It's rare that the FETs don't drive rail voltage back into the ICs, destroying them.
It takes only about 5 minutes to replace two ICs, less for one.
If you're going to repair it for a very low price and tell the owner that there is no warranty, I might let it go without replacing the ICs (after thorough testing).
It takes only about 5 minutes to replace two ICs, less for one.
If you're going to repair it for a very low price and tell the owner that there is no warranty, I might let it go without replacing the ICs (after thorough testing).
I received this amp again. One fet on the Highside is shorted. The ICs still working fine, cant find any problems. Only, this is the second amp from him, where the Cap for RCA ground is exploded. I tould him, to check his cables. He tould me, that he has sometimes a loud bump from the radio...
I dont know, if this can affect, the outputs to be damaged.
See the pictures. Maybe somebody can give an advice.
The mosfets stay cold after running about 3 Minutes without heatsink, and only one fet per bank.
The Cap is Position C112B.
The Osci is connected between gate and source
I dont know, if this can affect, the outputs to be damaged.
See the pictures. Maybe somebody can give an advice.
The mosfets stay cold after running about 3 Minutes without heatsink, and only one fet per bank.
The Cap is Position C112B.
The Osci is connected between gate and source
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So, nothing happend. Heated up to about 40 degre C. So its hot, that i just can touch the inductors. Twisted again, nothing happen. Only the current during heat up dropped a little bit. 0,1Amps. Output is also clean... I still think, that something with his cables is not ok. Also i never seen before, that the caps on the rca are exploded... Maybe this has something to do with it.
So, received the amp back, this time with burned PS, and one Fet in the Audio burnt. The drive board for audio should be ok, because there is a drive stage between fets and board.
Removed all fets, and driver transistors for PS, Signal from TL is good. Anyway the relay is clicking without all this parts. So it could be, that the mute circuit is damaged to, because i think it should only engage after rail is full up?
Removed all fets, and driver transistors for PS, Signal from TL is good. Anyway the relay is clicking without all this parts. So it could be, that the mute circuit is damaged to, because i think it should only engage after rail is full up?
Relay SHOULD be clicking even without the driver board in. It's tied to the power supply section and not to the amplifier section. I've repaired a lot of these amps. I do have the schematic if You need it.
If there is shorted output transistor, almost 100% the class driver board DWM 3640 is damaged too. Usually the IRS21844s are the ones that dies fairly easy.
There is NO buffer transistor between the driver board and the output transistor.
I've rarely ever seen problems with the mute transistor or the preamp section.
If there is shorted output transistor, almost 100% the class driver board DWM 3640 is damaged too. Usually the IRS21844s are the ones that dies fairly easy.
There is NO buffer transistor between the driver board and the output transistor.
I've rarely ever seen problems with the mute transistor or the preamp section.
Hello, thank you for reply. I think I must have older version of this amp with buffer stage. See picture attached. Also it has FDA59n25 fets in the output. Maybe you can supply me with the diagram, because in the beginning, I had, that randomly one or to output fets are blown.
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