Weird effects pedal - amp interaction

[thinman]

One of our guitarists stood on his lead and snapped, internally, the 1/4" jack on the front of his combo.

I replaced the jack for him but since then he gets a strange interaction between his Boss GT10 board and the amp - there's a horrible sort of oscillation in the sound.

A guitar straight in to the amp sounds fine. The pedal board plugged into the effects return is oscillation free too. We've tried a new set of cables and done a factory reset on the GT10.

The GT10 is also fine into a different amp. It seems to be a strange interaction between the amp and GT10.

The amp's always been a bit strange in that it seems ultra sensitve - e.g. with a lead not plugged into a guitar, touching the tip causes a really loud pop on the amp.

Any ideas anyone?

[Paul_C]

[quote name='thinman' post='744284' date='Feb 13 2010, 07:59 PM']One of our guitarists stood on his lead and snapped, internally, the 1/4" jack on the front of his combo.

I replaced the jack for him but since then he gets a strange interaction between his Boss GT10 board and the amp - there's a horrible sort of oscillation in the sound.

A guitar straight in to the amp sounds fine. The pedal board plugged into the effects return is oscillation free too. We've tried a new set of cables and done a factory reset on the GT10.

The GT10 is also fine into a different amp. It seems to be a strange interaction between the amp and GT10.

The amp's always been a bit strange in that it seems ultra sensitve - e.g. with a lead not plugged into a guitar, touching the tip causes a really loud pop on the amp.

Any ideas anyone?[/quote]


take to someone who knows about amps ?


after all, you don't know if the shock to the board when the jack was broken did other damage to components that only someone with some knowledge can identify

I repair guitars/basses etc. but if it's a circuit board problem I'll always pass it on to a qualified engineer - I know not of the wizardry of circuit boards

[thinman]

[quote name='Paul_C' post='744328' date='Feb 13 2010, 09:16 PM']take to someone who knows about amps ?


after all, you don't know if the shock to the board when the jack was broken did other damage to components that only someone with some knowledge can identify

I repair guitars/basses etc. but if it's a circuit board problem I'll always pass it on to a qualified engineer - I know not of the wizardry of circuit boards

[/quote]

I did a HND in electronics some years ago so I'm reasonably comfortable with PCBs etc. There's no signs of cracks on the board but it does have some surface mount stuff that could have been disturbed.

What's so strange about this is that the amp sounds fine with a guitar straight in to the input and the pedal board is fine into other amps. It's the two together that's the problem. Although it's possible I'd expect the amp to sound a bit ropey with guitar only if it's damaged but it doesn't. I keep trying to think what must be different about the signal from the board compared with a guitar - it's set on the board to be the same as guitar output.

[Ancient Mariner]

I'd suspect the new jack socket. With your swapping around did you plug the guitar in direct and have it sound OK, then unplug the guitar, connect the amp with the cable already plugged into it to the Boss and then cable from the boss to the instrument?

[umph]

+1 on jack did you use an isolated one, you could've raised the noise floor.

[thinman]

[quote name='umph' post='744919' date='Feb 14 2010, 04:11 PM']+1 on jack did you use an isolated one, you could've raised the noise floor.[/quote]
The replacement jack is identical to the one that came out.

As I've said - it works perfectly well with a guitar straight in.