The Amp Garage

Thanks for your reply. The 220k resistor in question is the grid leak resistor on V3a, the reverb recovery tube. If your starting to burn up that 3 watt 1k resistor that is 2 power supply dropping resistors away from the reverb circuit and in that case you have a output stage short going on, because...

I have a PR build here experiencing a difficult birth. Once built I powered up with light bulb limiter, all seemed fine to proceed, voltages checked out, bias voltage present. Installed tubes. Hooked up my bias probe but put this on the GZ34 tube. When I realised this I powered down and continued w...

I don't see anything wrong. Maybe there was a whisker wire that burnt up. The diodes can be on pin 1 or straight to ground as long as pins 1-8 are tied together then to ground. The blue Center Tap wire of the OT is going to the standby switch yes? Mark Yes, blue CT to standby. I’ve got the replacem...

Mark, thanks for this, caution is better, particularly given this is my first EL34 amp.

Phil that’s great info, very reassuring!

Thanks Phil, that makes sense. Secondaries are reading less than an ohm apart when measuring to common. Can I ask if the difference in plate volts and minor difference in resistance in the windings are of concern. I’ll fire ahead with replacing the tube socket and bias to the tube with the higher pl...

I can’t seem to dig the OP transformer wiring diagram up. The secondaries and octals were wired earlyish in the build, using the paper diagram supplied. I mailed RJ last week to verify the primary wiring, particularly the CT. Meantime, and prior to firing it up I found this http://i288.photobucket.c...

Thanks Sluckey

Yes, doesn’t look good in the pic.

The flyback diodes seem to have done their job.

I was doing initial setup and bias with no guitar plugged in and with the amp connected to a Suhr reactive load.

That joint will be fixed once I get the new socket in.

Having done a little reading on arcing my current (forgive the pun) is dust becoming conductive. The arcing was between pins 3 and 2. The build got pretty dusty in between bursts of build activity. I cleaned up the boards and chassis with a special hoover attachment but neglected to clean the socket...

Thanks Phil, I’ll use the 1ohm resistor as the sole ground reference then. Tubes were definitely not red plating. I’ve ordered a couple of tube sockets. Will try again Thursday. Yeah I’ve never seen anything like it, closest I can describe it is that it was like a sparkler in the tube socket, no smo...

Thanks Phil Ok, I’ve jumpered pin 1 to ground and have removed the jumper from pin 8 to ground for the time being. If there’s no detriment to the amp in leaving in the 1ohm resistor to ground I’ll do that. I can’t tell myself what the cause was. The 5 watt resistor tests fine out of circuit. Here’s ...

Hey guys First of all I’d like to say a big thanks to the forum for all the knowledge that’s been shared here that has allowed me to build an Express. Particular thanks to RJ who provided me with the kit to built it. It’s taken a while but is finally built. I followed the lamp limiter/start up proce...

I have had a desire to build a Deluxe Reverb for a long time now. As I'm planning to do this as a scratch build I'm wondering if I can add another tube and mod the normal channel to have a Trainwreck style preamp (extra triode would be the cold clipper stage) I'd ideally like to leave the vibrato ch...

Phil, thanks loads, that makes more sense. Ordered.

Best

Jim

I’m looking for a UK spec MOV and am really just guessing at the specs.

Is anyone with more knowledge than I willing to say if this is a suitable UK part?

https://uk.rs-online.com/mobile/p/metal ... s/8518316/

Thanks Rooster that’s very useful!
I may pull the PT from the chassis and test in this fashion to be sure.