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TV/VCR/Stereo Troubleshooting/Zenith Z20LA A79 TV no sound


QUESTION: This has stereo output sound and all electrolytics are in great physical condition.  Without a schematic I can not determine the complete circuit. What is the likely problem? A service tech. told me the main board is at fault. I can most likely do the repairs myself with IC or ? replacement.
Thank you

ANSWER: Without troubleshooting and tracing the circuit with a sound detector it would be difficult to know for sure what the solution may be.  For example, it could be as simple a an open wire or ground at the output of the board where the speaker wires connect.

If you cannot do the troubleshooting and diagnosis you are better off to find someone with the technical know how to do it.

I could not find much on this model; I am wondering if the model number you gave is the correct one.  The number you gave seems to be for an old set that may be difficult finding parts if it turns out to be a unique part of the set.

Does it have headphone output jack? If so you could use that output to feed a set of 2.1 computer speakers - which will work fine for the tv.

Let me know if I can provide more.

---------- FOLLOW-UP ----------

SOT SMD transistors
SOT SMD transistors  
QUESTION: Your answer although was not able to pin down the info I was seeking it   was still very helpful.
I do have another question about some SOT SMD transisters. 2 on the board audio circuit are marked A3C8 a 3rd one is marked ASYD3 and the 4th one is marked ALYD3. I have not been able to locate data for these do you have a source for cross reference info.?  I think the ASY & ALY are configured as a push pull ckt. Or drivers for left & right channel.

Thanks for your great prior info.

They are soldered onto the board and are usually very difficult to replace.  SMD stands for Surface mounted device and you can find a ton of them at:

Or you can go to the main web page and search around.  

Even though they might look like resistors, the could be transistors or fets or a resistor network or even a small IC such as an opamp.

You need the service manual to study the circuits and the detailed parts listing, I think.

Zenith is now owned by LG Electronics; you might look into their support pages.


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