MY one and only ORANGE Super Bass JMP 100 Mk 2

Ok Chili-Willy...

Maybe the trip home after you bought the amp might have amplified an inherent weakness or defect in a tube, or tubes. Or... loosened some shoddy soldering work since we know the amp has been questionably molested.

You have to make sure what condition all those tubes are in. You need to find a source for tube testing.

That speaker impedance switch circuit needs to be rebuilt properly. This is a must!

Check for any signs of arcing at the power tube sockets. In between the pin sockets on the tube side of the sockets. This might be why V5 was worked on. Looks like the grid and screen resistors were replaced at V5. I can't tell if the socket itself was changed, but if it arced before, it could be cracked and damaged and needs to be replaced.

Doing your best that the wiring checks out, you can then actually check the voltages of all the pins of all the tube sockets WITHOUT any tubes installed. You don't have to have a speaker load hooked up. You'll need to be plugged into a speaker load only when the power tubes are installed. Just remember that the pins for the Heaters are going to be AC, and the rest will be DC. When I get to my PC later, I'll post a voltage chart as a guide for that Super Bass.

The impedance switch and a tubeless voltage chart is where I would start first. Because if any of the voltages are way out of spec, this could be traced to a singular culprit. Let's hope that the trannies are all good.
 
Mr Grumpy said:
That is a very cool amp although it looks a bit psychotic, if not a total psychopath...

Surely, every guitar player would want one of these.

Does it sound like this one:

Click to expand...
Damn I bet that sounds so good in person!
 
Voltage chart as promised...
Pexi 100 watt voltage chart.png


That chart came from Metropoulos Amplification, from the days when they used to sell Marshall clone amp kits.
 
If those Ruby's sound anything like the set I had from the early 90's, don't ever lose them!

This amp has potential, even if it is less than perfect right now.

Burke Hunn is out near Dulles Airport. He can restore it, if you wish to go that route.

Main <-Hunn Amplification site.
 
Cool deal, Mdub. I also just emailed Jeff Bober, Budda/East amps to see if he will check my tubes for me and if needed, other service work.
 
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