Amp powers up fine and idles with D6 removed, that feeds the protection circuit on the p.s. driver board. I have a 40Hz signal fed into the amp and see a 40Hz square wave on the base of the inverter/voltage amplifier transistors(D1820_V51 driver board). The collector is sitting at rail. Those parts have been replaced along with the 470 ohm resistors that were out of tolerance.
I'm missing the high frequency carrier?
I'm missing the high frequency carrier?
Did you check the 1D and 2D transistors to confirm that none were leaking and that all had 2 good junctions?
Don't forget to check ALL of the gate drive signals. These amps will operate even when some of the outputs aren't being driven. This will lead to premature failure of the outputs that are being driven.
Don't forget to check ALL of the gate drive signals. These amps will operate even when some of the outputs aren't being driven. This will lead to premature failure of the outputs that are being driven.
When the class D stage isn't oscillating, you will see the audio drive frequency as a square wave on the output transistors. I don't know what D6 does in that amp. You may have to reinstall it and disable the protection circuit in another way to see if it will try to oscillate. If you see excessive DC or excessive current draw, it will show you what type of fault you have and make it easier to troubleshoot.
Reference the aq2200 schematic, pwm section IC2 pin 1 is sitting at 7 volts. I lifted D206 (upper right corner) Pin 1 stayed at 7 volts. I then lifted D9(attached to pin 1). The supply will operate and no excessive current draw, but I have no oscillation on the output.
Is there a mute circuit in this amp? It's like the American Bass XD series.
Is there a mute circuit in this amp? It's like the American Bass XD series.
Pin 3 is high on IC2, which indicates an over-current issue, but I check the readings on U1 of the driver board and those don't indicate one.
IC2
1) 12.991
2) 2.488
3) 11.8
4) 0
5) 1.068
6) 3.56
7) 0.172
8) 13.0
U1 (LM293)Driver board measurements reference -rail
1) 2.08
2) 1.342
3) 1.489
4) 0
5) 7.67
6) 1.428
7) 1.342
8) 15.69
IC2
1) 12.991
2) 2.488
3) 11.8
4) 0
5) 1.068
6) 3.56
7) 0.172
8) 13.0
U1 (LM293)Driver board measurements reference -rail
1) 2.08
2) 1.342
3) 1.489
4) 0
5) 7.67
6) 1.428
7) 1.342
8) 15.69
Email me. I have a similar diagram that may be closer to what you have. If we can get an exact match, it will make things easier.
babin_perry@yahoo.com
babin_perry@yahoo.com
I don't know. This is why I hate self-oscillating amplifiers. Any break or defective circuit can cause the output stage to fail to oscillate. Without a schematic diagram for the driver board, you're likely going to have to check every component.
Did you confirm that you have 12v across the 12v zeners on the driver board?
Did you confirm that you have 12v across the 12v zeners on the driver board?
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