1176 Rev A Output issues

I'm having trouble finding a current thread regarding the Hairball BS 1176.  I'll post one and hopefully someone knows where the answer may be.

Anyway, just finished the build, cleaned up the wiring, calibrated, all is fine.  As soon as I attempt to test with a real track, I find that engaging the attack DRAMATICALLY reduces the output.  Also turning the output up past 24 results in a pop and nasty interference, pretty much with no output.  Completely reset the trim pots and tried calibration again, voltages on the money.  Same issue persists.  With the attack off, signal is fine until the same output threshold is reached, then the pop and noise is there once again.  Everything on the PCB looks fine, nothing is melting, no smoke.

Help?

ashtonv19 said:

With the attack off, signal is fine until the same output threshold is reached, then the pop and noise is there once again.  Everything on the PCB looks fine, nothing is melting, no smoke.

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This sounds like oscillation. Check input/output wiring, make sure you use shielded cables and don't route output wires near input circuits. The FET input stage is quite Hi Z and easily picks this up.