Hello.
NAD 3020 integrated amplifier.
Model with 4 big caps in center.
Amplifier works fine.
The sound is clean,very great engine.
But right channel crackling.
Volume on zero.... crackling.
Pre amp.....no cracks
I replaced 2 power transistors....no success.
No bad soldering,no suspects parts.
All potentiometers and switch was cleaned.
This sound is similar when you fry bacon.
if I turn up the sound, then this noise is not heard.
Regards
Service manual
NAD 3020 SM Service Manual download, schematics, eeprom, repair info for electronics experts
NAD 3020 integrated amplifier.
Model with 4 big caps in center.
Amplifier works fine.
The sound is clean,very great engine.
But right channel crackling.
Volume on zero.... crackling.
Pre amp.....no cracks
I replaced 2 power transistors....no success.
No bad soldering,no suspects parts.
All potentiometers and switch was cleaned.
This sound is similar when you fry bacon.
if I turn up the sound, then this noise is not heard.
Regards
Service manual
NAD 3020 SM Service Manual download, schematics, eeprom, repair info for electronics experts
Did you check bias? If too low can cause some distortion.
I assume all voltages are correct since you say otherwise the amplifier works normally?
I assume all voltages are correct since you say otherwise the amplifier works normally?
If you say it works fine from pre-out then it is either volume pot (although you cleaned it, have you checked for consistent resistance change with DMM?)
Is the crackling on one channel or on both? Try to verify if you haven’t already, by disconnecting one sides pre-amp plug.
What transistor(s) did you change? I would start with checking the small signal transistors q601, 603, 605, 607 and 609. Possibly start with freeze spray or heat and see if crackling goes away.
If so you found the culprit.
Is the crackling on one channel or on both? Try to verify if you haven’t already, by disconnecting one sides pre-amp plug.
What transistor(s) did you change? I would start with checking the small signal transistors q601, 603, 605, 607 and 609. Possibly start with freeze spray or heat and see if crackling goes away.
If so you found the culprit.
Only right channel Noisy
The volume potentiometer is in good working order,the preamplifier works fine,no noise
The volume potentiometer is in good working order,the preamplifier works fine,no noise
With loudspeakers 2 power transistors are very hot on right channel
Wisouth no problems......
With headphones no problems.
The loudspeakers are in good working condition
Wisouth no problems......
With headphones no problems.
The loudspeakers are in good working condition
Which two? Q-what #
Sounds like oscillation if you checked bias - does it change with a very small signal input? If oscillating your bias would increase or fluctuate.
Sounds like oscillation if you checked bias - does it change with a very small signal input? If oscillating your bias would increase or fluctuate.
Go back and check the transistors I mentioned earlier.
Can only be excess current going through those outputs heating them up. So you have an out of tolerance resistor or a bad transistor or both causing the over heating. Cause could be faulty bias, parts or oscillation. So should be easy to find with the schematic.
Can only be excess current going through those outputs heating them up. So you have an out of tolerance resistor or a bad transistor or both causing the over heating. Cause could be faulty bias, parts or oscillation. So should be easy to find with the schematic.
just swap for a new volume pot. If there are 3 legs resistor pot on the pcb, change the one at the right channel.
Bonne chance, un bon petit ampli !
.
Bonne chance, un bon petit ampli !
.
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I had similar issues on an early 3020. Check all of the PCB traces for breaks--they are 40 yrs old--especially where parts have been replaced. I also remember having issues with electrolytics C625/626 (47uF 25v) until I replaced them with 50v units. C615/616 (1000uF 6v3) were replaced with 25v (or 35v) units. Measure the existing diameters and find something that fits in the existing space. I did this over 18 months ago and have had no issues since and the amp is turned on and off daily. Good luck!
There's a 3240PE thread with similar issues. Both use breakers for protection....probably worth checking the breaker on each channel. Maybe bypass the "bad" one and see if the noise is gone.
Was the test of cooling ALL TRs of the noisy channel performed?
Although it is puzzling that the headphone jack is not noisy, it is normally taken from the output, but you do not see the circuit in the link, it only leads to a download site, upload the circuit in PDF directly.
An intermittent track / weld can cause that crackling, as you have been pointed out.
With a lot of patience, you can buy the tracks on the power board:
1)
With an ohmmeter function tester and the amplifier off, see if there are oscillations in any measurement.
2) With the amplifier working, listening to the speakers without music and bridging between solder points joined by the tracks, but you will have to have a very good pulse in this case .....
Although it is puzzling that the headphone jack is not noisy, it is normally taken from the output, but you do not see the circuit in the link, it only leads to a download site, upload the circuit in PDF directly.
An intermittent track / weld can cause that crackling, as you have been pointed out.
With a lot of patience, you can buy the tracks on the power board:
1)
With an ohmmeter function tester and the amplifier off, see if there are oscillations in any measurement.
2) With the amplifier working, listening to the speakers without music and bridging between solder points joined by the tracks, but you will have to have a very good pulse in this case .....