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I have another solidstate headache in front of me that I thought was an easy fix. there was some shorting/noise from the front panel controls being loose. Pops and noise when pushing on it but I don't actually recall if this hum existed when it came to me as I didn't pay much attn (oops) figuring a simple broken joint etc... Well I fixed the shorting issue via a couple of bad joints but I'm left with this bad hum.
Touching the cable sleeve,pots.etc..quiets it. checked for ac ripple at the filters , didn't seem to be flucuating too much and not very high. Have checked major ground points again and again (though may still be a bad "in circuit" ground somewhere... an ic,res,cap etc...) checked all jacks. seems no significant dc on outputs. Also touched up solder around filters which seem fine and all jacks.
The hum does seem to have some hi gain trash in and the reverb has some static in it so I've looked around these areas a bit.
While testing vltgs and audio probing i noticed a horrible loud square wave sounding signal (no working scope
) coming from pin 6 of IC3 a tl072 which is the stage between the 2nd channel gain and volume. This doesn't seem right but since the hum affects the clean or normal it may be nothing. finally there seems to be some major farting of the speakers (both speaks both outputs) when volume is up and really digging it.
I know this may be one of those hard problems to track down but any ideas to get the ball rolling again for me would be great
Thanks
Touching the cable sleeve,pots.etc..quiets it. checked for ac ripple at the filters , didn't seem to be flucuating too much and not very high. Have checked major ground points again and again (though may still be a bad "in circuit" ground somewhere... an ic,res,cap etc...) checked all jacks. seems no significant dc on outputs. Also touched up solder around filters which seem fine and all jacks.
The hum does seem to have some hi gain trash in and the reverb has some static in it so I've looked around these areas a bit.
While testing vltgs and audio probing i noticed a horrible loud square wave sounding signal (no working scope
) coming from pin 6 of IC3 a tl072 which is the stage between the 2nd channel gain and volume. This doesn't seem right but since the hum affects the clean or normal it may be nothing. finally there seems to be some major farting of the speakers (both speaks both outputs) when volume is up and really digging it. I know this may be one of those hard problems to track down but any ideas to get the ball rolling again for me would be great
Thanks
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