There is rarely an amp that will go into protect due to a fault with the power supply.
Which pin on the 393 on the PS board is driving the amp into protect?
Which pin on the 393 on the PS board is driving the amp into protect?
It was going into protection with the rectifiers removed. If it go back into protection when I install one FET per bank I’ll let you know.
It could be virtually anything that's causing it to go into protect. The protection circuit could be defective.
I had thought about that possibility as well. Removing the power supply mosfets allowed the amp to boot up and produce a square wave. I thought that indicated that the protection circuit wasn’t damaged. At least none of the components on the PWM board. Is that a foolish conclusion?
However. Earlier, before all this business with the power supply section, the amp was shorting output mosfets on the right side of the motherboard, after I repaired the output driver card. I replaced those output mosfets, built the low power, power supply and then the amp wouldn’t stay on long enough to even build a square wave. I pulled the rectifiers when I built the low power, power supply.
I had to remove all of the power supply mosfets just to get the amp to come to life enough for me to check for a square wave in the power supply.
I have worked on 4 of the DD amps and 2 have gone perfectly and 2 have given me a fit, counting this one, so I don’t have much experience with these amps. They can be quite the challenge.
Thanks for your help and support. I’ll pick up on it again tomorrow. It’s past dinner time and I’m pretty tired. Best to quit for now and pick up on this while I’m fresh tomorrow.
However. Earlier, before all this business with the power supply section, the amp was shorting output mosfets on the right side of the motherboard, after I repaired the output driver card. I replaced those output mosfets, built the low power, power supply and then the amp wouldn’t stay on long enough to even build a square wave. I pulled the rectifiers when I built the low power, power supply.
I had to remove all of the power supply mosfets just to get the amp to come to life enough for me to check for a square wave in the power supply.
I have worked on 4 of the DD amps and 2 have gone perfectly and 2 have given me a fit, counting this one, so I don’t have much experience with these amps. They can be quite the challenge.
Thanks for your help and support. I’ll pick up on it again tomorrow. It’s past dinner time and I’m pretty tired. Best to quit for now and pick up on this while I’m fresh tomorrow.
It could be virtually anything on the audio side if it only has a problem when there is rail voltage. The DC offset is a common fault. The transistor (Q226?) fails and causes the amp to go into protect.
If you take the time to study these amps (not just get them working) you can get through the repairs much easier. Fortunately, they're cloned by many manufacturers so you're learning about a large percentage of amps. Spend a couple of days doing nothing but analyzing the diagrams and understanding the individual circuits that make up the amp.
If you take the time to study these amps (not just get them working) you can get through the repairs much easier. Fortunately, they're cloned by many manufacturers so you're learning about a large percentage of amps. Spend a couple of days doing nothing but analyzing the diagrams and understanding the individual circuits that make up the amp.
I installed 4 power supply mosfets and amp goes into protection.
Here are the pin voltages on the 393.
1) 7.47v
2) 2.50v
3) peaks at 4.20v and slowly drifts down to 2.6v
4) ground
5) 1.06v
6) 3.68v
7) 115mv
8) 14.5v
Here are the pin voltages on the 393.
1) 7.47v
2) 2.50v
3) peaks at 4.20v and slowly drifts down to 2.6v
4) ground
5) 1.06v
6) 3.68v
7) 115mv
8) 14.5v
The voltages at the pins of the the PWM card from left to right.
1) 14.50v
2) 4.65v
3) 14.27v
4) 14.00v
5) 0.00v
6) 14.50v
7) 0.07v
8) 0.00v
9) 0.00v
10)3.73v
11)4.42v
1) 14.50v
2) 4.65v
3) 14.27v
4) 14.00v
5) 0.00v
6) 14.50v
7) 0.07v
8) 0.00v
9) 0.00v
10)3.73v
11)4.42v
With the amp in protect, what's the DC voltage on all pins of the 393 on the audio driver board? Black probe on the negative rail or shunt resistors.
I get zero volts on all pins of the 393 on the output card.
No rectifiers installed and the low power power supply is not installed. Amp is in protection.
No rectifiers installed and the low power power supply is not installed. Amp is in protection.
I’m getting about 1.6 megohm between the two cathode locations.
David
P.S. I miss read your previous question.
David
P.S. I miss read your previous question.
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