Solid State Guitar Amp Forum | DIY Guitar Amplifiers

This might help:

https://www.tubesandmore.com/products/jacks_plugs

All the best,
Will P.

Has anyone traced out the Ultimatum Distortion Generator?

Do u have the schematic?

I haven’t contacted GK yet, but thought I’d ask here first — looking for the schematic for this GK footswitch used on the 112SC, 212SC, 150GT, etc from ~1980. The PCB inside is marked 50033B. The unit I received was DOA and someone disconnected the leads to the B channel switch at some point. I have a 112SC to test with.
 

Thanks for your posts! - this is a great forum (I’m relatively new) and a wealth of information here.

Well technically not a solid state guitar amp schematic, I figured I would try here to track down schematics by the Studio Supply Company. These two cards came from a distribution amplifier out of a concert hall built in 1974. I believe the distribution amplifier fed individual offices in the bottom of the concert hall. I am trying to track down the schematic for what appears to be a multi band graphic EQ, all discrete which is in the second image. The first image is the backside of the only card that actually shows the logo of the company. Any help would be appreciated as always. Thanks.

Honestly, if you haven’t used the scope in a while then I would be weary of poking around the output section of a power amp without some guidance. The scope probe has a ground ring and can easily short stuff and damage your amp if you don’t have the protective sleeve (condom) for it. Or if the alligator clip snaps off and drags across the PCB. I’ve done it - not fun. 

To test the power amp alone, you’ll need to run a sinusoid through it via the fx return. Do you have a dummy load to connect to the output of the amp? Then you can run a signal into that rather than the speaker and look with the scope hooked across the dummy load. That will keep you out of the amp chassis and is safer. You can also probe the output jack (speaker leads - be careful) with no load connected, but my old boss (guru) always made us test for that with a dummy load. With the speaker itself you are going to get a noisy signal and the crossover distortion “glitches” do not necessarily occur in the center of the waveform, so might be hard to see, or obscured. Be really careful and get a dummy load if you can.