Vox AC15 TBX: input 1 problem

[Sea Chief]

Hi- odd things happening at my inputs 1 & 2. A few days ago getting very loud 'earthy' buzz noise plugging into 1, shoving the lead about sorted it but precariously 'at any moment' about to go BUZZ!! on me if I shifted it.

Today, I plug into 1 but get nothing but the loud buzz/ no gtr, nothing. Oddly input 2 seems ok, but, its way louder than before: with input vol at 10 (my usual goto setting) I can barely touch the MV on at all & its way louder than when both inputs were working ok.

It seems to me there's some sort of interaction between the two that's not functioning with no.1 out of action. Would that be right?

thanks- SC

[Sea Chief]

The schematic is in #2 of this thread (thx Dave H)

https://music-electronics-forum.com/...light=vox+ac15

[alexradium]

not much mistery,jacks go bad,oxidation first problem,or bad solderings both on the jack or the ground reference

[pdf64]

Yes, from your report it seems likely the connection between the amp's 0V circuit common and the sleeve of the #1 jack has failed somewhere, shouldn't be too hard to identify where that's happened and resolve it.
As previously mentioned repeatedly, my experience is that these amps benefit from their pcb solder joints being reflowed, so maybe it's just a bad joint on the jack?
To save trawling through the linked thread here's the schematic https://el34world.com/charts/Schemat...x_ac1596pr.pdf

[Sea Chief]

not much mistery,jacks go bad,oxidation first problem,or bad solderings both on the jack or the ground reference

Actually your post inspired me to clean really well/ best I could.. & fingers x'd its done the trick!

seems the two inputs are interactive to a degree, ie one n/g makes other one go on steroids.

thanks- my shortest thread I think. SC

[pdf64]

...seems the two inputs are interactive to a degree, ie one n/g makes other one go on steroids...

It shouldn't work like that, there is no attenuation of the #1 jack.
Plug an open lead into it, and (measuring from the plug at the other end of the lead) there should be 1M between tip and sleeve, and 34k between tip and terminal 2 V5 (input stage grid).