Use some separator other than a -. It's confusing in some instances where it could be taken for negative.
Was the 10v reading from the negative side drivers?
If so, why aren't you getting the full 12v to the driver pair?
Was the 10v reading from the negative side drivers?
If so, why aren't you getting the full 12v to the driver pair?
i installed 2 fets per side but they heat up immediately.
the pulldown resistor is 100k, when in circuit it measures 20k, is this correct?
Gate resistors are 10ohm
the pulldown resistor is 100k, when in circuit it measures 20k, is this correct?
Gate resistors are 10ohm
Did the amplitude of the low-side increase?
20k is correct if there are 5 of them on that side. 100k/5 = 20k.
Can you see what frequency they're oscillating at before they overheat (clamp them if necessary to prevent overheating)? Before, they were seeing a signal of about 100Hz (whatever you were driving into it). Are they now oscillating near 80kHz?
20k is correct if there are 5 of them on that side. 100k/5 = 20k.
Can you see what frequency they're oscillating at before they overheat (clamp them if necessary to prevent overheating)? Before, they were seeing a signal of about 100Hz (whatever you were driving into it). Are they now oscillating near 80kHz?
no it didn't... just thought i could try the fets.
upon further investigation the 7912 is outputting 14.5v, after replacing it still similar voltage
upon further investigation the 7912 is outputting 14.5v, after replacing it still similar voltage
I traced the voltage from the drive transistors collectors to the 7812 and 7912.
7812 : 12.2V
7912 : -14.5v
I assume this is why the amplitude is not the same?
7812 : 12.2V
7912 : -14.5v
I assume this is why the amplitude is not the same?
Measuring the DC across the following components, is there a difference between the voltages? Do this without an input signal.
D1 compared to D9?
R22 compared to R29?
R20 compared to R5?
D1 compared to D9?
R22 compared to R29?
R20 compared to R5?
If you drive a signal into the amp, do you get a symmetrical waveform (equal above and below ground) on the output of the LM211 and on the bases of Q7/11?
Q7 and 11 pull up/down from the rails. Do you see about the same amplitude of signal on the collectors of each transistor? This will be the same signal as on the base of the driver transistors.
The signal on the emitter of the drivers should be very nearly the same.
The signal on the emitter of the drivers should be very nearly the same.
Touch your scope probe to the negative rail and make a note of precisely where it deflects the trace. Then probe the emitters of the drivers for the low side. Is the problem that the drive signal isn't going back fully to the rail or is it that it's not driving far enough from the rail?
Do the same on the high-side.
Do the same on the high-side.
I'm not sure i follow Perry, the drive signal is present on all the pads, its just the amplitude that's the issue.
the high side has an higher amplitude than the low side.
voltage high side gate to source is 7.6v and low side is 3.8v
the high side has an higher amplitude than the low side.
voltage high side gate to source is 7.6v and low side is 3.8v
no they are out of circuit, I tried a pair each, my supplier gave me irf640n, instead of the 640. they started to heat up very quickly.
What did you mean by:
the drive signal is present on all the pads
Which transistors are you referring to?
the drive signal is present on all the pads
Which transistors are you referring to?