Help needed to fix PPI 900.4 Wont turn on

[yusme]

Well it looks like the ppi 900.4 had a problem so far I manage to take out all the fets and test them with a multimeter and 2 IRFI4212H are gone and all The T460 are bad so Im waiting in the replacement parts.

Now do you guys think there could be something else related that caused this problem and might need to be replaced?

The amp dosnt look burnt anywhere but I want to make sure I test everything possible before I put replacemnets back in so that I dont re toast all the components.!

here are some picts after The fets where removed also do you guys know how can I test the square items that are next to the power mosfets should I even worry about them?? (They are present inside a red square that is next to the red square where the power fets go )

 

[nigelwright7557]

Most people on here recommend a mains lamp in series with your amplifier to reduce the max current the amp takes.

Its not always enough to just replace obvious blown components as it might be something else that has caused the fault.

 

[yusme]

but do you have any idea what could cause the two of the power source fets to go plus all the output fets ??

 

[yusme]

can you please explain what u mean with mains lamp in series

 

[theAnonymous1]

The cubes are inductors. Highly unlikely anything is wrong with them.

You might want to replace the IRS2092 on the channels that had the blown IRFI4212H.

 

[yusme]

can u tell me wich are the IRS2092 dont know where are those located ??

 

[theAnonymous1]

The row of four 16-pin ICs in your third pic.

 

[nigelwright7557]

I have designed a few irs2092 based amps.
I found if the mosfets went often the 2092 had gone as well.
So I always replaced mosfets and 2092.
I always used DIP version and socketed them for easy replacement.

 

[yusme]

oh man thats alot I think often its cheaper to just save up the time and the money it will take to fix the amp and buy a new one.

Im thinking after I change the IRS2092 probably there was something else that caused all this in the amp but I cant figure it out sadly I dont have an oscilloscope to check the circuitry, sad that was a good amp

 

[yusme]

Hi guys well I got the IRS2092S, IRFI4212H and the AOT460 I will be replacing all these in the amp from the pictures above do you guys think I should change anything else??

 

[nigelwright7557]

Hi guys well I got the IRS2092S, IRFI4212H and the AOT460 I will be replacing all these in the amp from the pictures above do you guys think I should change anything else??

I am guessing the AOT460 is a gate driver transistor.
There should be two transistors driving the gate a npn and a pnp.
If replacing one I would replace the other too.

 

[theAnonymous1]

I am guessing the AOT460 is a gate driver transistor.
There should be two transistors driving the gate a npn and a pnp.
If replacing one I would replace the other too.

The AOT460 are the FETs for the power supply. The IRS2092 doesn't require gate buffers to drive IRFI4212H.