Need Help with my Ampeg Jet II "J12-T" reissue.

[ZahnnasPapa@aim.com]

hello all, i set this account up today in hopes of fixing my Amp

It is an Ampeg J-12T reissue.

the problem occurs quite often and has been overhauled once by a buddy, and once screen resistors were replaced, he now now has moved away.

whenever i plug in it screams bloody murder at me, wails, whines, crackles. it is completely unplayable.

when i apply downward pressure on the cord into the input it can be played.

when i turn it off the amp it crackles and swells into a whine and thumps my speaker quite hard ,before drifting completely off.

it hasn't been played past 4 on the volume dial, i know this amp will blow at high volumes.


i have all the proper equipment, soldering iron, solder, a tester, schematic. i suppose i should dive in.

but what can the collective wisdom of the forum tell me before i go for it?

[52 Bill]

Welcome to the place.

when i apply downward pressure on the cord into the input it can be played.

If pressing on the input fixes the problem, I would start by checking for broken solder joints on the input jack.

[Jazz P Bass]

So would I.

[dporto]

The pcb's are pretty weak on these amps - especially in areas where there is repeated stress (ie. plugging and unplugging a guitar jack). Definitely re-solder and/or replace the crappy input jack with an all steel switchcraft or similar for a start - I bet you'll be happy!