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Quote:

Originally Posted by zeno (Post 3167831)

Dont know why the A is there but use it. They always change the number
if different. The A may be a minor revision.

73 Zeno:smoke:

Seems there were many revisions. I have another whose box is marked 9-103-04-R. The "R" does not appear on the module.

Both came from that bargain basement stash you pointed out a while back.

Rather than replace the module, do you have a Sam's for the set that might give you DC voltages around the audio IC in your pic?

Are there separate discrete transistors for audio IF, or are all functions built into that IC?

Another thought is look up that IC by number online, which should give clues as to the expected voltages and waveforms around that IC. If a DC voltage is off, either a resistor drifting high, or a leaking /shorted cap might be the culprit.

Is the IC getting hot?

Also, check the inputs to the module. The problem may not be the sound module at all. I'm thinking there will be sound "takeoff" point coming from the video IF, but I am generalizing and not as familiar as others with 70s SS sets.

There are not that many parts on the audio module. Can you check for ESR on the electros, as well as resistor values?

Your cleaner spraying of the volume pot should have changed the sound (even if only slightly) if it were the problem. Still, they are very problematic...

Good luck! 😀

Quote:

Originally Posted by wkand (Post 3168057)

Well I interchanged the sound module with the one JonA sent me and it has produce no change whatsoever. So I GUESS it has to be the volume sliding pot. Will take it a look at it before doing anything else.

Quote:

Originally Posted by zeno (Post 3168001)

Just looked at the photo. Looks like this has wires for
the VC & probably audio mute between channels or tone.
Does it have a tone control ? Anyhows on the IF strip
it shows where some of the wires go, check the layout
chart also & be sure every things where it belongs.
Looks like it has an oval SPKR so no bass cut cap.

I will see if I got the manual but my squaw is on vacation &
I just bought her a new car so she wants to go places, not
fix TV's !!! I will get to it though........

BTW Analog meters are best for some tests & alignments.
If you got one unhook the VC & see if it gives smooth ops
across its range. The value should be printed on it. Zenith
used heavy US made sliders but they still sucked like
all others compaired to regular pots.

73 Zeno:smoke:

Well finally got around to spray that thing with WD40. Didn't work. I also checked if it was giving smooth operation all the way with my multimeter (unfortunately I only got an el cheapo digital one). Pot SEEMS to give smooth operation but I am unsure.

I read 0 - 75k ohms on that pot, Zeno does that sound about right to you?

If so, will try to substitute with a rotary one just to see.

Thanks!

75K probably OK but seems like a high value 2 me.
Try hanging a different speaker on it also, could
be the voice coil is stuck. Unplug the in set SPKR for test,
use almost any SPKR for the test.........

73 Zeno:smoke:
LFOD !