Zenith 25DC56 lost audio
1 Attachment(s)
This is the Chromacolor that I got at an estate sale in April of 2016. I had it repaired in May of that year, and it has been working perfectly since then. Just yesterday, for no reason, I turned the set on to watch The Simpsons, and the audio was almost totally quiet. I found that if I turned the volume control up rapidly, I could get some weak, scratchy audio for a second or two, then it would fade away. I tried that again tonight, but there was even less audio, if any at all. I checked the obvious first, checking the speaker connections, then I tapped around on the audio module that sticks up and was able to get some loud humming when I tapped certain places with my screwdriver. I then tried moving the IC to reseat it in the sockets, and that didn't do any good either. I have another set with this chassis I could pull the IC out of, but it's inaccessible at the moment.
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Most common on these & hybrids was the output transistor.
Usually would make popping noises first. Can use 2 different pks's that are interchangeable. OEM's were a kit that also had a VDR for improved reliability. IC's also went sometimes 221-45 ?? easier to change too. IIRC gotta go under for output. 73 Zeno:smoke: LFOD ! |
Later today I'll try to snap a pic of the audio section of the schematic. Voltage measurements should be telling.
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ECG124 or ECG157 IIRC.
Boy is it getting hard to remember. 73 Zeno:smoke: LFOD ! |
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Here is the audio portion of the schematic. The output came out a bit blurry...I'll retake those tomorrow if you want.
https://farm1.staticflickr.com/969/2...5b0aa9ce_n.jpg https://farm1.staticflickr.com/909/4...afbc69c9_n.jpg https://farm1.staticflickr.com/946/2...000aa133_n.jpg https://farm1.staticflickr.com/956/4...b42083e8_n.jpg |
How did YOU end up with a schematic for MY television??? These are the questions we should be asking.
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Unfortunately, this set will have to be placed on the back burner. My CTC-28 died last night for absolutely no reason, and that's what I'm going to have to worry about for the time being.
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Finally fixed the audio on this TV. I took the IC out of my other 25DC56 set and put it in this one, and that fixed it.
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