Baldwin C1 input jack socket query

[rogerandout]

Hi all, I have one of these amps in for service and noticed that on input 1 jack socket on both channels, that the 'ring' is connected to the PSU and has about 33V on it - what's the idea?

many thanks

[Loudthud]

Some amps use a scheme like this to detect when something is plugged in to mute the channel when nothing is plugged in. On this amp, it looks like they are providing power to some kind of active guitar or perhaps an accordion.  A normal phone plug will short it to ground, but it will send a jolt to your guitar if you plug in while the amp is on. Probably a good idea to disconnect it.

[rogerandout]

Thanks for the reply, yes I wondered if it was as you suggest, cant be a good idea putting 33V into you 59' Burst PAFs 

I have disconnected it