diode connected to the horizontal output is not the problem (causes no picture!) and is for the horiziotnal damping/oscillating. While bottom diode with cap attached to the ground IS the pincushion part of overall circuit. When that pincushion diode shorts, you get bowed picture, same with no pincushion drive (bowed but not as severe).

See what you can.

Similar circuit for example:

http://www.fixya.com/support/t115987...9n50_trinitron

Cheers, Wizard

[chevelle_nut]

Re: Toshiba 32A10, worth pursuing ? Or do I trash it ?

O.K. I got the chassis pulled out this a.m. And just as you said there in the middle of it all is a bulged cap. It is a 10uf @100v KME series, when I search Digikey for replacement they all come back is a much smaller package ! The existing one is about 5/8" diameter and 1" tall. As for the diodes, I am still looking for the ones you describe. There are a few heatsink mounted packages in the area, but I am having trouble crossing them also.

I have a pic, but I need to take a refresher course on how to post.

...doh.

[chevelle_nut]

More pictures and some observations

There is a dark area on the board around the 2 "transistors?" marked C3852. The dark area extends across the circuit board from the HV section. I do not believe these to be the diodes in question, as the circuit board is labeled BCE. I also included a "satellite" shot of the entire board for reference.

Thanks again for all your help.

[Wizard]

Re: Toshiba 32A10, worth pursuing ? Or do I trash it ?

The large heatsink with the 2SD2493 is the pincushion transistor driver driving the coil then in turn goes to the diode divider with pair of capacitors paralleled with each diode in the horizontal circuit. The other two smaller transistors probably is the driver for the large transistor or used everywhere else. Need the solder side PCB so I could trace.
all the way to the horizontal circuit in 2 or 3 overlapping photos.

Cheers, Wizard

[chevelle_nut]

A picture is worth a 1000 words, here is a novel

I took shots from the pincushion (169), the area all the way to the horizontal circuit (170,171), and the area that has the 2 C3852's (172), then a broadview of the whole board (173), and the I think the pincushion area with the diodes and poly's you mentioned from the topside (174). It looks like D461 in picture 171 is the questionable diode and the heatsink solder joint to the board looks poor. How do I go about checking the poly caps ? (C439) The right side one in front of the diode looks to have had a thermal event at some point in it's life, it looks darker and not as shiny as the one next to it.

[chevelle_nut]

Re: Toshiba 32A10, worth pursuing ? Or do I trash it ?

So let me see if I understand so far... the big gooey electrolytic in the middle is NOT the pincushion problem ? Or is the fact that the cap has gone bad merely the result of the diode failure ?

[chevelle_nut]

How come the replacement capacitor is SOOOOO small

The listings I keep getting for a replacement of that 10uf 100v cap are about 1/10th of the size of the original. Am I missing something here? I am thinking of bumping up the voltage rating on the cap just to get some bulk.

[chevelle_nut]

Do you recocognize ME?

Hi I recently blew my goo inside of poor 'ol Chevelle_nut's TV set. Now he wants to replace me. I am bout 1" tall and 5/8" in diameter, I am brown and have the following distinguishing markings:

KME 100V 10uF

on my backside I read:

(M)105°C 0(2) OB

Unfortunately the owner can not believe that my "replacement" is only .248" in diameter and less than 1/2'' tall...

If you can help him identify a replacement from these recent mug shots please post ( or p.m. chevelle_nut )

Thanks,

I am missing my old tv already.... <sniff
and what the hell IS that SMELL !!?

[chevelle_nut]

As luck would have it...

I was out on a customer site and as I left I noticed an electronics repair shop on the edge of an industrial park. I stopped in and purchased a 10uf 350v cap (still physically smaller than that which it replaced). Popped her in there and cleaned up a couple of other solder joints.

It IS ALIVE !!! No pincushion so far !

I did take a better pic of the trace side of the board from the cap to the HOT. I also pulled the diode on the heatsink and checked it and found 1 other that did not test right in the board, but once out checked fine.

Thank you once again Wizard, without your guidance this one was destined for the recycling bin. I would never even have opened the case up on my own.
( I have WAY too much 'respect' <also read fear> for the HV section to leave it exposed).

Phew, mission accomplished.

[Wizard]

Re: Toshiba 32A10, worth pursuing ? Or do I trash it ?

Awesome. I bet this cap is a filter for B+ supply for the horizontal circuit thru flyback tranformer. Unfiltered must had made voltage to sag enough to bring pincushion out of specifications.

You'll need to go back into TV and resolder the hot (thermal) stuff as I see many bad joints.

Cheers, Wizard

[chevelle_nut]

Re: Toshiba 32A10, worth pursuing ? Or do I trash it ?

I did do some touch-up and cleanup whilst I had the iron hot and the swabs out anyway. There were a few joints that did not photograph well but had decent enough connections. I did remount the lone diode that did not check out 'in-circuit' as well as the diode with a heat-sink ( I pulled off board to test). I also touched up the GP transistors heat-sink mounting pads. Unfortunately I did not take pictures of the completed work. I really should have taken the pictures of the trace side without the board support in the way. I was VERY nervous about taking the board off that support, but the cap leads were right next to a brace. Also there was a fair amount of flux on some of the joints still, I assume it was from factory like that as I am original owner and it has never been in for service. I cleaned as best I could. All is well for now. Here is one pick I took with the new cap leads yet untrimmed that shows the whole area to the HV section. Then the before picture of the pincushion, next is the money shot - no pin cushion !!!