bassmanfox
New member
- Joined
- Feb 4, 2009
- Messages
- 3
Hey All,
So I've never posted here, but have lurked for years and always love what goes on. Anyway I wanted to first pre-thank yall for help.
I've been fixing tube and solid state electronics professionally for about 15years and tinkering for 20+. The other day I had a friend bring a me a federal limiter that basically needed a full restore.
I've replace all the caps. (film and electrolytic)
Replace the out of spec resistors. (I haven't taken all the resistors of circuit to be 1000% but the ones that are in here read within 10%)
Replaced the rectifier tube(it was bad) with diodes, added some extra filter caps/resistors and removed the Inductor(choke) from the circuit. This was noted in another post here, so I figured it was worth a try and it did help hum.
Put a matched pair of NOS 6sk7's in there.
Now I still have a problem, depending on where the current is set or how much attenuation is going on, once I turn up the threshold all the way(clockwise) it motorboats. It motorboats in bypass mode as well and if I remove the 6sq7 it goes away. I've swapped the 6sq7 and the 6sn7 with what seem to be working tubes(its possible they are not, but the all seem to function exactly the same).
First off I've never worked or used one of these before, so I'm just not certain if that"normal" More specifically if the current control meant to function across the whole turn, because if the current is set to spec, I don't necessarily get motorboating
Second if motorboating should never happen, no matter where current and threshold are, then does anyone have any troubleshooting advice?
I think next I'll read the impedance of the transformers, but was hoping for some insight first
Much love....
So I've never posted here, but have lurked for years and always love what goes on. Anyway I wanted to first pre-thank yall for help.
I've been fixing tube and solid state electronics professionally for about 15years and tinkering for 20+. The other day I had a friend bring a me a federal limiter that basically needed a full restore.
I've replace all the caps. (film and electrolytic)
Replace the out of spec resistors. (I haven't taken all the resistors of circuit to be 1000% but the ones that are in here read within 10%)
Replaced the rectifier tube(it was bad) with diodes, added some extra filter caps/resistors and removed the Inductor(choke) from the circuit. This was noted in another post here, so I figured it was worth a try and it did help hum.
Put a matched pair of NOS 6sk7's in there.
Now I still have a problem, depending on where the current is set or how much attenuation is going on, once I turn up the threshold all the way(clockwise) it motorboats. It motorboats in bypass mode as well and if I remove the 6sq7 it goes away. I've swapped the 6sq7 and the 6sn7 with what seem to be working tubes(its possible they are not, but the all seem to function exactly the same).
First off I've never worked or used one of these before, so I'm just not certain if that"normal" More specifically if the current control meant to function across the whole turn, because if the current is set to spec, I don't necessarily get motorboating
Second if motorboating should never happen, no matter where current and threshold are, then does anyone have any troubleshooting advice?
I think next I'll read the impedance of the transformers, but was hoping for some insight first
Much love....
