Fender Vibro Champ XD - reverb/delay settings making digital noise!

[acorkos]

Fender Vibro Champ XD - everything works normally, except when the DSP effects are in a reverb or delay setting....then there is this digital static squealing noise, some settings worse than others, volume is dependent on the effects level setting. Chorus (without combined delay or reverb), Tremolo and Vibratone settings operate normally without noise....just the reverb and delay settings are affected.

I thought I had it solved when I plugged in a cable to the line out jack, to hear the preamp through another amp. For a couple of hours it was working normally again, in all DSP effect settings. But I tried it again a couple of days later and the original problem is back. I cleaned the line out jack, tugged on it, tapped on the PCBs and individual components with the amp operating...can't get rid of the digital noise in delay/reverb settings.

Any ideas? Thanks for your help...

[Enzo]

Probably the DSP card. If it is intermittant, then I'd first suspect a failed solder joint on one of the LSIs.

[acorkos]

...I'd first suspect a failed solder joint on one of the LSIs.

Is there a way to cook this DSP PCB in an oven to reheat the solder joints? Someone told me he did this to his Mac laptop motherboard...??

[The Dude]

I can smell the surface mount electrolytics already! Nope. I would not try that. I have had some luck narrowing down which chip by using a chop stick or something of the sort to push down the suspected IC -see if contact is then made and amp starts working. You can sometimes narrow it down to a specific chip or area. Then resolder only that chip.