First I would move those gate resistors from the board and solder them directly to the gate lead of the mosfets.
This may not fix your problem but it will stop the amp from oscillating
Edit: I meant to say gate resistors (not source).
This may not fix your problem but it will stop the amp from oscillating
Edit: I meant to say gate resistors (not source).
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It took a while to get a handle on your wiring, nothing jumps out except the gate stoppers.
Did you actually measure the 3 watters before you installed them?
Your voltage readings cannot be correct if Rg is smoking, check your meter.
Also, check the gate voltage again, this time from the neg rail to R11 or R12.
Did you actually measure the 3 watters before you installed them?
Your voltage readings cannot be correct if Rg is smoking, check your meter.
Also, check the gate voltage again, this time from the neg rail to R11 or R12.
Sorry to flog a dead horse here.
Before you do anything I would be moving those gate resistors from the pcb and soldering them to the gate lead of the mosfets.
Before you do anything I would be moving those gate resistors from the pcb and soldering them to the gate lead of the mosfets.
Hi D,
Are both your gate voltages about the same? If so, you need to crank up P1 until you get around 4v on both. Then check the drop across Rg and trim.
Are both your gate voltages about the same? If so, you need to crank up P1 until you get around 4v on both. Then check the drop across Rg and trim.
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I do as you say and at the extreme of p1 I reach 3.9v at R11 Also the voltage accross the 100r (10w) goes down to 0.9v . However they are still pretty hot to the touch which i wouldnt expect .
Im not sure if it would make a difference but i have a thermistor inline with my psu ground to earth..
Then Rp is too big, ain't it.
What is the value of you resistors under the input pair. 1K I hope.
What is the value of you resistors under the input pair. 1K I hope.
OK, so they are both 3.9v, thats 7.8ma through the 2sj74. You need to lower Rp to around 1.2k unless the Idss is too low anyway. Then you would have to increase R7 to around 1.2k.