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#1
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It's a big CRT set, 32 inch screen. Just died. When I try to turn it on the relay clicks, and about 5 seconds it gives up and clicks off. No TV sound or picture (though the CRT would not have had time to warm up anyway). Without removing the power plug, subsequent attempts to turn it on do nothing. Pull the plug and reconnect some time later, I get the 5 seconds as above and it gives up.
Before it died, the horizontal width was getting narrower, about an inch of CRT screen on the right wasn't getting any image, aka, was black. Been like that for months. This set weighs more than I do, I'd guess, and that would make getting the back off really hard. If it's likely just a bad power supply cap, I could replace that. If the horizontal output stage died, that likely will make me give up on it. What part failure does this sound like? TIA
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#2
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Sounds like a cap in the horizontal circuit failed and it eventually took out the HOT.
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#3
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Im so sorry buddy!!
We love our TVs like crazy.....I hope you can get her going again
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#4
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Yup sounds like the HOT shorted. You have several other
hurdles if it is. What caused it. Did it damage the power supply. Big sets are a pain to work on unless on a bench with space & lots of light. Also Sams doesnt list it ( got a chassis ##?). The only things I remember with newer Pannys was HOT's, the usual PC cons at hoz drive transformer & pin diodes. If you go further post a few chassis photos to familiarize us & maybe we can help. It may be time to put it down sorry to say. You can get these at Good Will etc for next to nothing. Just try to get an older one from a big maker. I would stay away from Zeniths, & NAPs. Sets before the late 90s wont be rebadged Chinese garbage, more likely the real thing........ 73 Zeno
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#5
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Pincushion diodes and horizontal outputs were a problem on the CRT panasonics as well as power supply electrolytics and IC's.
Also, look around the power relays. Bad connections are a problem there. While you are in there, look over the caps around the vertical IC and the vertical IC connections. They were problematic. Can you post a picture of the chassis. Also, is it the Prism or the TAU set. The TAU had CRT troubles (went gassy quick) and power supply intermittants that was connections all over the circuit board. |
| Audiokarma |
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#6
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It's this model ct 36L11e
Picture when we first got it.I took a quick peek thru an opening at the chassis, the few big caps I can see don't look bulged. The back helps support the set, making it difficult to remove.
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#7
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Not to worry. When you pull the back it will be a little more
front heavy so keep that in mind. Also if the speakers are on the back you gotta unplug them. Once off you can slide back the chassis & do some checking. Zenith 26kc20 pointed out some other common problems. Even if they are not the cause they should be checked along with a good looking over for PC cons & swollen or discolored caps. With the back off its also easy to move. Just hug the set from the front & grab the edges to move. Just watch the neck! Putting the back on agn you have to line things up but most the time they fall nicely into place. Sometimes you may need a second helper to tip the set a little. good luck Zeno
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#8
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I opened the back and pulled the circuit board. AFAICT, the HOT transistor isn't shorted, at least from emitter to collector. I measure 40 ohms both ways from emitter to base, after I pulled two wire jumpers that disconnect the emitter and the base from the rest of the circuit.. It's a 2SC5339 and I looked up the data sheet on line and it turns out it has a built in 45 ohm resistor between these points, so maybe it's not blown..
No cap looks by sight to be spilling its guts. And I tried resoldering the horiz output transformer terminals on the board, but the set still shuts down in a few seconds, as before. A sticker on the HOT heatsink says: "serial number LE20210034 GP342". Other than that, I don't see any identifications.
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Last edited by wa2ise; 09-07-2013 at 02:57 PM. Reason: update |
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#9
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Thanks all for your help, but it seems the flyback developed an internal short. So I'm gonna give up on this set and will scrap it for parts.
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#10
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I understand your frusteration....
Its too bad you cant discover WHERE the short happend
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| Audiokarma |
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