If the voltage is below the rated voltage and the correct polarity, it may be excessive ripple.
While powering up (looking across the cap with the scope), is the voltage across the cap pure DC or does it have a lot of ripple?
While powering up (looking across the cap with the scope), is the voltage across the cap pure DC or does it have a lot of ripple?
So, replaced all damaged parts, removed one driver card, and the output mosfets from this channel. If I bridge this 4.7ohm resistor, the amp powers up fine, and the left audio channel also works fine.. But still this resistor burns.. I will try 400 ohm for testing.
It makes no difference, even with 10ohm 4 watts, the resistor burns.. It's a regulated ps with softstart.. It only during starting,
Does C2 heat up with the resistor bypassed?
Soft start shouldn't cause a problem for that resistor.
What FET are you using in the PS?
Soft start shouldn't cause a problem for that resistor.
What FET are you using in the PS?
It's not c2.. It seems like, because the plastic was melting..
Qp6 was burned. It became so hot, That c2 melted. I replaced Qp6 with aBD140.
The fets was original 3205, I replaced with FB260N for testing, but only 4 pieces instead of 16... Gate resistor are 25 Ohm.
Edit: c2 is also blown..
Qp6 was burned. It became so hot, That c2 melted. I replaced Qp6 with aBD140.
The fets was original 3205, I replaced with FB260N for testing, but only 4 pieces instead of 16... Gate resistor are 25 Ohm.
Edit: c2 is also blown..
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Is that with a resistor in the circuit (not bypassed)?
Check this across the B+ and ground terminals to see how much ripple there is there.
Check this across the B+ and ground terminals to see how much ripple there is there.
It's the same at b+. No resistor in circuit. .
Maybe I should install new capacitors in the b+ B- line..
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Maybe I should install new capacitors in the b+ B- line..
.
I'd reinstall a 4.7 ohm resistor and then compare the ripple on C2 vs the ripple on the B+ and ground.
If you have a large capacitor of about 6800uF, solder it across one of the primary filter caps to see if that makes a difference.
Perry, you are the best... With this cap inside, the amp starts without any problems.. Now I can check for the other audio bank..
thank you
so much.
thank you
so much.
For those who may not understand, the primary filter caps are defective allowing too much ripple to be present (the caps weren't doing their job, smoothing the B+ supply voltage).
Installed the obviously defective driver card, and removed mosfets. On the last pin at this drive ic I have a good signal. At pin 6 is nothing.. At the gate pads only rail voltage.
Why did you remove the FETs?
Are you driving a signal into the amp? If not try it and see if you get signal on pin 6.
Are you driving a signal into the amp? If not try it and see if you get signal on pin 6.
What's the DC voltage across G and S of the outputs that are failing?
What's the DC voltage on the drain of the output FETs?
DCV on the IN and FB terminals of the driver board?
What's the DC voltage on the drain of the output FETs?
DCV on the IN and FB terminals of the driver board?
If you short M1A and M2A G-S on the driver board, Does the voltage G-S on all of the outputs go to 0v?