Marshall MG100 HDFX Effects Problems

[SleazyE]

I have a Marshall MG100 HDFX solid state amp, the clean and overdrive work, but the effects including reverb don't. I've tried using a patch cord from effects send out to the return, and it doesn't trigger the effects. I've used the foot pedal on different amps, and it works as well (Which is the only way to turn on/off effects) How do I pin point what chip or component is at fault?
Thank You

[Enzo]

If the amp works but the FX and reverb don't, then it looks like either IC3 is bad or the DFX card is. Make sure there is good +5v to the DFX card as well.

[SleazyE]

Thanks

I appreciate it, thank you for the schematic and info