When you refer to IC9, do you mean to say Pins 4 & 8?
If there is a short across IC9, the voltage you measured across ZD5 would be near zero, not the 12.67 volts you stated in post #34. IC9 is supplied by the combination ZD4-24v(your measurement is .786 volts) and ZD5-12v. You should see 36 volts between Pin 8 & Pin 4, instead your seeing 13.456 volts, which is nearly a third of the proper operating voltage.
The measured voltage across ZD3 in your post #34 is 2.267 volts not the 12 volts you should see. ZD4 measuring .786 volts is in series with ZD3. The addition of ZD4 and ZD3 = 3.053 volts, again well below the proper operating voltage for the IC's. The zener diode ladder supply ZD3,ZD4,ZD5 are all in series and supply IC9,IC10,IC11 and they are in effect the heart of the class D amp.
Because ZD3 and ZD4 are abnormally low means that C61-100nf is bad. Even though C61 reads 100nf with your capacitance's meter doesn't mean it will fail in circuit. I have seen this failure many times!! I'm very confidant this will fix this problem, there may be other issues, but you should replace C61. I would also replace C62 and C63, all 100nf.
C60 is a .1uf Capacitor. Replace this cap with an NPO specification. This is the circuit that generates the PWM and this capacitors is a critical part.
If there is a short across IC9, the voltage you measured across ZD5 would be near zero, not the 12.67 volts you stated in post #34. IC9 is supplied by the combination ZD4-24v(your measurement is .786 volts) and ZD5-12v. You should see 36 volts between Pin 8 & Pin 4, instead your seeing 13.456 volts, which is nearly a third of the proper operating voltage.
The measured voltage across ZD3 in your post #34 is 2.267 volts not the 12 volts you should see. ZD4 measuring .786 volts is in series with ZD3. The addition of ZD4 and ZD3 = 3.053 volts, again well below the proper operating voltage for the IC's. The zener diode ladder supply ZD3,ZD4,ZD5 are all in series and supply IC9,IC10,IC11 and they are in effect the heart of the class D amp.
Because ZD3 and ZD4 are abnormally low means that C61-100nf is bad. Even though C61 reads 100nf with your capacitance's meter doesn't mean it will fail in circuit. I have seen this failure many times!! I'm very confidant this will fix this problem, there may be other issues, but you should replace C61. I would also replace C62 and C63, all 100nf.
C60 is a .1uf Capacitor. Replace this cap with an NPO specification. This is the circuit that generates the PWM and this capacitors is a critical part.
100nf 100v caps came in today. I replaced the three. C61-63. As for c60 .1uf is 100nf correct? After replacing the three voltages remain the same.
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Changed ic10 and now I have
Zd3: 12.29vdc
Zd4: 26.17vdc
Zd5:. 12.4vdc
Zd7: 10.88vd
Missing the drive signal on pin 7 still.
Zd3: 12.29vdc
Zd4: 26.17vdc
Zd5:. 12.4vdc
Zd7: 10.88vd
Missing the drive signal on pin 7 still.
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If you remove IC10, what are the voltages across ZD3 & ZD4?
Ignore my question, I missed your post #45
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Okay, so the ladder circuit is restored, IC 10 was shorted between PIn 4 and Pin 8.Good Call!
Remind me which capacitor you grounded?
Pin 7 on IC11? The op amp associated with Pin 7 may be collateral damage. Try changing it and see what happens,
Remind me which capacitor you grounded?
Pin 7 on IC11? The op amp associated with Pin 7 may be collateral damage. Try changing it and see what happens,
I cahnged the tl072 ic9. It didn't change anything still nothing on pin 7 I also changed the cap .1uf c60. I still don't have that drive on pin 7?
Without power applied measure with an ohmmeter from Pin 7 and then Pin 1 of IC11-LM393 and the Power Ground Terminal. Post what you find.
It's possible that IC11 has failed. The output of Pin 7 IC11 feeds the input of Pin 3 IC14-IRS20957.
D103-BAT54C is connected between Pin 3 IC14/PIN 7 IC11 and Power Ground.
You may find that one or all three need to be replaced.
It's possible that IC11 has failed. The output of Pin 7 IC11 feeds the input of Pin 3 IC14-IRS20957.
D103-BAT54C is connected between Pin 3 IC14/PIN 7 IC11 and Power Ground.
You may find that one or all three need to be replaced.
That did it bill the 393 was bad. I replaced it and the pin 7 signal came back for a moment and now it is gone again.
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From main ground to pin 1 157.9ohms
Pin 2 160.8ohms. did you want the resistance between pin 1 and pin 7?
Pin 2 160.8ohms. did you want the resistance between pin 1 and pin 7?
When you say Pin to are you referring to Pin 7?
You may want to replace IC14-IRS20957 and maybe D103- BAT54C.
I'm a bit stomped. The power supply works, The PWM works, You have Drive out of IC11 Pin 1 but not Pin 7.
There may be something in the in the output on the IC14 side, that's dragging down the drive. If replacing IC14 you still don't have drive, take a close look at the outputs for shorted output devices or broken leads, traces,bad solder joints, open gate resistors, bad gate drivers.
You may want to replace IC14-IRS20957 and maybe D103- BAT54C.
I'm a bit stomped. The power supply works, The PWM works, You have Drive out of IC11 Pin 1 but not Pin 7.
There may be something in the in the output on the IC14 side, that's dragging down the drive. If replacing IC14 you still don't have drive, take a close look at the outputs for shorted output devices or broken leads, traces,bad solder joints, open gate resistors, bad gate drivers.
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