Yes, weird. They are fusible, but this explains partly only the problem.
Why thy fused now after 25 years of working and when there is no other failures in amp?
Why thy fused now after 25 years of working and when there is no other failures in amp?
Hello.
Sorry for hijacking thread, but I have problem with NAD 216 and protection mode as well. When I bought the amp, maybe two years ago, it worked all right. Now it intermittently goes in/out of protection. When amp is first turned on after being off overnight, it takes long time for the led to turn green and relay to click, sometimes one or two minutes. When turned off and on subsequently, it takes only a few seconds, as it should. And sometimes when running, it goes in to protection mode for a few seconds and then comes back. Does someone please have an idea what could cause this problem, which is I guess intermittent DC on output? I measured power supply voltages, they are ok, and so is regulated +67V and -67V. Idle current test point voltage is 12,5mV, manual says it should be 18mV +-1,5mV. Could it be caused by this? I also measured some resistors that were mentioned as problematic and did not find any that was shorted or open. Could it be problem with relay? I have new one, but did not change it yet.
Thank you.
Sorry for hijacking thread, but I have problem with NAD 216 and protection mode as well. When I bought the amp, maybe two years ago, it worked all right. Now it intermittently goes in/out of protection. When amp is first turned on after being off overnight, it takes long time for the led to turn green and relay to click, sometimes one or two minutes. When turned off and on subsequently, it takes only a few seconds, as it should. And sometimes when running, it goes in to protection mode for a few seconds and then comes back. Does someone please have an idea what could cause this problem, which is I guess intermittent DC on output? I measured power supply voltages, they are ok, and so is regulated +67V and -67V. Idle current test point voltage is 12,5mV, manual says it should be 18mV +-1,5mV. Could it be caused by this? I also measured some resistors that were mentioned as problematic and did not find any that was shorted or open. Could it be problem with relay? I have new one, but did not change it yet.
Thank you.
Same problem I had with my 216 - try a couple things to possibly confirm. Measure DC before the relay, so direct from amplifier board. If it's <250mV then suspect the relay. Next confirmation (let's scientific) take a rubber end of a screwdriver (or pencil eraser) and tap lightly on the relay, if it closes/open with the tapping then you have bad relay contacts. With a 25+ year old amp, changing the relay is a must if you intend to keep it and listen to it.
So I measured DC before relay. After turning amp on, one channel had zero, the other around 61V. After a minute or so, 61V fell down to zero and relay clicked. Problem is definitely DC on output, at least now I know which channel.
Edit:
I did not manage to measure IC 201 in time. I measured it during period when it was clicking on and off after a few seconds for about a minute.
Edit:
I did not manage to measure IC 201 in time. I measured it during period when it was clicking on and off after a few seconds for about a minute.
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IC201 voltages are OK, and they must be as protection was not on during measurements.
It is possible that problem is in plugs and sockets what are going to amp board. There are 2 of them on amp boards, input and voltage plugs, bad contact on both can cause 60V on amp output what cause protection activation.
It is possible that problem is in plugs and sockets what are going to amp board. There are 2 of them on amp boards, input and voltage plugs, bad contact on both can cause 60V on amp output what cause protection activation.
It seems that all connections are good. But I found one thing. The good channel has around 5mV on input (the small connector, am I right?). The bad channel has tens or sometimes more than hundred mV on this connector when ther is DC on output. Could this be indicative of what is wrong with this channel? Or input/power supply board? Thanks
This DC on input is not problem cause but result of DC on output. NAD 216 amp have servo opamp IC201 what try to regulate 0 V to output with adding DC to input.
Probably yes, it is possible also that IC201 or related components have some failure but more likely is that plugs and sockets have no good connection, specially input socket on amp board.
Hello i am little late to the party but when repairing my 216 one simple thing that one might overlook ( as i did while working on it ) is proper grounding of the pcbs to the chassis make sure to double check those screw and pcbs underneath for corrosion and or a bad connection. I also had bad input connections from rca in ( source) to the amp boards i replaced the push in type (original) to block type with set screws. I have a thread on my repair
https://www.diyaudio.com/community/threads/nad-216-help-needed.330113/
https://www.diyaudio.com/community/threads/nad-216-help-needed.330113/