Green convergence problem on Panasonic widescreen rear projector

[rpm1200]

Well, my main TV decided to start acting up last night. The green convergence is out, all over but mostly on the right side, and the green is bowed in on the right side as well. I used the on-screen convergence adjustments to deliberately mess up the red and blue to sorta match with the green, here's what it looks like now:


It is a Panasonic PT-47WX49E, chassis DP820, made in 2001. Up to yesterday it has never given me a bit of trouble.

Are there any known issues with convergence in this chassis? I'm going to try to start checking it out tonight. Also, if it is operated the way it is now, will other parts get damaged, or is it OK to run? The kids might revolt if they have to go without DVDs for a day or two.

[brokenbroken]

I had that same set with the same problem. I replaced the two convergence IC's and a resistor that was open near one of them (don't remember which resistor off hand) and that solved the issue.

[rpm1200]

Thanks for the advice. I'll be pulling the convergence ICs soon and I'll check the resistors out at that point. Two questions...

1. There are a lot of conflicting opinions out there concerning replacement of the STK392-110 convergence chips used in that TV. Some say go with the original part numbers, some say use the -120, -150 or -180 instead for better longevity, or even the STK394-160E... Supposedly the -110, -120 and -180 have the same specs, and the -150 is rated for higher voltage and current. Every individual seems to have a different preference. I suppose since these lasted since 2001, I really don't have anything to complain about. Any suggestions?

2. There are a lot of electrolytics around the convergence chips. Should I pull them and check for high ESR, or is that a waste of my time?

Thanks again, Rob

[rpm1200]

Well I can provide an update based on tonight's work... all 12 return resistors measured good. I used a function generator, scope and a couple of resistors to check the caps' ESR while they remained in-circuit. There are a number of 16-volt 100 uF and 47 uF caps that appear to have high ESR, and there are other 35-volt caps that test fine, so I think I'm going to replace the 16-volters with 35-volt caps when I replace the ICs. I think that's enough for tonight...

[Geoff Bourquin]

I have not seen the caps fail on those, but sometimes one or two resistors (and sometimes none, depending on whether the IC went went open or shorted). I have used STK394-160E on those, but they are getting scarce these days. I NEVER use the -110 on anything. Too light duty. These days I usually use STK392-150, as they are fairly tough and still available. Make sure they are GENUINE SANYO Ics. There are a lot of fakes out there, and they will usually fail in short order, and may take several of those resistors with them. A quick test, take a Q-TIP with a dab of acetone on it and see if the number rubs off of the part. If the number wipes right off, it's fake.

[rpm1200]

Thanks for the help, Geoff! Do you have a favorite supplier for the ICs? I usually buy from MAT but I wonder if they sell the cheapo non-Sanyo ICs... they want about $10 per IC for any of the STK392s.

They also have a "Hitachi Repair Kit" that includes two STK394-160Es for about $30, and the chips look like genuine Sanyo to me:


Thanks, Rob

[Geoff Bourquin]

If they're real kits, I'd go for it. I've had trouble getting them lately. The last ones I ordered cost me about $34 +s/h if I remember correctly.

I have seen a few posts elsewhere that the 394- series is not always successful as a sub for the 392- series, but I've had no problems. The 394s have better frequency response which seems to make them run cooler at the higher scan rates used in the HD ready sets, but I suppose that could make them unstable and oscillate if things are just right (or just wrong?).


I usually get this kind of stuff from PacParts in Portland (pacparts.com). From there to here is usually overnight even by UPS ground and the guys there have always been real helpful.

[rcaman]

matt electronics are yall out of your damn mind. they are the bottom of the barrel chinease liquidators. nothing but pure junk. and i have been in business for 30 years i know........ how stupid. steve

[rpm1200]

That's why I asked! I am not a pro by any means.

I found a really good writeup on convergence IC replacements here: HT Shack. They recommend only a few vendors and say the rest sell Chinese junk chips.

Now I'm leaning toward Acme Electronics. They seem to be a pretty good vendor, and only charge $13 for the genuine Sanyo STK392-150. Better than the $60+ Encompass (Tritronics) wants for a single STK392-110 with a Panasonic part number. Acme also has some good prices on Sanyo low ESR caps which I could use to fix some broken LCD monitors with crappy, leaky Chinese caps.

So Steve, who do you go to for these parts and what's a reasonable price to pay?

[Zenith26kc20]

I've used Acme for a number of things and had good luck. I say the same for generic replacements. If you want a comeback in short order, they will get it for you.
I've also used Tritronics for IC's also.
Watch the capacitors you use. I like Nichicon for electrolytics. If the name is weird, don't use em (Capxion, Trutech)!

[rpm1200]

Quick update, it's fixed now. I ordered a set of STK392-150s from Acme. I did not bother doing the caps, the OEM ones are Matsushita and don't seem to be in too awful shape. I did check the STKs and their lettering stayed on just fine when I wiped them with a bit of rubbing alcohol! The TV is working fine now. Hopefully I won't have to put a new set of convergence ICs in for another 9 years or longer...

Acme was a pleasure to deal with. I sent in the order just before midnight on a Thursday and Acme had it in the mail by 4 PM Friday - got it Monday with standard delivery.

Now I'm working on those IBM LCD monitors with the awful HERMEI caps in their power supplies... all leaky (but look good physically)... replacing them with Sanyo low-ESR caps.

[freakaftr8]

have seen trouble with those 16v 100mfd caps in a toshiba rp on the hyper board. Hope he set stays goin for u.