No everything was original .
I went back through the circuit and found D104 (H5) shorted as well .
Do you happen to know what diode H5 is ?
I went back through the circuit and found D104 (H5) shorted as well .
Do you happen to know what diode H5 is ?
H5 means it's a 15v Zener.
When anything fails in these regulators, you can expect everything to fail.
The only diode that I've seen in that location (across the cap) was a Zener. I think it was a 18v but could have been a 20v. It makes no sense to have a standard diode connected like it was.
When anything fails in these regulators, you can expect everything to fail.
The only diode that I've seen in that location (across the cap) was a Zener. I think it was a 18v but could have been a 20v. It makes no sense to have a standard diode connected like it was.
Install it and post the DC voltage on all 3 legs of all of the SMD transistors.
Leave the FET out of the circuit.
Leave the FET out of the circuit.
Q107
Base:83.5
Emitter:84.1
Collector :17.9
Q106
Base:14.7
Emitter:14.2
Collector :84.1
Q110
Base:14.7
Emitter:14.1
Collector:83.5
This is with the fet in circuit .
I installled it before I read your post
Base:83.5
Emitter:84.1
Collector :17.9
Q106
Base:14.7
Emitter:14.2
Collector :84.1
Q110
Base:14.7
Emitter:14.1
Collector:83.5
This is with the fet in circuit .
I installled it before I read your post
I’m assuming the 15 volt zener that was bad was causing the problem .
I replaced the fet , the cap, the 15 volt zener and all the transistors
I replaced the fet , the cap, the 15 volt zener and all the transistors
The (Zener) diode that was on the output of the regulator helps to protect the op-amps all over the amp when the regulator fails. It's up to you whether you leave the 1N4001 or replace it. The 4001 offers no protection.
If the regulator failed with the preamp board connected, expect there to be, at least, several failed 10 ohm resistors.
If the regulator failed with the preamp board connected, expect there to be, at least, several failed 10 ohm resistors.
I checked all of the 10 ohm resistors on the preamp board and all test fine .
Which is weird since this is the only 1 that I’ve seen not blow the resistors on the preamp board .
I installed the 1 ohm resistors and will get the right diode and test the amp for output
Which is weird since this is the only 1 that I’ve seen not blow the resistors on the preamp board .
I installed the 1 ohm resistors and will get the right diode and test the amp for output
Replaced the cap and diode .
Now I have -84 volts measured directly across speaker terminals .
Possibly a bad optocoupler?
Wondering where i go from here
Now I have -84 volts measured directly across speaker terminals .
Possibly a bad optocoupler?
Wondering where i go from here
What is the DC voltage on each of the optocouplers (black probe on pin 5, red on 8)?
What is the DC voltage on the supply terminals of the op-amps near the optocouplers?
What is the DC voltage on the supply terminals of the op-amps near the optocouplers?
A3120:17.79
A3120:15.81
Pin 1:-14.56
Pin 2:-14.05
Pin 3:-14.28
Pin 4:-15.13
Pin 5:-13.33
Pin 6:-13.21
Pin 7:-8.62
Pin 8:14.80
Pin 1:-3.03
Pin 2:-4.20
Pin 3:-4.03
Pin 4:-15.17
Pin 5:-2.84
Pin 6:-2.14
Pin 7:-3.01
Pin 8:14.82
A3120:15.81
Pin 1:-14.56
Pin 2:-14.05
Pin 3:-14.28
Pin 4:-15.13
Pin 5:-13.33
Pin 6:-13.21
Pin 7:-8.62
Pin 8:14.80
Pin 1:-3.03
Pin 2:-4.20
Pin 3:-4.03
Pin 4:-15.17
Pin 5:-2.84
Pin 6:-2.14
Pin 7:-3.01
Pin 8:14.82
Do you have a pic of the area around the opamps ?
I didn’t pay attention and not sure if I pulled a resistor off the bird or not . R415 is in question .
I didn’t pay attention and not sure if I pulled a resistor off the bird or not . R415 is in question .