Another skar 4500RP stuck in protection.

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Ok guys so with the amp it came to me in protect mode I check all power supply mosfets they tested good I tested all output mosfets they tested good I removed the rectifiers in the amp stays in protection so I remove the output mosfets that amp powers on I put one output mosfet per Bank the amp goes back into protection I've replaced the driver ic's but the amp stays in protection I have all low voltage's present.

So I try removing r-21 on the output driver board the amp still stays in protection however if I remove Q 226 the amp will power on so I've checked nearly every component of the protection circuit connected to the DC offset and still have had no luck.

I now have the amp hookup with a low voltage Supply running off of one of the Transformers as I've learn in class D type 3 tutorial I have positive 15 volts and -15 volts connected to the rail caps the amp will power on but soon after the relays engage the light bulb in the low voltage Supply start to Glow brightly so I shut it down the amp and I've been pulsing the amp on and off and probing the output mosfet legs and I have negative rail voltage on the high side gate and Source pads I don't have any DC voltage on the speaker terminals or the inductors before the amp goes into protect I've tested the rail caps the output filter caps just about anything on this amp and cannot find the issue however I'm still fairly new to Amp repair and I figure it's time to reach out for help any help would be appreciated thanks
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Perry I put q226 back in because the light has never lit up for me before on other amps and I didn't want to risk damage to the amp but it would go to negative rail on high and lowside then the light would illuminate.

However I pulled the Mylar 10uf capacitors out to test them an they test fine but now with them out the amp will power up and try to stay on and it will produce waveforms but as soon as it trys to oscillate it goes in protect But I did take pics of waveforms by cycling the amp on and off. PICS BELOW


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Yes I have the same signal on the other Banks I just put new drivers in because I thought it may be bad driver ic's.

But I was thinking maybe it is my I inductors because everything else in the amp checks out I did a inductance test on them in the board and both read 0.01mh 86.6 resistance.
Okay Perry the amp will power up and stay powered up with no protection if I disable One IC doesn't matter which one it is however I have positive and negative rail voltage where they need to be but I have no low side Drive I've tried to trigger the scope in but I'm just not getting anything.

If I disable both Ic's it's the same thing should I put the mylar caps back in the board and redo the test?

Pics below of inductance reading off lcr-meter.


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It don't have a scale setting and as far as accuracy I believe it to be a little off on capacitance and a few other things it's usually 10 to 20% off I'll test a couple other inductors and see real fast what the readings are I don't use it too much for inductors luckily I don't run across a bunch of shorted inductors
I don't see a square wave anywhere but there is some signals on pins 7,11,12,13

Pics below scope settings are 10us/1v probe x10

Also I forgot to mention when I power amp on after its been off for a few mins ill flip the switch it goes in protect But if I flip switch off and back on them amp powers up an stays on.


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Ok I found out the reason I had negative rail on the highside there a diode between the relays for the remote on and I had put it in backwards when I tested it I wasn't sure how it went in so I tried my best to guess so I was thinking about that and looked at the aq20 schematic and realized it was backwards so I flipped the diode around and now I have positive and negative rail were they should be no longer is there negative voltage on the high side.

So I took the jumper off the Ics and the amp tries to come on as soon as lowside drive try to appear on the scope the amp goes in protection before the relays even engage but if I shut down the Ics that and powers on and stays on.
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