Got this amp in the guy said he touched the rca shield ground of the amp to the power wire by accident .
The amp still comes on and plays but has noise and pops through the subwoofers . He already changed head units but the amp still has the issue .
Any ideas on where to start ? Nothing looks burnt and everything I’ve checked so far tests good
The amp still comes on and plays but has noise and pops through the subwoofers . He already changed head units but the amp still has the issue .
Any ideas on where to start ? Nothing looks burnt and everything I’ve checked so far tests good
Yes amp was working perfectly until he touched the power wire to rca shield ground .
I notice that I get 8 volts of dc on the shield grounds . When I measure the voltage on the rca ground shield just letting the meter probe touch the shield ground makes the amp draw excessive current
If I hook rca shield to main ground there is no change . I noticed the outputs get very hot same with the power supply fets .
Pulled the outputs no change to the amp . Still draws 20 amps of current and the power supply fets get hot within 10 secs
Are the rectifiers shorted?
If you lift the center legs of the rectifiers, do you still have excessive current draw?
If you lift the center legs of the rectifiers, do you still have excessive current draw?
Yes if I pull the center legs of the rectifiers the amp still draws excessive current and the fets get hot
Are the FETs for both transformers getting hot?
Do you have a clean drive signal going to all of the FETs?
Do you have a clean drive signal going to all of the FETs?
The amp uses different FET gate resistors for the two sets of FETs. The one that's heating uses the higher value FETs for both banks. In some instances, replacing the 60.4 ohm resistors with the 47.5 ohm will solve the problem. If nothing else, it will tell you if the problem is elsewhere.
Replaced the 60.4 ohm resistors with 47 ohm .
The current draw went away but the fets for 1 transformer still get hot after 30 secs . Is this normal or do I still have an issue somewhere ?
The current draw went away but the fets for 1 transformer still get hot after 30 secs . Is this normal or do I still have an issue somewhere ?
Is this for the transformer that has 1/2 of the gate resistors 60.4 ohms?
If so, it may be normal.
Do all gate signals on the gate legs of the FETs look good?
If so, it may be normal.
Do all gate signals on the gate legs of the FETs look good?
The transformer that had all 60.4 ohm resistors Is the one I’m referring to . The fets still get warm and the transformer wines like crazy still
But the idle current right now is about 4 amps . Here is what I get for the drive signal on those fets .
scope set to 10us 5volts/Div
But the idle current right now is about 4 amps . Here is what I get for the drive signal on those fets .
scope set to 10us 5volts/Div
Attachments
It's odd that some cycles appear to have too little deadtime but if that was true, both transformer's FETs would heat up.
Are the rectifiers back in the circuit?
What's the DC voltage at the B+ and ground terminals?
Are the rectifiers back in the circuit?
What's the DC voltage at the B+ and ground terminals?