Hey y'all, I'm trying to see if I can reduce the hum in the reverb circuit on my Ampeg G-12 Gemini. It's always been there and is live-with-able, but I'd be great if it wasn't there.
Here's how it behaves:
-Reverb pot directly affects hum volume, 0 = no hum, 10 = lots of hum
-Disconnecting reverb tank eliminates hum
-Removing V7 eliminates hum
-Toggling footswitch does NOT affect hum
-Removing V6 does NOT affect hum
One thing I noticed is that the schematic appears to show a ground lead from both sides of the reverb tank. One of the leads from my reverb tank has the shielding wired to ground, but on the other one the shielding is just trimmed off. There appears to be a through hole to ground adjacent to the reverb signal line that was never soldered? However, when I tried running a jumper from the cable shielding to ground it didn't have any impact on the hum.
Image of footswitch and reverb tank connection to board:
https://firebasestorage.googleapis.c...2-9484293a158f
Full schematic:
https://www.drtube.com/schematics/ampeg/g12-jp.gif
Here's how it behaves:
-Reverb pot directly affects hum volume, 0 = no hum, 10 = lots of hum
-Disconnecting reverb tank eliminates hum
-Removing V7 eliminates hum
-Toggling footswitch does NOT affect hum
-Removing V6 does NOT affect hum
One thing I noticed is that the schematic appears to show a ground lead from both sides of the reverb tank. One of the leads from my reverb tank has the shielding wired to ground, but on the other one the shielding is just trimmed off. There appears to be a through hole to ground adjacent to the reverb signal line that was never soldered? However, when I tried running a jumper from the cable shielding to ground it didn't have any impact on the hum.
Image of footswitch and reverb tank connection to board:
https://firebasestorage.googleapis.c...2-9484293a158f
Full schematic:
https://www.drtube.com/schematics/ampeg/g12-jp.gif
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