Panasonic CT32G21U Dead

[Toasty]

Panasonic 32" TV
CT32G21U
ALEDP276

Dead.

Found chassis fuse blown. Jumpered and applied power via isotap. Had clicking of relay as it tried to energize circuit but you could hear it overloading and recycling every 3-5 seconds. Obvious short as main power resistor was getting very warm with only 50v applied to chassis.

Found:
- Main 4A fuse blown
- BU2508DF shorted - HO transistor

Removed transistor and problem remains with overload.
Power supply & B+ diodes checked okay.

Tracked overload to SMPS chip STK730-020.

Found:
- Dead short from power input on IC (pins 11 & 12) from transformer, to ground (pin 3).

Suggestion I found was to upgrade the STK730-020 (145w) to a STK730-150 as it's a higher wattage (170w) unit. Should I go all the way to the STK730-080, 210 watt?

What else should I be looking for as a possible problem in this set?

I have found the replacement IC's ranging in price from $5 to $30. What gives?

Reliable source for these components? MCM? MAT? ebay?

Thanks for your input.
Toast

[Wizard]

Re: Panasonic CT32G21U Dead

Careful. There are fake STK ICs.

Buy from reputatable supplier.

And this chassis have bad issues. Watch out for that and try to find panasonic tech and see if you can get bulletin info on modifing this chassis (involves few components in the power supply for the base drive circuit for the HOT).

And yes, full of bad caps in the SMPS!

I had bad luck with these using STK 730 series pananonic chassis. 2 out 5 kept frying after a time.

Cheers, Wizard

[i4004]

Re: Panasonic CT32G21U Dead

how old is that tv?

[Toasty]

Re: Panasonic CT32G21U Dead

@i4004
Set is 12 years old.

@Wizard
I am looking for a reputable supplier for these parts. Whom do you use or recommend?

You are aware of the modification, but I assume you did not perform that repair? Any info on that?

Bad luck with the STK730... do you suggest I use another type?

[Wizard]

Re: Panasonic CT32G21U Dead

STK 730 is engrandered list on ICs and dying off in the remaining stocks.

http://www.bdent.com/search/search.jsp?contains=STK730&category=ALL&submit.search=Search!

B & D is one you should get for STK ICs. Get 060 or 080 as they are all what they have now and plenty of headroom over this little wimp 020.

The modification info, like I said in other posts, we had huge problem dealing with panasonic back then and they wouldn't cooperate with us at all on inquiries.

And YES there is modification for this issues. See if you can get in touch with other techs who managed to get ahold of this info.

Here we no longer fix panasonics as they are getting too old and income hard to come by because customer are unwilling to pay because cost of repairs doesn't drop on panasonics compared to other brands due to their quirks and high risks of call backs ESPECIALLY dead sets in first place. We didn't pull out, panasonic did pull out saying not enough service. But it is the customer & shop relationships with panasonic that sucked.

Like I said as well, if you have a brand maker that is great support to work with, then it is much easier time and profitable, quick service and everybody are happy all around.

Cheers, Wizard

[tmwalsh]

Re: Panasonic CT32G21U Dead

Wizard:"Here we no longer fix panasonics as they are getting too old and income hard to come by because customer are unwilling to pay because cost of repairs doesn't drop on panasonics compared to other brands due to their quirks and high risks of call backs ESPECIALLY dead sets in first place. We didn't pull out, panasonic did pull out saying not enough service. But it is the customer & shop relationships with panasonic that sucked."

Do you suppose that is why they just ceased production of televisions?
tom

[Wizard]

Re: Panasonic CT32G21U Dead

Tmwalsh,

Not much of it can be fixed due to not very many come across here, nearly all we can could do is vertical stuff and resolder stuff and HOPE the horizontal circuit did not blow!

We used to be authorized servicer of Panasonic and dealing with warranty stuff is like pulling teeth outta ornery horse. They simply left us saying not enough frequency service to worth their time with us. :P How nice.

The direct view CRTs of panansonic doesn't win any prize on sharpness but they do last.

Cheers, Wizard

[weirdlookinguy]

Re: Panasonic CT32G21U Dead

Panasonic didn't cease production of TV's, that was Pioneer.

Panasonic makes some damn good TV's. Our new(ish, last year's model) 42PX80U plasma has all japcaps on all the boards inside. Might not have meant much 10-12 years ago, but is increasingly impressive today.

[tmwalsh]

Re: Panasonic CT32G21U Dead

Mr. weirdlookinguy, you are correct, and I was wrong. I hadn't seen a Pioneer set ever, so my mind must have filed it under "P" for panasonic. Haven't seen a Panasonic in a long time either, but remember taking DEC pdp11 canned training on videotape using a 19" Panasonic. We all tried to use the other TV setup as it had a better display. That, before there were even retail Beta machines, was the last Panasonic TV I remember seeing.
No wonder I can't keep track ...
tom

[Wizard]

Re: Panasonic CT32G21U Dead

That's Loooong ago! DEC ceased to exist in 1998 so you would had taken training around 1995 or 1990's even eariler.

DEC by then was damn good stuff. Seriously.

Cheers, Wizard

[zandrax]

Re: Panasonic CT32G21U Dead

PDP11? Way older than 1998: maybe 1988

Zandrax

[Wizard]

Re: Panasonic CT32G21U Dead

DEC existed long to that 1998 and for nearly 18 years they had VAX machines. One very famous use I liked very much was Notes forums. All text and no graphics. Fast.

Cheers, Wizard

[zandrax]

Re: Panasonic CT32G21U Dead

Digital Equipment Corporation a.k.a. Digital (DEC is a more formal acronym some people hate) started manifacturing minicomputers in mid '60s, the famous PDP line; the PDP11 is the most diffused 16 bit PDP and was officially sold from 1964 to 1997 in different models and revisions, but since late '80s it suffered from competition of the low models of Digital VAX and, of course, from microcomputers for common tasks.
The 1998-1988 sentence was supposed to be a pun: anyway never mind

Zandrax