Whats the cause of volume cut out?

[Dandrix]

What causes volume to cut out? i am testing my controls out on the vibrato side of my Super Reverb(ab763) and noticed that the volume turned up to nine and treble turn up to seven and mids at seven, the volume cuts out and there is a thud or pop. the other example would be mid on 10, treble at 10 and work the volume up north of seven it cuts out again. vibrato channel wired to schematic. Normal channel functions properly, no volume cut.

[xtian]

There are many possible causes. Dirty pots, dirty tube pins, broken and intermittent solder connection, alien abduction, to name a few...

[pdf64]

Are you asking about the mojo kit build that had this issue years ago, or is this a vintage Fender?
Has it ever worked right?

[Dandrix]

yes, it is a mojo kit.

[Dandrix]

i have touched up solder joints on all vibrato pots and tone stack section. the volume pot would be my first choice for replacement?

[pdf64]

The possibility was raised the your previous thread on a Mojo SR build of the issue being due to oscillation; have you eliminated that as being the cause?
eg in the fault mode are there any changes in Vdc along the preamp cathodes, does the 6L6 cathode current change?

[Dandrix]

Pdf64,
Would you please refresh my memory on the:
“The possibility was raised the your previous thread on a Mojo SR build of the issue being due to oscillation; have you eliminated that as being the cause?“
Don’t recall that issue? Just wanted to refresh my memory. Ty

[Dandrix]

Pdf64,
Would you please refresh my memory on the:
“The possibility was raised the your previous thread on a Mojo SR build of the issue being due to oscillation; have you eliminated that as being the cause?“
Don’t recall that issue? Just wanted to refresh my memory. Ty

I found the thread from 2013, sorry.
No, I have have not grounded the input jacks with shielded wire. I will do this, I really never turn my amp over four on the volume. I am currently rehousing the chassis in a head unit cabinet and fixing some things I have done wrong. I knew nothing about grounding schemes then.
A lot goes into these amps even at the simplest level. I will get back to you if that was the fix.

[Dandrix]

That’s the fix. Input jack now grounded to pre amp ground. All pots hit ten now without cutting out.
The post from 2013 was another build I was working on. That why I was confused. All good, ty