Hifonics BXI 2610D

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Hello I have a BXI2610D amplifier and the driver transistors went out causing the IRFP064N mosfets to blow in the power supply. I replaced the drivers with NTE 31 and NTE 32. Then I replaced the mosfets. The amp worked fine for a while and then the same issue occured. Could the PWM circuit be failing causing the rest of my problems to reoccur? I would like to fix this amp once and for all being as its a great amp. Any input would be greatly appreciated. Thanks.
In my honest opinion. Never use NTE parts in amps they are usually expensive and alot of amps do not like NTE parts..

When you order the power supply fets also order BD139's and BD140's for replacements for the drivers.. Ive used them in alot of amps and so has Perry and never had a problem with them.

Also before u order the parts make sure u also check the gate resistors for the power supply fets and make sure they are within tolorance..
Thanks mike. I already picked up the NTE parts at a local parts store but i will return them to get the ones you stated. I haven't checked the gate resistors but will do so. Can you tell me what value they should be? I don't have an oscilloscope yet so i have to get one of those too. I want to make sure the waveform coming from the drivers is correct before putting in all of the FETs. Thanks again. Im just learning electronics so this is my first project and it was fixed once so i know i can do it again :)
I have all the fets removed and got the BD 139 and BD 140 drivers in place. The voltage at each gate pad reads +4.15 and -8.8 volts. Is this correct? I will post pics of the waveform by the weekend if I can get a scope. Also should the zener diodes at each end of the mosfet banks be replaced? Not sure if they are good but i didn't replace them last time and the amp worked flawlessly until the power supply melted down again.
They are between the toroid transformers. The white wire is ground that burned a trace going to the PWM board and the driver transistors. I believe it was due to the drivers shorting out. Correct me if I'm wrong though.


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Yes with positive lead of DVM hooked to B+ and Black lead touching the Gate pads of the fets there was 8.8 volts. With the black lead hooked to ground there was 4.15 volts. Not sure if this is supposed to be but a waveform would definately clear up any confusion. Will get that posted asap.
Black probe on ground and red on gate pads showed 4.15 volts. I also only removed the fets that showed signs of damage: blackened and cracked which was only on one side of the amplifier's power supply. The other side's fets all had a shorted gate but appeared fine. This gave the other side of the fets ground causing the meltdown. The drivers may have been fine but i replaced them anyways. Now I put two good fets back on one side of the amp and it powers up and i get 73 vdc on the output rail. Now to just put all new fets in and we're good to go. Where can I get genuine IRFP064N that are from one batch and not from china. The previous one were chinese which is probably why my repair failed again. This is a well designed amp but cheap components are my downfall at this point. Thank you guys for all the help. I really appreciate it. Im only 19 so im still learning electronics but its my favorite hobby of anything :)
Well They all checked out to be within tolerance at 46.5 to 47 ohms and I am getting 4.15 volts at each gate. Is the -8 volts I was getting with positive lead on the B+ terminal and the black test lead on each gate pad used to turn the mosfets "off"? I know the rising edge of the wave turns them on and the falling edge turns them back off correct?
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