It looking same like fet gate. Both pnp has same waveform on its base.
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Gate of fet = 94.7kohms all fet gates same.
Pin 9/ 10 = 0.983kohms
Emitter of pnp = 94.6kohms both pnp same
I added 510ohms on emitter to collector the current pull reduces from 1.6amp to 1amp but still all the fets getting hot in few seconds.
Yes all the fets in place. Both side fets of both banks getting hot. Current keep increasing as they gets hot.
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You'll need to power up through a limiter, initially, for the following. This assumes that there is a resistor (10k?) between pin 4 and ground at this time.
On the 494, connect a 510 ohm resistor between pins 4 and 7. Connect a 10k resistor between pin 14 and 4.
Do the FETs heat up through the limiter?
If all seems to be OK, power up without the limiter to see if the idle current has changed.
On the 494, connect a 510 ohm resistor between pins 4 and 7. Connect a 10k resistor between pin 14 and 4.
Do the FETs heat up through the limiter?
If all seems to be OK, power up without the limiter to see if the idle current has changed.
Yes idle current is now only 0.4ohms. So what is all this problem is about? No fets seems to be hot again.
It appears that the drivers cannot pull down the gates of all of the FETs efficiently.
What you did was increase the deadtime. The voltage divider formed by the 510 and 10k resistors set the voltage on pin 4 slightly above 0v. If you use this as a solution, the resistors chosen need to be able to get the voltage on pin 4 to just slightly above the point where the current draw drops off.
If you're going to remove the resistors between the collector and emitter of the driver, remove them, then adjust the deadtime to the final value.
What you did was increase the deadtime. The voltage divider formed by the 510 and 10k resistors set the voltage on pin 4 slightly above 0v. If you use this as a solution, the resistors chosen need to be able to get the voltage on pin 4 to just slightly above the point where the current draw drops off.
If you're going to remove the resistors between the collector and emitter of the driver, remove them, then adjust the deadtime to the final value.
I removed the resistors from drivers emitter and collector. And tried with the same 510ohms and 10kohms divider and it idling on 0.4ohms. So I will leave it just so. Voltage on pin4 is only 0.2v. Also when i got the amp the rail capacitors of one bank were bulged. I changed them.
If you're using the 3205s, I'd leave the 47s. If everything is working properly, there's no point in changing anything.
What'a the duty cycle at the output of the 494? Post an image of both pins 9 and 10 at the same time (two probes, two channels of the scope). I'd like to see that the 0.2v isn't pulling the duty cycle back too far.
What'a the duty cycle at the output of the 494? Post an image of both pins 9 and 10 at the same time (two probes, two channels of the scope). I'd like to see that the 0.2v isn't pulling the duty cycle back too far.
it was using IRFZ44N. amp blew power supply fets. again gate frequency gone high. and right now no mosfets and no rectifiers and TL494 alone oscillating at 63khz and i changed to TL595 and it is oscillating about 300khz. dont know whats going on with this amplifier. something must be bad which i am not seeing.
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