Hi Perry!
Ich checked both resistors in circuit,
R28 = 238,4 ohms, Voltages: -35.8V and -31.2V
R26 = 2360 ohms; Voltages: -35.8V and -3,26V
Across the output channel i have: - 24.3V of DC
I thought checking the resistors in circuit was ok.
Should i better remove them and check again?
Thank you very much for your time 👍
Ich checked both resistors in circuit,
R28 = 238,4 ohms, Voltages: -35.8V and -31.2V
R26 = 2360 ohms; Voltages: -35.8V and -3,26V
Across the output channel i have: - 24.3V of DC
I thought checking the resistors in circuit was ok.
Should i better remove them and check again?
Thank you very much for your time 👍
cathode: 490mV
Anode: -3.25V
I changed the diode before i got the schematics and now i see that a 1N4003 is used.
I soldered 1N4004 into the board.
Sorry, i forgot that
Anode: -3.25V
I changed the diode before i got the schematics and now i see that a 1N4003 is used.
I soldered 1N4004 into the board.
Sorry, i forgot that
The 4004 isn't a problem.
Ground the RCA shield.
Repost the voltage on the regulator terminals.
Did you check the 1k resistor, R32? If not, do so now.
Ground the RCA shield.
Repost the voltage on the regulator terminals.
Did you check the 1k resistor, R32? If not, do so now.
With grounded RCA shields i have almost the same voltages like in Post #19:
1: -35.9V
2: -36.8V
3: -31.1V
I already checked R32, its ok
1: -35.9V
2: -36.8V
3: -31.1V
I already checked R32, its ok
I bought them locally and paid more than online. In our country the supplier is a trusted one.
I have two different types of them from different manufacturers, i will try the other one and report.
I have two different types of them from different manufacturers, i will try the other one and report.
Wow!
I reconnected the old one and now i have +- 13 volts DC on the opamps!! I put those regulators into the trashcan.
Even without the bridge Shield to GND.
But there are still 24.5 V on the speaker terminal.
Q17 is still lifted.
The old regulator is LM337SP and i had LM337T
I was wrong, the LM317 were bought from my local shop. I ordered the 337 online, that was a mistake 😢
I reconnected the old one and now i have +- 13 volts DC on the opamps!! I put those regulators into the trashcan.
Even without the bridge Shield to GND.
But there are still 24.5 V on the speaker terminal.
Q17 is still lifted.
The old regulator is LM337SP and i had LM337T
I was wrong, the LM317 were bought from my local shop. I ordered the 337 online, that was a mistake 😢
No , i only changed the source resistors
and i couldnt find a dead FET.
Idle is 0.4 amps at the moment.
and i couldnt find a dead FET.
Idle is 0.4 amps at the moment.
Did you check between all 3 terminals in all configurations of meter probe to FET terminal?
If you briefly touch a load across the speaker terminals, does the DC immediately drain off or does it cause the amp to draw additional current?
If you briefly touch a load across the speaker terminals, does the DC immediately drain off or does it cause the amp to draw additional current?
I checked them in all pin configurations and didnt find a shorted one.
If i load the output with a 4ohm speaker, the speaker pops out and the amp tries to pull a lot more amps.
If i load the output with a 4ohm speaker, the speaker pops out and the amp tries to pull a lot more amps.
I am a little confused - the -24VDC on the outputs is gone. but i dont know why.
i had a gate resistor R197 which was out of tolerance- a new one measured 9.99 ohms and R197 was 9.6 ohms.
After changing that resistor i still had DC. So i measured around C126, C127 and C128 but i didnt change something.
But DC is gone now. i soldered Q17 back in place and amp is working, now it is possible to adjust the idle current .
Thank you for all your help, its a little frustrating that i dont know why the amp is working again. Can the difference of 0.4 ohms of the gate resistor
cause the problem?
Or a bad solder-connection of the SMD caps?
Best regards!
Andi
i had a gate resistor R197 which was out of tolerance- a new one measured 9.99 ohms and R197 was 9.6 ohms.
After changing that resistor i still had DC. So i measured around C126, C127 and C128 but i didnt change something.
But DC is gone now. i soldered Q17 back in place and amp is working, now it is possible to adjust the idle current .
Thank you for all your help, its a little frustrating that i dont know why the amp is working again. Can the difference of 0.4 ohms of the gate resistor
cause the problem?
Or a bad solder-connection of the SMD caps?
Best regards!
Andi
Those aren't likely to cause the problem. What may have happened was the DC was present but not driven to the speaker terminal. It wasn't pulled down because the output stage was disabled. The test with touching the load was to determine if the DC was driven there or simply present and insignificant.