speaker selector switch is only thing between the headphones and the speaker terminals.
try clip leads to short across it? It's rotary and hard to clean.
Also try the other set of speaker terminals, in case their ground is dicey.
and clip leads from their - side to a good chassis ground also to check - speaker terminal's ground.
Ohmmeter isn't as good a test as solid clip leads in this situation.
Thanks MTF. Was thinking reflowing terminal grounds might be the fix.
clarify something - when the speakers are distorting, if you listen to the headphones are the headphones OK or distorted. They BOTH have to be ON at the SAME time for this test.
If the headphones distort while the speakers are distorting, it is the amplifiers fault, not the wiring or switches.
Now if you have to turn up the unit to hear the speakers, and turn down the unit when listening to headphones, that changes the volume of the signal in the amplifier. So if that is the case turn up until the speakers distort, THEN TURN OFF THE SPEAKERS and see if the distortion in the headphones continues or goes away.
In other words be aware of any changes made to the volume control when doing this testing.
clarify something - when the speakers are distorting, if you listen to the headphones are the headphones OK or distorted. They BOTH have to be ON at the SAME time for this test.
If the headphones distort while the speakers are distorting, it is the amplifiers fault, not the wiring or switches.
Now if you have to turn up the unit to hear the speakers, and turn down the unit when listening to headphones, that changes the volume of the signal in the amplifier. So if that is the case turn up until the speakers distort, THEN TURN OFF THE SPEAKERS and see if the distortion in the headphones continues or goes away.
In other words be aware of any changes made to the volume control when doing this testing.
I bend a j-hook into the end of the deoxit straw (small wire into core, warm up, bend, cool, remove wire) to get up from the pc board connections where the wafer is almost always is open.
WD40 and other straws are the same size. You would not believe the convoluted sculptures I have done with the straws in the past...
with headphones alone (I know it's hard - gets loud quickly: are the headphones distorting because of over drive or is the signal distorting) is there a volume point where the distortion gets nasty quickly?
2 things I am exploring here:
1. distortion related to speaker load, mostly independent of volume
2. distortion related to volume, where half the amplifier channel isn't working, it can carry lower volume signals ok, but when more is needed...
Do you have a DMM? Feel comfortable trying to make measurements at transistor leads? I'll tell you where, but are you confident of probing in there. We WILL insulate all but the tips of the probes so slipping isn't as much of an issue.