Thanks for the advice Johnips. I’ve just fitted a 10uf 25v capacitor in the suggested location, still no success. The 5V is present but measuring at the output plugs of the psu b board the 12.5V is definitely not starting up. I pulled the MDC cards in case the fault was there. No dice.
Pulling the MDC cards is a bad idea, and I experienced it beeing a cause of not starting up once. I would opt for a larger cap than 10uF as this is right on the threshold, but should start any way. Have you changed the caps around and including the high voltage one?
Sorry, I typo’d the previous message. Additional capacitor is 47uf, 25v. Yes, I changed all the caps in the 12.5v part of the board including the 400V one. I’ve marked the changed caps in the photo above. (Plus two more under the heat sink)
I see some soldering on the picture that may be no good any more? This is a simple circuit and should be easy to fix? Start by measure the voltages. Then the 431. Good luck.
I have read this topic with interest. I purchased my NAD c390dd in 2012 or so and after a couple of years it started showing this issue. When warranty expired in 2017 it completely stopped working and from then I sank a lot of money into repairs (main board, PSU 2x), and the same issue keeps resurfacing.
It starts with occasionally not starting up with a black screen, to gradually always not starting up properly. When it does start up it does sound great (although not as good as my new Arcam SA30). It is now in use as my second amp in my home office running a pair of B&W 601S3 loudspeakers, which is quite ridiculous comparing the cost difference.
After the 3rd repair (after finding pieces of exploded capacitator inside) it has ran quite flawlessly for another year or so, now giving the same shite.
It frustrates me that nothing seems to be wrong with the other components, except this, which is then being solved with new **** components.
I am not an electrotechnical guy that has experience soldering and replacing capacitators, but it frustrates me that this limitation may require me to trash this piece of junk, which would otherwise be cheap to fix. This is the 3rd time at the crossroad of thinking should I trade it in for whatever it is worth, or should I sink more money into this sinkhole.
Knowing what I paid for it initially makes me hesitant to just write it off, but sinking in 100's every year to extend the lifespan another year is not my preference either.
It starts with occasionally not starting up with a black screen, to gradually always not starting up properly. When it does start up it does sound great (although not as good as my new Arcam SA30). It is now in use as my second amp in my home office running a pair of B&W 601S3 loudspeakers, which is quite ridiculous comparing the cost difference.
After the 3rd repair (after finding pieces of exploded capacitator inside) it has ran quite flawlessly for another year or so, now giving the same shite.
It frustrates me that nothing seems to be wrong with the other components, except this, which is then being solved with new **** components.
I am not an electrotechnical guy that has experience soldering and replacing capacitators, but it frustrates me that this limitation may require me to trash this piece of junk, which would otherwise be cheap to fix. This is the 3rd time at the crossroad of thinking should I trade it in for whatever it is worth, or should I sink more money into this sinkhole.
Knowing what I paid for it initially makes me hesitant to just write it off, but sinking in 100's every year to extend the lifespan another year is not my preference either.
Story of my life, I never bothered to take it in for repairs during warranty thinking it was a software issue and not wanting to be without amp for a month, to have it die on me after warranty expired.
Hi all,
First off, thanks for this thread! It's been helpful for me, but ultimately I had another issue which looked exactly like this one but now appears to be stuck relays so thought I should report that here.
I bought a C390DD used in like 2020, then liking the flexibility and BluOS streaming add-in MDC card so much, eventually bought a second one. All has worked generally well though one of the units started showing very occasional symptoms of what looks like the power-on problem mentioned in this thread (press power on, light turns blue, one relay click can be heard, then nothing else happens and pressing the power button again can't turn it off), but each time generally just turning off the power supply switch in the back then back on would manually "reset" it. About a year ago those symptoms got worse until finally it would fail to start up several times in a row until it warmed up, but getting worse until recently it stopped working altogether. I pondered what was wrong with it, but finally found a bit of time recently (a month or so ago) to look up on the net, and found this thread on the PSU-B issue.
Finally a week or so ago I had the replacement parts ready and the unit opened up... pulled the various capacitors recommended here and checked their values, all has looked pristine and the values checked out. Hmm, so then added the recommended 47uF cap in the spot. All of this didn't change anything.
So then decided to take out the other unit and swap in the PSU-B's between them, and lo and behold, the failing unit still fails and the working unit still works, which means the PSU-B was fine. Pondering random things but basically back to square one.
Then there was a small accident where I dropped the failing unit a short distance. Not enough to break apparently anything but it got a good solid jolt on my work table. Concerned I'd broken something even worse I dutifully plugged it in to make sure it was as ... ok as it was before at least, but NO, IT WORKED.
After this, it worked for a few days then stopped again, and a good stiff jolt made it start working again, etc. I'd previously looked to see if there were loose cables, components, etc. and everything was tightly connected, still the case. So there's either some stuck relays or a weirdly loose component. I'm going with the stuck relay theory for now.
All this leads to my question for the forum and those who've looked closely at the PSUs and circuit diagrams. Are the initial relays for the power on sequence in the PSU-A, or somewhere else?
First off, thanks for this thread! It's been helpful for me, but ultimately I had another issue which looked exactly like this one but now appears to be stuck relays so thought I should report that here.
I bought a C390DD used in like 2020, then liking the flexibility and BluOS streaming add-in MDC card so much, eventually bought a second one. All has worked generally well though one of the units started showing very occasional symptoms of what looks like the power-on problem mentioned in this thread (press power on, light turns blue, one relay click can be heard, then nothing else happens and pressing the power button again can't turn it off), but each time generally just turning off the power supply switch in the back then back on would manually "reset" it. About a year ago those symptoms got worse until finally it would fail to start up several times in a row until it warmed up, but getting worse until recently it stopped working altogether. I pondered what was wrong with it, but finally found a bit of time recently (a month or so ago) to look up on the net, and found this thread on the PSU-B issue.
Finally a week or so ago I had the replacement parts ready and the unit opened up... pulled the various capacitors recommended here and checked their values, all has looked pristine and the values checked out. Hmm, so then added the recommended 47uF cap in the spot. All of this didn't change anything.
So then decided to take out the other unit and swap in the PSU-B's between them, and lo and behold, the failing unit still fails and the working unit still works, which means the PSU-B was fine. Pondering random things but basically back to square one.
Then there was a small accident where I dropped the failing unit a short distance. Not enough to break apparently anything but it got a good solid jolt on my work table. Concerned I'd broken something even worse I dutifully plugged it in to make sure it was as ... ok as it was before at least, but NO, IT WORKED.
After this, it worked for a few days then stopped again, and a good stiff jolt made it start working again, etc. I'd previously looked to see if there were loose cables, components, etc. and everything was tightly connected, still the case. So there's either some stuck relays or a weirdly loose component. I'm going with the stuck relay theory for now.
All this leads to my question for the forum and those who've looked closely at the PSUs and circuit diagrams. Are the initial relays for the power on sequence in the PSU-A, or somewhere else?
A good visual scan is always the best approach to start with.
Cold solder joints. Broken wires. Burnt components etc etc.
I would be changing the relays as they sound past their best.
Cold solder joints. Broken wires. Burnt components etc etc.
I would be changing the relays as they sound past their best.