Super Reverb trem intensity acting as master volume?

vanguard

Member
Messages
2,515
So I have a 1963 SR. The trem didn't work when I got it; the speed and intensity knobs did nothing. When I opened the amp up I could see the neon flash when I first turned on the trem, then it would go dead. I assumed this meant a new "bug" was the ticket so I bought an nos neon bulb and an LDR and made a new bug. After installing I can see the light flashing and hear the faint ticking, but no tremolo occurs and, as I turn the intensity up, the master volume goes down until total silence. I've checked trem tube, of course. Any ideas?
 

zenas

Member
Messages
8,871
Did the intensity knob act like that before ? Terms are pretty simple on those. Two electrolytic cathode bypass caps that should be changed already, then a few resisters, those three ceramic caps, two pots the bug and a tube. Switch or shorting jack makes it work.
Looking at the schematic I'd say the pots wired wrong or the bug has the wrong resister. Somethings grounding signal.
Of course I've been wrong before. . .
 

pdf64

Member
Messages
8,914
Is the LDR the correct replacement?
Have you wrapped the optocoupler assembly in a optically opaque material? eg black tape, heatshrink.
If the LDR is able to detect any light source other than the neon, its resistance will stay low and the trem intensity control will operate in the way described.
 

vanguard

Member
Messages
2,515
Okay, got it working. I reflowed a couple suspect looking solder joints in the circuit, and taped off the slightly open ends of the shrink wrap in the trem bug. Sounds amazing now with zero clicking!

Thanks for the the advice!
 




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