Panasonic CT-1310M keeps blowing horizontal output transistor

[vol.2]

Originally Posted by luRaichu

Please, enlighten me to any other repair shops or techs in Maryland or Virginia. I cannot bring myself to work on this set anymore.

Honestly, no. I don't know of anyone I can fully recommend. Danco is a great tech, and he won't rip you off, but he is retired and doesn't care about taking jobs unless they are interesting to him, and he has told me on numerous occasions that he especially doesn't like taking in jobs that other people have been messing with.

There's no one I'm aware of in Maryland that will take in a CRT and can be trusted other than him (if he will do it), and I don't think he's too likely to touch yours, and if he did you would be paying out the nose for it because he charges hourly and his time is valuable.

There used to be a LOT of guys in the area who would do it, but they all retired and/or died like 20 years ago. Danco was a late arrival, and then he made most of his living handling all the audio/visual equipment for the National Zoo, and doing big important restoration jobs for museums and stuff like that, so he could afford to keep the small neighborhood shop running.

I think you're going to have to look in Northern VA, there's a much better chance of finding someone over there.

But seriously, this particular TV you are working on isn't worth what someone competent is going to charge you. You could easily be looking at over $100/hour for that kind of thing, and it's a basket case.

My advice is to keep cracking at it, or let it go. And that doesn't have to mean getting rid of it; you can mothball it and get back to it after you have more experience.

Also, you might want to give some thought to getting some better equipment if you want to mess with this stuff more. At the very minimum, an isolation transformer is really important as a safety precaution. Without one, your line leads are connected directly to the grid on the neutral

[luRaichu]

Originally Posted by vol.2

this particular TV you are working on isn't worth what someone competent is going to charge you. You could easily be looking at over $100/hour for that kind of thing, and it's a basket case.

I think it's worth it. Almost nobody has these CT-1310s anymore (Well, my neighbor did, until I showed up a month ago). We'll just have to see what Shipley's says. After all, they appear to have rave reviews and are still in service.

If I must continue working on this set, the way forward would probably be replacing transistors and diodes. After all, the HOT is a big transistor & was blown when I first got this set (which is why it'd been thrown out).

[ARC Tech-109]

So what makes this set so valuable?

[luRaichu]

I just called up a bunch of shops and techs in Maryland and nobody in the area can or will work on my Panasonic set. I guess I'm still on my own here!
So, how should I test, order, and replace bad diodes/transistors in the PSU/Horizontal circuits? Those are the only problem I can think of.

[ARC Tech-109]

[QUOTE=luRaichu;3257145]I just called up a bunch of shops and techs in Maryland and nobody in the area can or will work on my Panasonic set.

This doesn't surprise me really, the number of "TV-Radio" repair shops remaining are but a small fraction of what they were a quarter century ago. Most of those techs are retired or have become silent and the few that are around know little to nothing of the legacy technology. I grew up in TV shops having them in the extended family, both had closed up by the mid-90's because the business dried up.

So what to do about your ailing Panasonic Color Pilot:
If it was me I'd go back over my work again after a short break, say a week or more to get it out of my head.
Starting over with in-circuit checks of transistors knowing the junction is about 0.75 volts, I use a Fluke model 77 DVM that I've had since the mid-80's and it has a real diode check function that shows the actual junction conduction voltage. Okay so the semiconductors all show the correct forward drop in their respective directions I then move on to capacitors. You said that you have replaced a majority of electrolytics, what did you use? This is very important as the vast majority of chinesiums are bad right out of the box. When I say bad I mean internal current leakages and high ESR values. More often than not I will use salvaged capacitors out of the last generation surround receivers that had worked but replaced for an "upgrade" and these salvaged units are performing well. One of my present 16:9 monitors is a Panasonic CT34WX54 widescreen CRT that is presently running salvaged electrolytics along with ALL of my Sony PVM-5300 triple monitors I use for production work. 1984 vintage take-outs from the local FOX affiliate with millions of hours they got recapped with salvaged caps and work as they should. Have you gone over the top of the board and actually verified each capacitor is the proper value according to the schematic AND the polarity is correct?
Okay so we "think" the electrolytics are good being name brand parts like Nichicon then I'd move into the various supply voltages following the schematic. With the horizontal transistor blown I'd remove it from the circuit and sub in a 40-watt incandescent lightbulb between the emitter & collector to load the main part of the power supply, no you won't have any sweep but this is not important at the moment... an oscilloscope however would be most helpful and the reason for this is even without the HOT in place there should still be drive available on the collector of Q501 unless the failsafe has an issue. Without horizontal pulses coming into the failsafe it shouldn't trigger a shutdown. How about voltages? We don't need exact numbers here, +/-5% is a good working margin. That being said what are the voltages going on the various circuitrace flags listed on the schematic? If they're within the spec tolerance how about at the various collectors of transistors or the VCC point of IC301? I've been trying to follow along the schematic you posted the image of but the hosting site is a pain and I can't see the whole thing.

The problem here unfortunately is a lot of variables have been added and it's become a circle of tail chasing with the only solid result being shorted horizontal output transistors and frustration. Replacing capacitors was a necessity, you pulled one that was missing a lead that had corroded away however without the necessary test equipment you're still trouble shooting from the hip.
Those flybacks have been known to short & fail, the ones I've experienced won't even run long enough to light up the screen but that's not to say it couldn't while eating expensive transistors along the way.

I've been going through all of your posts trying to put together a summary of what has been accomplished to this point. Electrolytics replaced, resistors tested and a complete resolder. This is the one that I'd focus on first, with a magnifying glass and lots of time. All it takes is a bridged pair of pins on an IC or between two close spaced leads to throw everything into a tailspin. Have you carefully done a visual on the board and I mean out of the chassis? Don't like the smell of flux? Sorry but it's a fact of electronics repair and you will have to deal with it. Personally I'd pull the board completely and do a de-flux using the fuel additive "Purex99" in the red bottle, that is 99% pure isopropyl alcohol and that will take ALL the flux off with a little scrubbing with an old toothbrush. From there I would be looking at every connection following the traces around and giving attention to the closely spaced leads for any sign of a bridge. This can take some time... a lot of time. I'm also seeing a lot of frustration and impatience, I pick up on these things. It's this frustration and impatience that makes a big pile of smoked parts.
What I can't do is fix this over the internet despite my past experience with them, until I actually get my hands in something and a feel for what's going on all the explaining in the world is not going to help, this is why I say to go back on all of your work starting with fresh eyes after taking some time away from it.

Options and I'm being serious here. One is you could keep at it and take things step-by-step. Two is finding a someone willing to work on the set but that sorta defeats the prupose doesn't it? I mean you fixed a McIntosh right? Three is you could box it up and donate it to me so I can fix it and add it to my collection saving the remaining horizontal output transistors of the world from certain destruction. I'd even pay the shipping.