I've got an SLP on the bench that is very quiet. When I crank it the loudness sounds to be about 10W even though it brakes up as if it was at full volume. The voltages seem to be fine and I've tried new tubes and different cabs but the issue remains. If anyone could help me solve this puzzle I'd appreciate it. I'll post my voltage readings tomorrow.
Thanks
Super Lead Plexi 100 RI is extremely quiet.
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chris_d
- Solder Soldier
I had an amp do this when the OT blew. I pulled the OT, and IIRC, the primary did not measure as expected from lead to lead. However it shorted, it did not disable the transformer completely, just turned it into sort of an attenuator. The distortion sound was actually very good, just super super quiet.
I don't know what else could cause that behaviour, but that is what it was for me. In my case i had an arcing power tube socket that was causing trouble. Make sure to check all of your sockets for evidence of arcs, burning, etc. It was hard to see on my amp due to the dark color phenolic sockets i used, but it was there.
A RI Marshall probably has a quick connector for the OT? It might be easy enough to pull it out and test it for shorts.
-chris
I don't know what else could cause that behaviour, but that is what it was for me. In my case i had an arcing power tube socket that was causing trouble. Make sure to check all of your sockets for evidence of arcs, burning, etc. It was hard to see on my amp due to the dark color phenolic sockets i used, but it was there.
A RI Marshall probably has a quick connector for the OT? It might be easy enough to pull it out and test it for shorts.
-chris
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soulsonic
- Old Solderhand
Information
Oh, thanks for mentioning that Chris! I'm working on a Traynor right now that has similar symptoms and now I know I should definitely check the output transformer. Yikes!
"Analog electronics in music is dead. Analog effects pedal design is a dead art." - Fran
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soulsonic
- Old Solderhand
Information
OH NO! I tested the output transformer and it is indeed dead!
Here's the readings I got:
Secondary DC Resistance: 1/2 ohm (!)
Secondary Inductance: 47mH (!!)
And, to top it off, I measured a resistance of about 100K (!!!) between Primary and Secondary coils.
I did all these measurements with the secondary completely disconnected from the jacks and the rest of the amp; and the measurements of the primary were done with the transient voltage suppressor diode lifted so it wouldn't interfere with any DC readings.
I might run some AC voltage through it later, just to be sure, but I'm convinced that this poor thing is now a paperweight.
Here's the readings I got:
Secondary DC Resistance: 1/2 ohm (!)
Secondary Inductance: 47mH (!!)
And, to top it off, I measured a resistance of about 100K (!!!) between Primary and Secondary coils.
I did all these measurements with the secondary completely disconnected from the jacks and the rest of the amp; and the measurements of the primary were done with the transient voltage suppressor diode lifted so it wouldn't interfere with any DC readings.
I might run some AC voltage through it later, just to be sure, but I'm convinced that this poor thing is now a paperweight.
"Analog electronics in music is dead. Analog effects pedal design is a dead art." - Fran
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soulsonic
- Old Solderhand
Information
Yes, I read that article last night before I started testing; just to make sure I knew what I was doing and wasn't forgetting any details. 
"Analog electronics in music is dead. Analog effects pedal design is a dead art." - Fran