the high side driver parts will all be ruined when the output fets die.
when a D amp dies, all the drivers and sometimes the comparator get killed as well. the high side supply diode may have died as well. this is connected to the low side power supply and capacitor that is connected to the output before the coil.
when a D amp dies, all the drivers and sometimes the comparator get killed as well. the high side supply diode may have died as well. this is connected to the low side power supply and capacitor that is connected to the output before the coil.
So, a whole new batch of IRF640N arrived.
I removed the 640N's which were installed and replaced it with the all new IRF640N (1 fet per bank, same batch number).
Fets get killed.....
This makes no sense.....
I removed the 640N's which were installed and replaced it with the all new IRF640N (1 fet per bank, same batch number).
Fets get killed.....
This makes no sense.....
Try again with the limiters in series with the inductors.
If it powers up without blowing the FETs, check the waveforms on each end of the limiters. Are they virtually identical?
If it powers up without blowing the FETs, check the waveforms on each end of the limiters. Are they virtually identical?
So if I undertand correctly...you had a working amp with one mosfet in each bank, in total 4 mosfets. Then you changed them with 4 new mosfets and they blow..?
Correct.
It makes no sense to me.
I double checked every solder connection from the IRF640N's, also used my multimeter to check if they had a solid connection.
Also checked the gate drive before fitting the new fets.
It makes no sense to me.
I double checked every solder connection from the IRF640N's, also used my multimeter to check if they had a solid connection.
Also checked the gate drive before fitting the new fets.
I guess something in the output filtering goes wrong, intermittent. Check dubble check the output inductors. (How many uH are they..?)
Or a gate-resistor is bad, or bad soldering, had one board with issues like this. They can be very simple to repair...or a real pita. Is this a blue board?
Or a gate-resistor is bad, or bad soldering, had one board with issues like this. They can be very simple to repair...or a real pita. Is this a blue board?
Yes! this is a blue board 🙂
I'm very happy you say this hehe. Then I'm not the only person experiencing this problem.
Terrible soldering done on these boards, with very bad vias. Seems like the traces have some kind of slightly corroded top layers which makes it hard to solder sometimes. I scratched all the top layers with a sculpting knife to make sure it made a good contact. Used a lot of Flux and 99.9% isopropyl to clean afterwards.
For so far I can remember me (I can measure again later this week), the output inductors rode 40uH per inductor.
Gate resistors are all good.
I don't really know what to do with this amplifier. The whole output drive circuit has been killed again because of the blown fets, which makes it the 6th time.
Changed the 74HC00 from the main driver board and the 2x, 2T transistors connected to the output of the main driver board.
Unfortunately the main driver board is not creating a PWM output drive. Seems like there is a clean triangle wave present on an other (masked) IC from the main driver board, but between that and the 74HC00 goes something wrong.
Currently there is a tinny square wave present on the output pins of the main driver board which has the drive frequency of the PS fets o_0
Not sure if this amplifier is reliable and thrustable anymore.
What do you guys think?
You guys are way more knowlegded then me 😀
I'm very happy you say this hehe. Then I'm not the only person experiencing this problem.
Terrible soldering done on these boards, with very bad vias. Seems like the traces have some kind of slightly corroded top layers which makes it hard to solder sometimes. I scratched all the top layers with a sculpting knife to make sure it made a good contact. Used a lot of Flux and 99.9% isopropyl to clean afterwards.
For so far I can remember me (I can measure again later this week), the output inductors rode 40uH per inductor.
Gate resistors are all good.
I don't really know what to do with this amplifier. The whole output drive circuit has been killed again because of the blown fets, which makes it the 6th time.
Changed the 74HC00 from the main driver board and the 2x, 2T transistors connected to the output of the main driver board.
Unfortunately the main driver board is not creating a PWM output drive. Seems like there is a clean triangle wave present on an other (masked) IC from the main driver board, but between that and the 74HC00 goes something wrong.
Currently there is a tinny square wave present on the output pins of the main driver board which has the drive frequency of the PS fets o_0
Not sure if this amplifier is reliable and thrustable anymore.
What do you guys think?
You guys are way more knowlegded then me 😀
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I did many of these amps, or alike, but not this bad damaged. Never had the PWM driverboard defect, always the driverboards with the 6N137 opto's (changed complete driverboards) , IRF640N, gate resistors..
So maybe a had more luck than you have with them and some of them came back after few weeks, blown again or went in protection without any reason. I tested them on 1 ohm, for many hours. Use always the same test method for repaired amps and these are not very relaible.
So I have not a simple solution available, you did rebuild both the 6n137 driveboards I think?
So maybe a had more luck than you have with them and some of them came back after few weeks, blown again or went in protection without any reason. I tested them on 1 ohm, for many hours. Use always the same test method for repaired amps and these are not very relaible.
So I have not a simple solution available, you did rebuild both the 6n137 driveboards I think?