Help with Xtant 604X

[kiermee]

Good day,

I have a Xtant 604x that I am currently repairing. The power supply mosfets Q31,32,33 and 34 were blown and burnt. The other remaining 4 mosfets were good when tested. I changed the 4 damaged mosfets and the 22 ohm gate resistors. When I attach the powersupply 12v and ground connection (no remote) the amps draws excessive current. When I recheck the mosfets they are all good. If I remove the 4 mosfets that I replaced and leave in the 4 that were originally good (there are 8 in total) by themselves and reapply power there is no heavy current draw and when the remote is applied the amp powers up normal. Any ideas on this please?

Are the TC4427 mosfet drivers damaged when they blow? I noticed that there are two circuits here, every 4 mosfets has a driver assigned to it?

Thanks in advance for any assistance.

 

[Perry Babin]

It's possible that the driver IC failed. With the 4 FETs out so that the amp will power on without excessive current draw, compare the input and output signals of both drivers. Are the signals from one driver identical to the other?

 

[kiermee]

Thanks for your quick response Perry. I will do the comparison tomorrow and get back to you.

Thanks again

 

[kiermee]

Hey Perry

I compared the good side to the bad side

Good side the driver ic reads as follows

In 1 = 0.8v
In 2 is the same
Out 1 = 12.6v
Out 2 = 12.6v

The bad side

In 1 = 2.36v
In 2 = 2.36v

Out 1 = 2v
Out 2 = same

Thanks

 

[Perry Babin]

The bad side actually looks more like what I'd expect to be good.

 

[kiermee]

Ok thanks will retrace circuit