Fender Dual Showman Reverb with safety issues

[aiyiadam]

I recently came across this article that discussed relocating a ground wire makes a huge difference in the ticking. I haven't had one in recently to try, but might be something to consider. See towards the bottom of this article.
https://www.effectrode.com/knowledge...-with-tremolo/

Thank you for the link. The suggested grounding makes a lot of sense.. However, I have tried it and it didn't change much.

[aiyiadam]

Yesterday I have experimented with some led's until I have broken the photoresistor leads. I will need to wait a couple of days for new photo resistors. Leds sound better to me. There is still this coupling between the reverb and the vibrato even when I take the roach out. I hear the swooshing sound of the vibrato if the reverb is on. Since the reverb and the vibrato tube plates have a common DC supply, can this be inherent to the design?

I've never ever seen a reverb tank like that. Unless someone else has, I would say it is definitely not the stock part, so would not spend any time on it.
There is a wire that goes right up against the opto-coupler. If you did not try moving it when you played with lead dress, give it a try. I've had success with it reducing ticking sometimes.

Yes.. I will need a new reverb tank. In my case this wire between the optocoupler and the sixth pin doesn't seem to cause a lot of noise. The wire connected to the V5 grid is troublesome. I have used shielded cable and tucked it under the 22nf cap.

[g1]

There is still this coupling between the reverb and the vibrato even when I take the roach out. I hear the swooshing sound of the vibrato if the reverb is on.

Is this with no footswitch connected?

[aiyiadam]

Is this with no footswitch connected?

I hear it, when the vibrato is turned on with a shorted plug. The noise is there even when there is no signal input.

[g1]

Since the reverb and the vibrato tube plates have a common DC supply, can this be inherent to the design?

You did not mention if you had replaced the filter caps. It is not inherent in the design but bad filter caps might allow the trem oscillator to modulate the supply node.

[aiyiadam]

You did not mention if you had replaced the filter caps. It is not inherent in the design but bad filter caps might allow the trem oscillator to modulate the supply node.

I have new F+T filter caps and I don't think that I have a bad cap. Other than the vibrato the amp sounds okay...

I experimented with various groundings in the dog house ( this silverface Fender had four different ground connections there), I moved the supply node of the reverb between the 1K and 4K7 resistors, tried other tubes. And I still have the vibrato beats coming from the reverb.

[aiyiadam]

I think I know the problem now..The grounding cable coming from the tube cathode was probably carrying signal between gain stages. I didn't solder it to any filter cap, but I was keeping the loose end in the doghouse for a bit of tidiness. Laying those grounding cables "over" the tube socket cables is probably also not a good idea..

Without this grounding cable there is still a bit of swooshing noise, but it should be acceptable..

The roach.. I have experimented a bit with leds and decided to stick to neon. In higher speed settings my leds don't react fast enough and the the intensity decreases too much. Neon functions here better. So.. Grabbed a green neon and a 10mm photo resistor and put them in a heat shrink. It will do for now.

Now the power switch has started to be problematic. I will try to open and clean it..