Marshall DSL40CR DFX issues

[ziggy007]

Gday all,

I have the above amp here. Weak output. Essentially no i/p into the PI. All voltages are good and using the Service manual wave-forms are pretty much on spec as well up to the DFX card input Pin1.

I hate admitting defeat but I'm at a loss. Wondering if any of you Marshall gurus have come across these boards failing? Unfortunately the Service Manual doesn't give anything post DFX, just a test point into the PI (which is tiny). I"m hoping I'm just not seeing the forest for the trees, and its a simple/known issue, ( and I can handle the embarrassment)

Thanks
Gav

DSL40CR service manual (1).pdf

[Jon Snell]

If you insert a clean sinewave on the cold side of C45 and the sound is good, check the 3v3 and 12v supplies to the processor IC; DFX. If voltages are stable and correct, purchase a new DFX board.
The PIC chip, (DFX) is not replaceable as it has a proprietory programme within it. The boards might still be available.