JP23 v1.5

Ok I'm kind of at my wits end here.

Got a JP23 v1.5 on the bench with an illuminated protection light on. Class D type 4. No output mosfets blown, but the output filter inductors had gotten a little warm and melted the factory applied insulation. I assumed the inductors had shorted out.

Removed the inductors, unwrapped 1.5 turns, applied my own heat shrink to the exterior of the wires, rewrapped the inductors and tested inductance. 0.13mH with 0.8ohm resistance on both. Soldered both back in and tested. Amp came out of protect!!

Shut down amp, ziptied both inductors in place tightly the repowered on and the amp is back in protect. Oooook.

Repeated previous procedures two more times and amp refuses to come out of protect. I cannot find any place were the inductors are shorting out.

What gives?

How do I proceed at this point?
Could the iron core inductor downstream of these two inductors cause this fault? Moving the inductors by hand has no impact, and I have both suspended slightly above the board so that they can't short there.

Just checked the legs of the voltage regulation mosfets 7912 and 7812. All legs have the same 6.8v dc on them. Is this a result of the protection being engaged or is the cause of the fault?


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