Does something seem wrong here

[Northwinds]

Since there is no section for sound processing components, I am posting this here

I have a Audio Source EQ One Series II in beautiful minty shape that has an annoying hum when installed in my system that causes a hum in my system even when powered off. I discussed this awhile back and it was suggested that I flip the power cord polarity. Already tried that and it did nothing to solve the problem. I surmised it has to be a ground issue but when I opened up the eq, all grounds seem to be intact with no loose solder joints. Anyway, I shelved it for awhile but out of boredom, I opened it back up to day and discovered this

Last image shows the length of the jumper but the first two images show each side clearly. It looks like someone moved the wires as seen by the leftover solder blobs on the posts by the relocated wires. Could this be the problem? I am at wits end trying to fix this myself as I have no testing tools other then a analog meter that does not work correctly. If someone here would be willing to get this back in operating condition, I would really appreciate it. I hate the fact that it sits unused. Nothing on the boards looks burnt, no wierd smells, no other work done to it other then what is imaged above. Not sure what the guy was attempting to do here

 

[Northwinds]

You may notice a black ground wire on the rightside but for some reason, there is no black wire on the other end

 

[laatsch55]

That's probably to prevent ground loops. For the same reason when running shielded twisted pairs internally to hook the inputs to the volume pots, the shield gets hooked up to one end only, and that's only at the ground end.

 

[Northwinds]

Understood... ok how about this, see all those little capacitors??? with the brown coating on the wire leads? If one is touching an adjacent one, would that cause an issue, I found two of them leaning into each other making contact, you can see them in the second image. The ones I am referring to are in different locations of the board. I pushed them apart gently

This is driving me bananas, I want to use this in my system

 

[laatsch55]

Hum issues are a sumbitch even with the unit in front of you. Without a meter and possibly a scope damn near impossible. Electro's touching one another should not be ab issue unless they touch on top where the shiny, conductive covering is.

 

[laatsch55]

It could be any one of those op-amps too...

 

[NavLinear]

Understood... ok how about this, see all those little capacitors??? with the brown coating on the wire leads? If one is touching an adjacent one, would that cause an issue, I found two of them leaning into each other making contact, you can see them in the second image. The ones I am referring to are in different locations of the board. I pushed them apart gently

This is driving me bananas, I want to use this in my system

If there is an R designator than they are resistors but the board also has some color coded discrete components that are in the J (Jumper?) designated locations. They could also be resistors but they are shaped differently than the other resistors in your photos. The brown stuff on the leads is an insulator. Moving them apart was the correct thing to do but that should not have been a problem assuming the contact point was insulated.

The cable that goes between the pots sure seems like an add on - either a trace that was left out of the production board or maybe a repair for a damaged trace. Like Lee said the two conductor cable is shielded with the shield terminated on one end and floating on the other - this is a pretty common method to avoid grounding issues.

 

[Northwinds]

What/which are the op-amps?

I called Audio Source. They only cover back to stuff when Phoenix Gold was acquired, I assume that was in the 90s. This one shows a build date of 2-15-85 so it's birthday is tomorrow LOL!!! Anyway, customer rep dude gave me the number of a past employee named Alex. I guess he owns Alster located in Portland, OR and they specialize in Phoenix Gold, Audio Source and Carver repairs. Looks like they do a lot of car audio too. Left a message, maybe it's a common repair and he can give me a general idea of what to look for without bungling through with a POS meter and a blank stare at just the jargon you guys bandy in threads

 

[Gepetto]

What/which are the op-amps?

I called Audio Source. They only cover back to stuff when Phoenix Gold was acquired, I assume that was in the 90s. This one shows a build date of 2-15-85 so it's birthday is tomorrow LOL!!! Anyway, customer rep dude gave me the number of a past employee named Alex. I guess he owns Alster located in Portland, OR and they specialize in Phoenix Gold, Audio Source and Carver repairs. Looks like they do a lot of car audio too. Left a message, maybe it's a common repair and he can give me a general idea of what to look for without bungling through with a POS meter and a blank stare at just the jargon you guys bandy in threads

Can they provide you with a schematic?

 

[Northwinds]

He said some engineer guy was off until Monday so I will call back and see if they have any available. Seems wierd I can't find one online somewhere but I have been looking