HELP!! Extra wire left on my amp????

[Scorpion1]

I'm not very good at electronics, but i was moving my amp guts to another cabinet and now I have an extra wire??? Out of the transformer(?) i think. Where does it go to?? Its sounds like crap now too, Crackly and weak.

 

Help, Thanks

[curtisa]

The two leads with the ring lugs need to be bonded to the metallic frame of your amp.

The extra wire from the transformer is probably the centre tap of the secondary winding (the two yellow leads) and likely needs to go to the frame aong with the two earth leads. A schematic would help though. What kind of amp is it?

Quick check - set your meter to AC volts and measure between the extra wire and each of the two yellow wires from the transformer (carefully! The extra lead could be at mains potential). If you get the same voltage between one black/yellow pair and the other black/yellow pair it's probably the centre tap and will need to be grounded.

[curtisa]

Just noticed there is a beige 3-pin plug on the circuit board where you've reattached the two yelow wires. My guess is that the extra wire from the transformer goes to one of the pins on that connector - perhaps the yellow wires came from the two outside pins and the black wire from the centre pin?

[Scorpion1]

Thank you mate, The tan "thing" is in fact a 3 pin plug which was not used. I did find an extra wire on the floor that had the extended end i made and the other end was the short original wire that was not cleanly cut, It clearly broke off of the board. Is there a way to connect it to the middle pin without frying something, a way to check...........ohms etc?????

 

Oh, and btw, the larger wires like the yellow for example are extension wires i added.

Edited April 26, 2016 by Scorpion1

[curtisa]

The AC voltage check I suggested a bit further up is a good start, but without knowing what the circuit looks like in more detail I can't really say where the wire came from originally.

Measuring ohms between the black wire and each of the two yellow wires should yield equal resistance (maybe a few ohms each?) if the wire is what I think it is, but you still need to find out where it came from.

Maybe have a close look at the circuit board and search for broken solder joints, or a solder joint with a tuft of strands poking out of it that may have had a wire attached at some point?

[Scorpion1]

OK, checked what i could and the 7 volt readings didnt help me much. But I did find out that the extra wire has to do with the gain/distortion switch on the amp based on it sounding terrible set there. It sounds fine on the clean setting so i will just keep it there and use my foot pedals for any effect adjustments. Thanks