NDS or NAC552 fault?

I am looking for advice. My system is NDS, NAC552, NAP500. A week or so ago I lost all sound. It’s probably related to the hurricane and power outages we had recently. I am 1500 miles away from the nearest Naim dealer so I need to isolate which bit of the system is at fault so I know what to send to Naim for repair. I suspected the problem was the NDS as it has a blank screen including when I reboot and / or I press “disp” on the remote. Unfortunately, when I switch to the NAT 01 tuner I don’t get sound from this either. Nor does my iPhone work (albeit that it’s connected through a series of jury rigged leads which looks as though it should work but I am not entirely confident about). On this basis, I suppose it’s the preamp that’s faulty but I’m concerned about the NDS screen issue. Any suggestions as to how to confirm this further?

Do you get a very small amount of hiss through the speakers still?

I will have to check but there is definitely a “pop” when I turn the system on / off.

If you aren’t getting any sound through any source, regardless of input on the pre-amp then it would seem to indicate a pre-amp issue. Perhaps @NeilS could give some insight here?

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Just managed to check. There is no background hiss. If that means it’s a preamp issue, is there any way of pinning down whether the NDS is working?

Had the NDS screen already failed or did this happen at the same time?
Where are you connecting the iPhone, to the NDS USB or analogue into the 552? Maybe try both just in case.
You really need another preamp to test the streamer output. Do you have anything else with a line in (pre volume control)?

I don’t know whether the NDS screen went at the same time or not.
The phone is connected to a preamp DIN input. I haven’t tried it into the NDS USB yet. I will do that and report back.
I have nothing else I can input the streamer into. There is a vague possibility I can get some local help linking it up to another system. Nothing is made easier by the fact that DIN leads don’t exist here, thus the reason why I am jury-rigging the iPhone connection.
Thinking about it though, even if the streamer has any output, I still need to fix the screen problem anyway, so it will most likely have to get shipped to the UK. Unless it is a simple local fix, which seems unlikely.

Where are you? Is there a local Naim distributor or authorised service agent who can help?
Naim make a 3.5mm jack to DIN lead, as do a few other cable suppliers if that’s what you need, although USB into the NDS might be a better option. If you try this, use iTunes/Apple Music first as a test as other apps don’t always work this way.

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He says he’s 1500 miles from the nearest Naim dealer Chris!

If the NDS is visible on the network and responds to the Naim app, then maybe it still works ok and the screen is a separate issue. If the NDS isn’t visible on the network, then is the power supply providing power ok (power supply logo on the power supply and the NDS alight) or maybe there is a fuse issue. The OP needs to exclude a power supply problem. Otherwise he might send back the wrong boxes.

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There is a chance both boxes at fault if you had a bad power surge.

If there is no hiss and no sound from any source, it could not just be the 552 but also the 500 at the end of it all, unless I am missing something.

The most helpful people technically, is Linda’s Disco. That’s the level of expertise here. I can ship a lead in from USA but it takes 2 - 3 weeks, so don’t really want to leave it that long. Direct USB input still to test.

The NDS is visible in the App and appears to respond but obviously I don’t know if it’s actually doing anything as I have no sound. Power supply logos are green on everything.

NDS blank screen aside, you say you get no sound from the NAT01 either. I assume the tuner input is selected and the tuner is connected to input 3 (default input mapping) ? From what you say about the logos all lit up, it sound like it’s all powered up ok. What buttons are illuminated on the 552 ?

Unless you’ve not done so already, it might be worth powering down the 552 and 500 and leaving them off for a good 1/2hr. Power up the 552 first and then the 500 and see if you get sound from the tuner at least (I’m assuming you are able to tune to a favourite station - you’ve not lost your antenna in the storms !)

With the distances involved it maybe worth buying a used Nait at least you can try your sources and if the 552 is at fault you have a backup to play music whilst the 552 is away for repair.

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Hi Andrew,

You don’t say whether you have disconnected/reconnected anything recently due to the storms?
If so, check you have the left & right XLR leads the correct way round into the 500.
Check that the corresponding small LED above the input sockets on the 552 rear panel lights momentarily when you press the relevant input button on the front (just to check the inputs are mapped as expected.)
You could also try disconnecting the interconnect at the NDS end & touching the pins at the end of the cable with the 552 volume set at about 9 o’clock on the dial, this should create a noticeable hum if the preamp & power amp are working.



Nothing from the iPhone into NDS USB.

Nothing has been connected / disconnected, so its not the XLR leads.
The green LED on the back of the 552 confirms the NDS is plugged in to the correct DIN input.
There is no hum when I do as you suggest with the NDS end of the interconnect.
Subject to any other advice, the conclusion I have reached so far is:

  • The NDS screen is not working, so regardless of whether it is actually producing an output, I have to send it for repair.
  • It’s most likely that the 552 is not working, so that needs to go for repair as well.
  • I am not sure about the 500. At the moment, I am minded to leave it and see whether it works when the NDS and 552 come back - unless there is any way that I can check it further?
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Completely agree on the way forward with the NDS.
The fact that the speakers pop on power up/down is a good sign for the 500, the fact that there is no detectable low level hiss/white noise - not so much.
If it is indeed a fault with the 552, it could be a power supply issue - is it a 552PS DR? Reason for asking is they have sacrificial low value resistors on the output of each module for protection & electrical storms could well have damaged them.
Normally substituting units for known good ones to ascertain which unit is at fault would be the thing to do, but I understand that may be difficult due to your location.



Not an option, I am afraid. We are on 120 v 50 Hz, so it would mean getting it altered by Naim.