Dead NAC552 right channel

Hi i dont know if it is related i am sure i read somewhere allot of manufacturers do not condone the use of carbon cables..... I assume it was the output to the power amp that failed ..... on the 552 there is a stereo extra output you could get a splitter lead and try that......

It sounds as if there may be an issue with your unit..... hmmm thinking...

Tareq, sorry to hear the channel has gone out again. What was the fault diagnosis the first time it went back to be fixed at the factory?  

As Richie says, there's an additional din socket to feed the amp. Identify which is the dud channel and swap it over the the other socket.

The fault diagnosis the first time was a faulty mute-relay, I did not get the details, that was what my dealer communicated back to me. Even if the other DIN socket ends up working, I am not sure I want to keep a device that is not 100% in working order, and definitely not one that has a recurring issue.

I tried the extra output DIN socket to the amp, same result. Dead right channel. 

Seems something that caused the relay to fail, is still there, maybe in the power supply to the 552. 

It's a 20,000 GBP preamp, it is under warranty. 

You did not do anything wrong, your equipment (well, other than the faulty 552) is just fine.

Yep, just want to avoid having to keep sending this beast back and forth to the UK... At this stage I am most curious as to the potential culprits... 

Tareq - sorry not 100% clear to me (but may be inferred from your 1st bullet point) - did you try other inputs on the 552?

Yes, tried other inputs, including the RCA inputs...

Tareq, for a relay to fail once is possible but unlucky.  To happen twice is not just really unlucky but maybe being caused by something else somewhere in the system?  It might be a good idea to consult with Naim's service department on this.  

This was my thought too ..... although i find it hard to understand why the mute relay should be activated. It has been noted these preamps are very sensitive to static - I wonder if your environment - is prone to static ... I know when it is really dry - I get allot of static shocks from the car and door handles etc...... it must be really dry where you are......

There can be external factors.  I remember some years ago a pre/power (I think it was a 552 and 300) that came in with faults, was fixed butthen came back again a few weeks later with the same faults. The customer was obviously not happy and rather pissed off with Naim.  However, Naim  asked for the source to be submitted to the service dept (a very expensive digital source from another maker) and leaving the system plugged in and playing for a few days it transpired that the source had a faulty SMPS that would very now and then send a spike through the system, and this was causing the failure further down the chain.

Static can be a an issue too, although it depends on the earthing, and usually it just means you lock up the controls - a power cycle normally clears it.

Richard Dane posted:

There can be external factors.  I remember some years ago a pre/power (I think it was a 552 and 300) that came in with faults, was fixed butthen came back again a few weeks later with the same faults. The customer was obviously not happy and rather pissed off with Naim.  However, Naim  asked for the source to be submitted to the service dept (a very expensive digital source from another maker) and leaving the system plugged in and playing for a few days it transpired that the source had a faulty SMPS that would very now and then send a spike through the system, and this was causing the failure further down the chain.

I find myself wanting to know what the customer thought of Naim when they heard that and whether or not they still have the expensive non-naim source.

So as ever from me, how did it end?

Sorry Chris, I have no idea what the owner did with the system after that.

Ok, thanks. C.

Dry and static are not the issue here, I live in a very humid County where 85% humidity is common, I never had any static issue either. 

My digital source is a Chord Dave unit. 

I use Dave with my 282, no issues, friend in Dubai uses Dave with 552/500, no relay problems.

I think Gary shaw also uses with his 552/500 no relay problems.

The relay, however, is powered by a SNAIC cable from the 552, maybe you got a bad SNAIC cable.

The Snaic theory is interesting, I am not sure that a faulty Dave would be able to spike the loop so much as to damage the 552 yet continue working as normal... It is more likely something between the Nac552 and the 552ps

@Richard Dane, the naim service folks are involved 

Thanks Tareq.  Yes, I sent Steve a link to your thread on here.

Tareq -

I lost a channel (not both) on my 552 post a lightning strike close by - thankfully it came back OK post a power down and no harm was done.

I'm unclear what caused this 'jolt' e.g. was it via the garden earth cable I have or simply a surge on the mains supply. I don't think it was the latter as other electrical goods in the house were OK and the hi-fi has dedicated earthing arrangements (noting again that only channel dropped and the rest of the kit was OK).

Something to think about around earthing?

I have to admit I am a bit twitchy re my equipment being spiked..... it might pay to somehow have your mains checked..for noise,  voltage and earthing.... I am not sure how you do this.....

Hi I have been thinking about this mute relay issue..... logic tells me that what ever controls the relay .... is malfunctioning. This is nothing to do with the audio circuits .... it must be a either a computer glitch.... or sub circuit failure. Is there any way of totally re setting logic control ..... other than switching off.....

Richieroo posted:

Hi I have been thinking about this mute relay issue..... logic tells me that what ever controls the relay .... is malfunctioning. This is nothing to do with the audio circuits .... it must be a either a computer glitch.... or sub circuit failure. Is there any way of totally re setting logic control ..... other than switching off.....

Normally a long power off resets everything - caps discharge fully so you can't get anymore 'reset' than this. I'm sure Naim will get to the bottom of this with the OP. 

Since this is the second time this happened I am sure that whatever Naim fixed the first time was not taking care of the root cause. 

I hope to be honest that this is a faulty component in the Nac and not something outside, it would be pretty hard to troubleshoot other factors such as cables, DAC, electricity, etc. 

I have lost confidence in the particular unit I purchased from Naim, I feel like this issue and potentially other issues lurking around will only happen again and again. 

If I was living in the UK I would cope with it better, but spending 2 month each time waiting for my unit to ship to UK and back is silly given the amount of investment I made to have the best experience... 

Another thing that I often think about is the choice of connection between the Chord Dave and the Nac552, today I am using an RCA-2-DIN cable, I could also use the standard RCA interconnect. 

I am using the RCA-2-DIN cable due to a belief that Naim is basically better suited for DIN connections and that may have a better sound quality.. 

Could the issue be attributed to the choice of interconnects?