GAS PSP3500.1d going into protect

[LatvianVideo]

Id assume it was a random failure, but i dont know what failed first, the IRFB7437 the 27324 was driving or the driver itself failed first. I guess ill upgrade to the 27524

 

[Perry Babin]

If the PS FETs have pull-down resistors, you may want to try powering the amp up to see if it will produce drive to the inputs of the driver IC after it's been removed.

 

[LatvianVideo]

When the dead driver was in place, it was sending something into the both of the inputs. So id assume it also will send when its gone. I guess ill hook it up, check that and more, then reassemble the amp (ill be taking it to a different city with me)

 

[LatvianVideo]

Sending pulses like this to INA and INB, but im not sure about the voltage, as its about 1.4v in the osclilioscope, that means it would be about 92v before my (~65.5x) voltage divider

 

[Perry Babin]

Use your multimeter. What DCV do you read on those inputs?

Is the protect LED still lighting up?

 

[LatvianVideo]

with a multimeter its more normal, 2.29v, ill assume the osciliscope is just freaking out. Still going into protect, as it has no driver lol (also the middle pin of the rectifiers is desoldered, gonna resolder that when i get the new driver)

 

[Perry Babin]

How long until you get the driver?

Do you know if this amp lights the protect LED initially, for a couple of seconds) under normal operation?

 

[LatvianVideo]

ill get the driver on monday/tuesday probably, the store is closed on weekends. When powered on, it cycles thru all of the 3 LEDs, i assume that is how it normally starts up. After that the power and protect flash indicating the issue

 

[LatvianVideo]

****, replaced it, still no work, but a different error. Was power and clip LED on at same time. was testing if its generating a signal and stuff, then a mosfet goes boom. I no longer know what could be wrong

 

[LatvianVideo]

Very ugly solders because i dont have my new tip i ordered, but had no shorts and all connections were good. I no longer have any idea what could be wrong with this amp. When it generates a voltage, it blows up???

 

[Perry Babin]

Were the rectifier output terminals still out of the board?

Of the remaining PS FETs, what's the resistance gate to source?

 

[LatvianVideo]

the rectifiers were connected. gate to source is 2-11ohm in the dead bank (4 mosfet), 1k in the other bank.

 

[Perry Babin]

Find the FET reading the lowest and pull it, then recheck.

Pull the rectifier terminals again.

 

[LatvianVideo]

removed the dead mosfet, now 1k ohm everywhere. Between drain and source there still is an increasing resistance, source is connected to ground

 

[Perry Babin]

Did the driver survive?

Did you order extras?

 

[LatvianVideo]

Driver seems to have survived, no short between Vdd and ground. No extras of anything

 

[LatvianVideo]

Am at a place with some old german analog oscilloscope, can see that there is a square wave on the input of the driver, there is something on the output on the healthy bank, some weird output on the one that died, At 0.1v looks similar to the healthy one, but at 0.05v they are very different, so idk if it died or not then

 

[Perry Babin]

An old German scope is much better than working blind.

If the IC has two good inputs, a good signal on one output and not on the other, it likely failed.

With a multimeter, what do you read (DCV) on the two inputs and the two outputs?

 

[LatvianVideo]

The psu i have here isnt good enough, i dont trust it enough to connect to a battery tho.
Before it shuts off due to the psu:

Input:
A(dead size):1.92v
B:1.99v

Output:
A(dead side):3.15v
B:0v

 

[Perry Babin]

It's odd that you are seeing less than the 2.29v that you read earlier but the duty cycle could be different.

Are you still using the supply that was a solid 12.5v?