Measuring the DC voltage across the Zeners is pointless unless the resistors are being fed with voltage from the supply, which would make them heat up.
Q504 must be in the circuit.
From the voltages, I don't think they will engage. Is E502 leaking or shorted? If you're not sure, remove it and re-check the voltage on Q504 with Q503 out of the circuit.
Q504 must be in the circuit.
From the voltages, I don't think they will engage. Is E502 leaking or shorted? If you're not sure, remove it and re-check the voltage on Q504 with Q503 out of the circuit.
q504 reinstalled with q503 out of the circuit. relays do not activate.
q504= b=190mV c=8.5V e=190mV
E502 is new. I know that doesnt mean too much these days. E502 is currently not in the circuit.
considering the heat coming from the resistors, I would assume they are getting voltage?
q504= b=190mV c=8.5V e=190mV
E502 is new. I know that doesnt mean too much these days. E502 is currently not in the circuit.
considering the heat coming from the resistors, I would assume they are getting voltage?
Is R501 within tolerance.
I'm not confident on whether the supply is constantly operating. At one time you stated that the amp was drawing 3A and other times about 0.2 amps. Is the amp constantly drawing 3 amps when you have the amp powered up?
I'm not confident on whether the supply is constantly operating. At one time you stated that the amp was drawing 3A and other times about 0.2 amps. Is the amp constantly drawing 3 amps when you have the amp powered up?
r501 is reading 74.1k ohm in situ, so that seems within spec. I should note, this area of the board was pretty bad and I replaced r501, r502, r532, and r531 with new resistors.
as far as the current draw from the power supply, it seems that there is some sort of time that needs to happen now for the status light to turn green from orange. prior to jumpering the ground we did the other day to the inner speaker terminals, it would go green within a few seconds and the mute led would turn yellow. since the jumpering, the mute led is always orange now and the status light seems to turn green after voltage has been applied to the amp for a little bit of time. after that, all testing has been done with green status light and 3A draw from the power supply.
as far as the current draw from the power supply, it seems that there is some sort of time that needs to happen now for the status light to turn green from orange. prior to jumpering the ground we did the other day to the inner speaker terminals, it would go green within a few seconds and the mute led would turn yellow. since the jumpering, the mute led is always orange now and the status light seems to turn green after voltage has been applied to the amp for a little bit of time. after that, all testing has been done with green status light and 3A draw from the power supply.
Did you confirm that both power supplies are running?
What's the resistance from the base of Q504 to the emitter of Q504?
Without Q503 in the circuit, R501 should be pulling the base up.
What's the resistance from the base of Q504 to the emitter of Q504?
Without Q503 in the circuit, R501 should be pulling the base up.
on of the first things I did was set the voltage at the rails per the service manual and they were all set to spec when I last checked.
resistance between q504 and emitter of q504 is about 10k ohm. I did not test this with the amp powered up. e502 is still removed as is q503.
resistance between q504 and emitter of q504 is about 10k ohm. I did not test this with the amp powered up. e502 is still removed as is q503.
Do you read 0 ohms between R501 and R502?
Between R502 and the base of Q504?
What made this part of the board so bad?
Between R502 and the base of Q504?
What made this part of the board so bad?
I have continuity between r501 and r502. It appears to be around maybe an ohm.
R502 to base of q504 appears to be 3M ohm.
I'm not really sure the cause of all of this. I purchased it knowing it had a non functioning status and was hoping to recap it and have a nice amp combined with doing a bit of learning along the way. The resistors in that area were very black as was the board. I was only able to determine what resistors were needed by the service manual since I could not read the colour bands on them.
R502 to base of q504 appears to be 3M ohm.
I'm not really sure the cause of all of this. I purchased it knowing it had a non functioning status and was hoping to recap it and have a nice amp combined with doing a bit of learning along the way. The resistors in that area were very black as was the board. I was only able to determine what resistors were needed by the service manual since I could not read the colour bands on them.
To confirm, connection between r502 and base of q504 is open or bad connection? Thanks again! I will find it and report back. What am I looking for? 0 ohm between r502 and base of q504?
I do have the diagram. I was just trying to clarify the expected results. Thanks again. After I find the issue, I will follow up.
Ok so not sure why, maybe a via or something, but r502 and r533 both didnt have connection to base of q504. I added some temp jumpers for now for testing. Should I reinstall q503 and e502 and see what happens?
Its a little late here, but I just powered it up in its current (no pun) state, and yes, relays click!! mute is green!! I will do the checks on q504 in the morning unless you think it might be ok to install the other two components and see if everything is working. Thank you so much for your assistance!
I think you could reinstall the other components.
If the relays are engaging, I don't need the voltage on Q504. Confirm that they're relatively close to those shown in the service manual.
If the relays are engaging, I don't need the voltage on Q504. Confirm that they're relatively close to those shown in the service manual.
Everything seems to be in order. Installing in my Scirocco tomorrow. Thank you again for the help and patience. I really appreciate it!!
![DSC_1701[1].JPG](https://www.diyaudio.com/community/attachments/dsc_1701-1-jpg.1213973/ "DSC_1701[1].JPG")
Did you remove the primary to secondary jumper?
Do the RCAs have to be plugged in to get two green lights?
Do the RCAs have to be plugged in to get two green lights?
Only jumpers present now are making up for the broken vias or traces. I cleaned up the routing and length so it wont be a future issue.
RCAs have not been plugged in. Just powered up and let idle for about half an hour. Hope im not jumping the gun here.
RCAs have not been plugged in. Just powered up and let idle for about half an hour. Hope im not jumping the gun here.
Just as a follow up, Ive put maybe half an hour on it after install. Its doing some odd stuff like low level outputs, static, and basically being a little erratic on performance. Should I chalk this up to capacitor burn in time necessary? Im not too convinced that isnt snake oil, but at the same time, my high def sony walkman mentions capacitor burn in time in the owners manual. Would be nice to identify snake oil if thats that case and be prepared for more work. Thanks again, Perry for your patience and help.