vox ac4 tremolo/vibrato not working

[Kesi from Hungary]

Since I recently have the possibility to make eyelet boards myself, I decided to rebuild my vox ac4 from an earlier project.
The starting point was the ac4 design by dwinstonwood with the Fender vibrato. That appealed to me very much.
The amplifier sounds very good, but there is no tremolo effect. I did measure a pulse in changing voltage.
I have checked the wiring many times. At first I had everything neatly under the board, but when checking I temporarily moved it up.
So the big question is whether this is due to the voltages on the vibrato or is my wiring too long and are my potentiometers too far away, or crossing wires?
When the vibrato works, I want to run the wiring under the board again and clean things up.
Hope that someone  can help me correct my mistake or error.

Rectifier solid state

Voltages
A: 286V
B: 279V
C: 271V

el84
7. 271V
9. 276V
3. 8.03

ef86
6. 273V
1. 28.60V
3+8. 0,5V

12ax7
6. 273V
1. 172V
3. 1,6V
8. 178V

[Lectroid]

Perhaps a dumb question, but have you checked the footswitch circuit? 

"Reverb will work without the FS, but Tremolo requires a FS to be wired to the board in order to function."
https://el34world.com/Forum/index.php?topic=32263.msg358598#msg358598

A reverb circuit turns "off" by grounding the reverb signal, so no signal gets through to the recovery tube.   A tremolo circuit is turned off by breaking the ground to it. 

[kagliostro]

BTW, this is Dwinstonwood version of the schematic with voltages (if you want to compare it to yours)

https://el34world.com/Forum/index.php?action=dlattach;topic=27253.0;attach=91399

Franco


Oh, I see, you have a newer version of the draw

[tubeswell]

If the LFO is pulsing, but there is no tremolo getting through to the signal path, then the problem must be in the CF or between the CF and the cathode of V1. Triple check your wiring around those parts with an R-meter (to check for DC-continuity)

[HotBluePlates]

Perhaps a dumb question, but have you checked the footswitch circuit? 

"Reverb will work without the FS, but Tremolo requires a FS to be wired to the board in order to function."
https://el34world.com/Forum/index.php?topic=32263.msg358598#msg358598

You linked a different amp, different circuit, different result from having/not-having the footswitch.

Kesi's plan has the oscillator always running, unless the footswtich is activated to kill the LFO signal by grounding it at one of the R-C stages.

... there is no tremolo effect. ...
I have checked the wiring many times.

Maybe I'm seeing it wrong, but:

You have a Gray Wire to Pin 2 from one of the R-C capacitors for the oscillator.
However, the Orange Wire from the other end of this R-C string goes to Pin 7 (the other tube section).  It should be connected to Pin 1, and a short piece of wire from Pin 1 to Pin 7.

   - In a pinch, you could tack a short wire from Pin 7 to Pin 1, which should have the same electrical effect.

I think your oscillator doesn't run because the R-C sections do not run from Plate (Pin 1) to Grid (Pin 2) of a single triode section.

[Kesi from Hungary]

Sorry 'HotBluePlates' that my picture was not clear. This one is made from another direction 1 and 7 are connected with a copper colored wire.

... there is no tremolo effect. ...
I have checked the wiring many times.

Maybe I'm seeing it wrong, but:

You have a Gray Wire to Pin 2 from one of the R-C capacitors for the oscillator.
However, the Orange Wire from the other end of this R-C string goes to Pin 7 (the other tube section).  It should be connected to Pin 1, and a short piece of wire from Pin 1 to Pin 7.

   - In a pinch, you could tack a short wire from Pin 7 to Pin 1, which should have the same electrical effect.

I think your oscillator doesn't run because the R-C sections do not run from Plate (Pin 1) to Grid (Pin 2) of a single triode section.

[Kesi from Hungary]

If the LFO is pulsing, but there is no tremolo getting through to the signal path, then the problem must be in the CF or between the CF and the cathode of V1. Triple check your wiring around those parts with an R-meter (to check for DC-continuity)

Tubeswell , still learning here so I go back to reading about cathode followers.
I'm bad at theoretical visualization so finding CF

[HotBluePlates]

... still learning here so I go back to reading about cathode followers.
I'm bad at theoretical visualization so finding CF

Pins 6, 7 and 8 of the socket you re-photographed for me.

[Kesi from Hungary]

Pins 6, 7 and 8 of the socket you re-photographed for me.

measured from cathode V1 to
pin 6 continuity
pin 7 continuity
pin 8 no continuity

[Lectroid]

Perhaps a dumb question, but have you checked the footswitch circuit?

 
You linked a different amp, different circuit, different result from having/not-having the footswitch.

I was right about one thing--it was a dumb question.   

[dwinstonwood]

Kesi, I just saw this thread. If it helps, here are my latest/final drawings. I rebuilt this amp a few times until I finally got the Tremolo to work. After I returned to the original Vox AC4 V-1-1 schematic values for the EF86, the Tremolo worked great.

[dwinstonwood]

I just pulled out this amp and did a complete re-tube for fun: Made in Holland EL84, NOS Tesla EF86, ANOS short black-plate 12AX7, and a Tesla EZ81. Both the Speed and Intensity controls work great and have a very wide range. The old tubes I just put in sound very good.

Maybe it sounds good because I was playing my "over-the-top" Custom bound-body Sherwood Green Tele with a tortoise shell pick guard and Bootstrap early 60's pickups. It's either an eyesore or you love it. No middle ground.

[Willabe]

Bootstrap early 60's pickups.

What are bootstrap PUP's?

[jojokeo]

Sherwood Green Tele with a tortoise shell pick guard - It's either an eyesore or you love it. No middle ground.

Eyesore for me lol    I think a mint green would look sharp and breakup all the dark colors

[Kesi from Hungary]

Bootstrap early 60's pickups.

What are bootstrap PUP's?

https://bootstrappickups.com/

[Kesi from Hungary]

Kesi, I just saw this thread. If it helps, here are my latest/final drawings. I rebuilt this amp a few times until I finally got the Tremolo to work. After I returned to the original Vox AC4 V-1-1 schematic values for the EF86, the Tremolo worked great.

thanks dwinstonwood, I had your latest version as a starting point for the build. But I did go back to earlier schematics of your build, when the vibrato did not work to look at the value of the resistors from C area. I tried different values. Unfortunately without result. By replacing the 10K to 22K I came pretty close to your voltages. Only the screen grid on V1 lags behind a bit.

[dwinstonwood]

...I think a mint green would look sharp and breakup all the dark colors

I originally had a mint guard on it. I've been switching colors until I find what I like best. And the mint green is better that the tortoise shell.