Tremolux 5G9 - tremolo not working

[haricros]

Hey all,
I'm working on a 5G9 Tremolux right now. All of the voltages are perfect with a 5Y3 rectifier (much higher with the 5U4 it calls for). It sounds great - it's just that the tremolo isn't working at all. When I turn up the intensity, it just bumps the gain up. The speed has no effect whatsoever. Just wondering if anyone has any suggestions. Thanks in advance!!

[tubeswell]

Sounds, from your brief description, like wiring errors.

What are the (plate, grid cathode) idle voltages on the LFO stage and associated CF stage?

[haricros]

Tubeswell,
Thanks for your response. Not sure what your acronyms stand for, but here are the voltages on all tubes:
V1 (Pre) - (1) 167v (2) 0.06 mv (3) 2.5v (6) 161.3v (7) 0.06 mv (8) 2.5v

V2 (PI) - (1) 217v (2) 15.8v (3) 24.5v (6) 201v (7) 16.8v (8) 24.5v

V3 (Trem) - (1) 255v (2) 3.6mv (3) 1.75v (6) 369v (7) 255v (8) 257v

6v6 (both) - (3) 375 (4) 376 (5) -27v (6) 377v

Thanks for your time. The only other issue seems to be that the voltage seems to fluctuate a bit - as much as 10 to 15 volts. When I turn the trem circuit on, it there is a significant drop, which I would expect.

[tubeswell]

So is the coupling cap from the CF (cathode follower) stage of the trem circuit going through the voltage divider that is the 1M-250k pot, and is the wiper of the depth pot going to the bottom of the 2 x 220k grid load resistors for the 6V6s?

[haricros]

Yes and yes. Just as the schematic. Pin 8 from the 12ax7 to a .1 orange drop, to a 1M resistor to the right hand lug of the 250k depth pot. The middle lug of that pot is connected to the middle of the 2 220k resistors. I've added a couple of 1.5k resistors between the 220k's and pin 5 of the 6v6 tubes. Would this be the problem?

[tubeswell]

Then you must have something miswired/not working in the oscillator (LFO) section. Since the voltages on the LFO triode appear okay, maybe check around the RC network for leaky caps or mis-wiring.

The 1k5 grid stoppers shouldn't affect the operation of the bias-wiggle.

[haricros]

I changed out all caps in the trem section. The pots and resistors are all reading as they should.

I have a 10k Pot in the bias section. It runs as such: Rectifier Pin 4 - 100k resistor - diode - right lug of bias pot. Centre is tied to a 50/50 Cap (tied to ground) and the left lug of the 250k Intensity pot. The left lug has a 22k resistor tied to ground.

The only other thing I haven't done is tie 100ohm resistors from the heaters to ground.

Otherwise, I've been through the circuit a zillion times. Any suggestions?

[tubeswell]

Something is definitely miswired. If the LFO is hooked up properly, it will oscillate. Go back and quadruple-check the layout with your R meter. And have a copy of the 5G9 schematic and layout handy as you go, so that you can tick off each wire.

[pontiacpete]

you probably have already done this, but have you tried shorting the trem footsw jack with a clip lead?

[tubeswell]

you probably have already done this, but have you tried shorting the trem footsw jack with a clip lead?

Shorting the trem footswitch jack in a 5G9 circuit actually turns the trem off (by grounding the middle of the LFO RC network).

[haricros]

AT LAST!!! It's up and running! I was killing myself over the trem circuit itself, and all that was wrong was the resister on the speed pot wasn't as solid as it should have been. Now, I am hypnotized. Great trem. Pretty impressive. Thanks for your help, Tubeswell and Pontiac Pete. The Tremolux is truly a hidden gem amongst the Tweed circuits - perhaps because it's so close to the brown Deluxe, though better tremolo for sure.

[tubeswell]

AT LAST!!! It's up and running!... Now, I am hypnotized. Great trem. Pretty impressive. ... The Tremolux is truly a hidden gem amongst the Tweed circuits - perhaps because it's so close to the brown Deluxe, though better tremolo for sure.

That's what I been sayin' since I built mine, and its still my #1 gigging amp at the local blues club jam nights. That slam is mesmerising.