I maintenance a JMP 2203 from the 70's for a friend and I have a weird issue that I can't point on.
What I changed :
- 6 Filters Caps
- 2x 10uf Bias
- Add 4 1ohm resistors on power socket
- Relocate the 4ohm NFB to 8ohm
- Relocate the 68k and the Preamp middle pin directly to the V1 socket
- Replace all the pots
- Remove the 100pf added on the V1 probably because of the NFB on 4ohms.
Everything works good, all current seems good too.
The weird issue is : It sound perfectly, but the Master act like the Volume I of a SLP and the preamp pot doesn't work at all.
I tried 3 pots, another set of tubes, checks the schematic and the replica I made. I can't point the issue. So if you have an idea, please
