OK, this is perfect, Thank you.
Your outputs are IRF-640 and IRF-9640 This amp uses both P and N junction outputs in groups of three.( Each group of three is arraigned to act like one big fet)
In the group that reads bad you probably have a single shorted fet, and it will cause all three to read shorted.To be safe I replace all three of those devices. < costs about 60 cents for me, I buy bulk>
Your coils are most likely OK But I would do a extensive visual inspection to determine if the inductor shorted pulling the Fets behind in failure mode. Look for any signs of Arcing and any abraded insulation on the windings. If there is none, then lets look elsewhere for troubles.
With the bad fets removed retest the coils again, you shorted reading should go away if not we will get back to this later. make a note, and lets look a bit further for trouble.
Now heres the sticky part.
These Fets could have caused damage to the driver card and chip on that card that drives these fets. These cards as I recall are a off the shelf solution from 3S corporation overseas, They have a website if you goggle it.
Anyway, this card can become damaged when the fets fold over on themselves. This is a PG part, and I am doubtful that you will find another source in the states for this card or the correct parts on this card.
Most tech's drop in a new tested card for speedy tech work and cost savings in labor. This is why PG repair services can be a very favorable alternative in many cases.
Now with the bad fets removed and the power supply repaired you should be able to do a "limited " power test, but this requires a current limited power supply. < Less then 5 amps is all that is need to fire this amp up and bring it to idle with NO signal or load connected....
If you can do all this and have the current limited supply, then you should be able to test with a voltmeter to see what voltage is going to the Gate lead on the bad fets that you removed. < It should be the same signal as the other fets get to their respective gates.
If NOT then your card is most likely defective, and you will need to get PG to supply you one. Use speaker ground on terminal 1 and 3 as your ground test reference point when reading the fet gate drive signals. The gate drives should read about the same for each bank of similar fet devices so you can compare to the other bank of devices with matching numbers.
If the signals are not the same, then I would say the Driver card is possibly damaged. and your at a stopping point to try and get PG to sell you one....
DO NOT test this amp without a CURRENT limited supply with a 5 amp maximum. You don't need anymore than this at 12 volts, and there is some hefty juice in there when its on, you can blow the tip right off you voltmeter probe so PLEASE be careful.
If you signals match then turn it off and let it sit for a good while till it discharges the power supply, Then replace the bad outputs, reassemble the clamps and test again with a current limited supply.
A 5 amp supply will yield enough power to drive most any woofer loudy at your test bench, and it will save big damage if we missed something along the way.
Any questions so far?????
Good nite... 