Hello
I'm new here and new to trying to fix amplifiers as a hobby I have some knowledge of electricity so safe in that way.
I have a C-Audio XR3801 which the "soft start" fuse kept blowing, I am currently checking the mosfets...
Came across two j162 where the ohms reading keeps climbing up between source and drain where the others I've tested so far are showing 2ohms as the service manual says...
Is this a faulty mosfet and if so is there a replacement available instead of replacing with j162?
Hope you can help
Thanks.
Luke
I'm new here and new to trying to fix amplifiers as a hobby I have some knowledge of electricity so safe in that way.
I have a C-Audio XR3801 which the "soft start" fuse kept blowing, I am currently checking the mosfets...
Came across two j162 where the ohms reading keeps climbing up between source and drain where the others I've tested so far are showing 2ohms as the service manual says...
Is this a faulty mosfet and if so is there a replacement available instead of replacing with j162?
Hope you can help
Thanks.
Luke
Very quickly...
I'm assuming these are 2SJ162 which is a lateral type P Channel FET. Modern replacements would be such as Exicon Profusion type:
https://www.profusionplc.com/type/lateral-mosfet?mnf=exicon
https://www.profusionplc.com/parts/ecx10p20
You need to test these out of circuit. They should read open circuit between Drain and Source when measured one way around and like a diode when measured with opposite polarity.
Note... as these are FET's you can not test with the gate floating, you must tie the gate to the source.
I'm assuming these are 2SJ162 which is a lateral type P Channel FET. Modern replacements would be such as Exicon Profusion type:
https://www.profusionplc.com/type/lateral-mosfet?mnf=exicon
https://www.profusionplc.com/parts/ecx10p20
You need to test these out of circuit. They should read open circuit between Drain and Source when measured one way around and like a diode when measured with opposite polarity.
Note... as these are FET's you can not test with the gate floating, you must tie the gate to the source.
Hello.
Thanks for getting back to me.
How do I tie the gate to the source?
Just link it or ground it?
Thanks
With the FET out of circuit you just tag a resistor from gate to source. Anything will work, even something as high as 10 meg.
If the FET is good and you don't tie the gate then you will find that just dabbing a finger on the gate will tend to either turn on or turn off the FET as you charge the gate capacitance up. It will stay in that state for hours until you touch it again. Tying the gate defines zero volts between G and S and the FET should be off and read open circuit.
If the FET is good and you don't tie the gate then you will find that just dabbing a finger on the gate will tend to either turn on or turn off the FET as you charge the gate capacitance up. It will stay in that state for hours until you touch it again. Tying the gate defines zero volts between G and S and the FET should be off and read open circuit.