grundig: SO302U/S; Stereo/Mono Problem

I have had my stereo working well and went to finally do the refinishing of the cabinet.  I had set aside the electronics during the process, but when I went to put everything back together, the volume level of the "stereo" setting is significantly lower.  When I push the button for "mono", the sound is great.  

I thought that this might be something simple since I had previously changed out all the capacitors and decided to check the resistors, which I had never investigated.  I figured that something around the stereo/mono switch might be the problem.

I tested all the resistors and found a few slightly out of whack, but 3 in particular interested me:

R45 and R46 - Both are testing around 1.8k, while they should be at 3.9k.  While this is odd, I focused my attention on the next issue, which seemed more pressing.

R61 should be 1k, but my multimeter showed 0 flat.  I thought that this was odd, tested the same resistor 3 or 4 times in between testing other ones that all showed the correct value.  Every time that I tested R61, it showed 0k.

I swapped out the resistor with a new 1k resistor, which I tested before installing and it read 1k correctly.  As soon as I soldered it in, the reading on the multimeter showed 0 flat.  Befuddled, I checked the resistor that I cut out and it read nearly a perfect 1k.  

Completely confused, I turn to the group to see what I might be doing wrong.  This might not even be the cause of my stereo/mono problem, but I need to start somewhere.

Thanks in advance!

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You often can't reliably measure resistors. coils or capacitors or transistors in circuit. At least one connection (two on a transistor) needs to be disconnected.

Also except for a few circuit locations tolerances to operate OK are usually much wider than the component tolerances. It sounds like a wiring error or switch fault.

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Hi Michael,

Thanks for the quick feedback.

After looking things over, I have a couple of items:

1. I was applying heat to the shaft in order to loosen the dried grease so that I could manually turn the balance dial.  Not sure if I might have screwed up something doing this, but while I had the stereo apart for refinishing, I thought that I would try and solve this problem.

2. I looked at the switch and the schematics, but am unable to see an obvious place where there's a problem.  How can I test to determine what the problem is?  Are there some existing forum posts that I can reference?

Thanks.

craig.

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