Super reverb build, vibrato doesn’t work

[Bob-I]

Hi folks. I re-built a Super Reverb using a PCB from AA Electronics out of the UK. Originally this was a 20 year old (maybe) Weber kit and some off the components were questionable quality. I decided that instead of using the original board and replace all the components, I’d try this PCB. FWIW the board is very good quality and makes for an easy build, the amp sounds great and is very quiet.

However the vibrato/trem doesn’t work. I double checked all the component values, metered them, and replaced the roach and tube with known good parts. The light is on, but dim and doesn’t modulate, turning up the intensity reduces volume.

The only thing I can find wrong is the cathode on V5B is only showing 4.7v where it should be 17v, and the plate is high, most likely because off the low cathode voltage. The cathode resistor measures 99k.

Any troubleshooting help is appreciated.

[sluckey]

That circuit requires a footswitch to enable the tremolo. Connect a footswitch or put a shorting plug in the VIB footswitch jack. Any joy?

[Bob-I]

That circuit requires a footswitch to enable the tremolo. Connect a footswitch or put a shorting plug in the VIB footswitch jack. Any joy?

Yes, I shorted the Jack with a jumper and the light comes on.

[Bob-I]

Well scratch this…I shouldn’t just read the component value and measure it, I should check the schematic to make sure I have the right value first, had a .01 where a .02 was called for.

That said, the trem worked but was very fast, unusable fast. I upped the ,02uF to .047 uF then.1 uF to get it under control. That might have been overkill, but it’s giving me a really swampy slow trem, kinda cool, and the range is just fine, goes up to “Crimson and Clover” speed just fine.

I’m gonna clean the board up, and put it back in the cab ready for this weekend’s gig.