Measure the gate to source resistance for the PS FETs again.
Were your resistance values ohms or k-ohms?
Were your resistance values ohms or k-ohms?
On Q7-Q8-Q9, I get the same reading both way g-s and s-g
On Q10-Q11-Q12, I only get a reading from s-g. From g-s I get ol
On Q10-Q11-Q12, I only get a reading from s-g. From g-s I get ol
Would bad fets cause the fuse to blow when the amplifier is off. The fuse blows as soon as power is connected, thats what led me to believe it was the blown trace.
Q8 at 2.2 ohms was definitely bad. The readings for the 2 banks of FETs should read the same. That's why I suspected the drivers. Did you check the drivers for leakage and open junctions?
I'd pull the drivers again and recheck the gate to source resistance. You should also pull the FETs to check them out of the board to confirm that they're not shorted or leaking from the gate to either of the other terminals.
I'd pull the drivers again and recheck the gate to source resistance. You should also pull the FETs to check them out of the board to confirm that they're not shorted or leaking from the gate to either of the other terminals.
All the PS fets other than Q8 are good
Q7, S-G=OL, G-S=OL, S-D=4.09m-ohm
Q8, S-G=2.8, G-S=2.8, S-D=2.8
Q9, S-G=OL, G-S=OL, S-D=4.04m-ohm
Q10, S-G=OL, G-S=OL, S-D=4.08m-ohm
Q11, S-G=OL, G-S=OL, S-D=4.05m-ohm
Q12, S-G=OL, G-S=OL, S-D=4.04m-ohm
Q7, S-G=OL, G-S=OL, S-D=4.09m-ohm
Q8, S-G=2.8, G-S=2.8, S-D=2.8
Q9, S-G=OL, G-S=OL, S-D=4.04m-ohm
Q10, S-G=OL, G-S=OL, S-D=4.08m-ohm
Q11, S-G=OL, G-S=OL, S-D=4.05m-ohm
Q12, S-G=OL, G-S=OL, S-D=4.04m-ohm
With those and the drivers out of the circuit, what do you read g-s on the pads on the board?
Did you check the drivers for leakage and open junctions?
Did you check the drivers for leakage and open junctions?
I did check the drivers for open gates and leakage, all test good
The g-s on thee board for the ps pads reads ol on all, q7-q12
The g-s on thee board for the ps pads reads ol on all, q7-q12
I believe I am misunderstanding you, did you want me to check the open pads on the board ?
Or the g-s on the ps fets both in circuit and out to compare?
Or the g-s on the ps fets both in circuit and out to compare?
Yes, open pads.
You checked the non-Q8 FETs and all read open. Something was causing the G-S to read different for the two banks when you had the FETs (minus Q8) in the circuit,. I'm looking for whatever is causing the differences.
You checked the non-Q8 FETs and all read open. Something was causing the G-S to read different for the two banks when you had the FETs (minus Q8) in the circuit,. I'm looking for whatever is causing the differences.
Those readings were in circuit, I can resolder and recheck.
Should I leave the driver's q2,q3,q4,q5 out of circuit?
Should I leave the driver's q2,q3,q4,q5 out of circuit?
Do whatever you need to do to repeat those readings so we can try to find what's causing the difference between the banks (if there actually is one).
Okay everything is back in circuit
Q7, g-s 6.3 ohm, s-g 6.3
Q8, g-s 2.8, s-g 2.9
Q9, g-s 6.3, s-g 6.3
Q10, g-s 39.1 m-ohm, s-g 9.3 m-ohm
Q11, g-s 39.08 m-ohm, s-g 9.3 m-ohm
Q12, g-s 37.18 m-ohm, s-g 9.3 m-ohm
Q7, g-s 6.3 ohm, s-g 6.3
Q8, g-s 2.8, s-g 2.9
Q9, g-s 6.3, s-g 6.3
Q10, g-s 39.1 m-ohm, s-g 9.3 m-ohm
Q11, g-s 39.08 m-ohm, s-g 9.3 m-ohm
Q12, g-s 37.18 m-ohm, s-g 9.3 m-ohm