In this particular amp, im having DC voltage on the output of this amp. The four IRF640 behind the rotary controls (not the input jack side) is getting hot.
Ive removed the riser board and ive checked all the components that drives the gate signals for the output fets.
Ill post up a pic of the amp shortly.
Ive removed the riser board and ive checked all the components that drives the gate signals for the output fets.
Ill post up a pic of the amp shortly.
Remove the rectifiers (AFTER discharging the rail caps). Then you can check the drive signals on the FETs. Without the rectifiers, you can connect your scope ground to the source legs of the FETs and see the signal clearly with the FETs in the circuit. If there is any problem with the drive signal, it should be obvious.
Should I also put in back the driver board? As I'm having the heating issue with ans
Without it in the circuit.
I obviously won't get power to the output and the frontend stages of the amp, will I see a signal on the oscilloscope?
And why is it when I use the ground reference on the speaker ground(torrodial center tap secondary) I'm seeing large voltages around the pins and tab of the 5volt regulator (7805) unlike the other bank the tab is ground and there is 12volts and 5volts respectively.
Without it in the circuit.
I obviously won't get power to the output and the frontend stages of the amp, will I see a signal on the oscilloscope?
And why is it when I use the ground reference on the speaker ground(torrodial center tap secondary) I'm seeing large voltages around the pins and tab of the 5volt regulator (7805) unlike the other bank the tab is ground and there is 12volts and 5volts respectively.
Without the rectifiers, you will have everything except the high rail voltage. Without the rectifiers, you can use leg 3 of the FET for the reference so that you can see the exact drive signal.
You will have to reinstall the driver board.
You will have to reinstall the driver board.
All 4 center tap rectifier is pulled and both bank of fets has voltage across gate and source legs same as I show you on the pic of the scope.
In reference to ground I don't see any waveform. On the same riser card however I've noticed one of the 74HC02D gets extremely hot, the bottom one U704.
It's either driving a shorted component or defective. Could there be a solder bridge between adjacent pins on the driver board?
The driver board hasn't been repaired before its only been removed and reinsert on the main board. There's no solder blob or any short.
My question Sir Babin, if the driver board is removed should it still flicker the power led while on protect (just the same as when it's in and the rectifier is in place)?
My question Sir Babin, if the driver board is removed should it still flicker the power led while on protect (just the same as when it's in and the rectifier is in place)?
I don't remember the LED flashing when I've done this. Short the positive and negative speaker terminals to see if that makes a difference.
Sometimes you can get tiny strands of solder (especially with chipquik) between the pins on the driver board when it's being removed. You can check with a meter to see if you have shorted pins.
Sometimes you can get tiny strands of solder (especially with chipquik) between the pins on the driver board when it's being removed. You can check with a meter to see if you have shorted pins.
I'm on the work bench with it, just triple checked it and no short. Be inform that it only won't start when I add the rectifiers and it does this even without the driver board. Any other ideas based on your expertise?
Do you see a square wave from the last 2 pins on the driver board?
Do you have any waveforms on the LM219 now?
If the hc02 heating?
Have you confirmed that all 3 of the 5v regulators are producing 5v out?
Do you have any waveforms on the LM219 now?
If the hc02 heating?
Have you confirmed that all 3 of the 5v regulators are producing 5v out?
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