Vox Escort 50 Lead - high input not working, mysterious cut wire

[meathane]

Hey everyone,

Hope it's ok me registering to request some help. I recently purchased an Escort 50 Lead that has a few issues. I get volume jumps that frighten the life out of me ha, but after some pot cleaning, and leaving it on for 5 mins before using it, it seems better.

But aside from that, I get no noise from the High input - not a trickle, scratch nothing. Low input works. I've sprayed contact cleaner in the jack, and checked the solder joints, which seem fine. On the bottom of the circuit board, I can see a wire that's been cut (it probes to ground, which all posts on the jacks do anyway, so no surprise there). The wire is soldered to the first leg of the 470n/160V cap, and seeing as this cap is the first component after the High input jack, my suspicions are it's something to do with this.

I've found a hand drawn schematic for the amp, but I just don't know enough about schematics to understand what I'm looking at I'm afraid. I'll attach some pictures. Maybe this was a mod a long time ago, and rather than desolder it to remove the mod, somebody just cut it instead of removing the board and desoldering properly ? Here's the link to the schematic from this site https://music-electronics-forum.com/...etch?id=854117 but any help would be amazing, the amp's in great condition, I guess I want to love it

[Jazz P Bass]

If you have signal at the jack, then it should also be at the 470n capacitor.
If so, do you have signal on the other side of the capacitor?
Does the signal make it to the opamp? (pin 1)
Does it come out of the opamp? (pin 3)
Does the 1M potentiometer work correctly?

[g1]

Can you post more pics of the jacks themselves as they are currently wired. (edit: show where the black wire from High jack is going)

[Jon Snell]

I suspect, as someone has been playng in there,(unskilled personell I call it), it would be a good idea to take the board out of the chassis and take a closer look.
In the meantime, I would wire up the sockets correctly.
Heres the schematic of the input sockets;
There is only ONE resistor your photo shows two.

[g1]

Heres the schematic of the input sockets;
There is only ONE resistor your photo shows two.

That schematic is for the Escort Bass 50, this is an Escort Lead 50 and different. There is a schematic link in the first post.
Here is a photo of someone else's unit of same Lead model. It's hard to see but it also has the 2 resistors (one on each jack).

[meathane]

I have a multimeter, is that how I would probe for signal? We have 240v in the uk, I’d be a bit nervous about probing around whilst the amp is on

here’s a picture of the 2 resisters and wiring on the jacks themselves, it looks the same as in the photo above

I’ve exceeded my upload quota, hopefully you can see the image here https://i.ibb.co/Y4qzN681/IMG-8295.jpg

Edit - in fact, it appears my wires from the jacks go to the opposite places on the board. In my image, the black and white wire is going from the low input in to the smaller cap, and the black wire from the faulty high input goes to the 470n/160V cap Although simply switching the inputs shouldn’t make much difference right? Apart from them being labelled wrong

[g1]

For this particular amp, Low and High inputs seem to refer to frequencies. Low would be for more bass and would connect to the 470n capacitor. Swap your 2 wires around at the capacitors. Then check which input is not working. This will tell whether the problem is at the jacks, or at the circuit board end.