Post by rodr on May 2, 2019 17:20:47 GMT -7
I've been a lurker for a while, and just recently got my second Z! I've used a Route 66 for a while and I really really love that amp. I Just got a real good deal on a really nice condition Galaxie + red Z best cab. Couldn't pass! Everything is in really good shape. Both channels sound amazing, and it's a monster volume wise.
BUT... it does have some hum. It's certainly more noticeable than in my Route 66 (which has a little hum but nothing out of the ordinary), and I tried the cab with my ampeg GVT15H, and that's dead quite. I tried other combos in the same outlet and none has Hum this noticeable.
When playing, the hum is masked and I got beatiful tones, but as soon as I stop playing, it's noticeable. The amp hums with volume all the way down, and with nothing plugged in. As soon as the standby switch is flicked to ON, the hum comes up. If it's any clue, the channel indicator LED is not completely OFF when in clean channel, you can see a dim light.
So far I tried:
-Other amps with same cables and cab. No hum.
-Replacing pre amp tubes one at a time with known good one.
-Replacing both power tubes with known good ones.
-Replacing the rectifier (EHX) with NOS GE.
-Different speaker cable.
No luck so far. I think I could live with the hum in a real live situation, but for recording it might not be acceptable. So I come here for your expertise and advice!
Shipping the amp to the good Doctor it's cost prohibitive, since I am outside the US.
I have electronics experience and have rebuilt/restored/maintained my own and friend's amps. Cap jobs, three prong conversion, etc.
I know it could be a bad filter cap, that would take me a while to source good material to replace it.
Finally, I took some pics inside the chassis (which looks immaculate with impeccable workmanship) and a video showing the issue, if it's any help. First the family pic!:
Now the guts:
And the vid (hum better heard with headphones):