Naim NAIT2 (Pre Amp) + NAP 90 Signal Drop Out

[Richard Puleston]

Hi All

I've had the Naim combo (playing through a pair of Linn Kelidh) for about 25 years and it has all, as folk might expect, been brilliant from day one. Yesterday, however, it has developed the following fault. The signal fades on the left channel and then jumps back to full strength. This happens when playing vinyl or CD.

Has anyone experienced anything similar or have a clue where to start looking to fix it. I'm kind of presuming its the NAIT and not the NAP.

Thanks

Richard

 

[Craig B]

First, I'd try reseating the signal DIN between NAIT and NAP both ends, and also check that the banana plugs are still making a decent tight connection, and that a 4mm socket hasn't come free of the NAP board (by wiggling the inserted banana plugs about).

Barring any of the above as cause, you'll need a multimeter with which to test output with, in order to isolate the component that is at fault. Nothing fancy, even an old analog meter will do. The reason being that the one downside with DIN connections both ends is that it isn't feasible to isolate the component at fault via transposing the L/R channels between the amps in order to determine whether or not the fault changes sides. IOW, should the fault change sides, it is the NAIT (or interconnect), otherwise its the NAP.

Using a multimeter with red and black probe tips into ch1 and -ve of the output socket on the NAIT, whilst outputting signal, would let you know the same, i.e. no drop in Lch output indicates the SNAIC or the NAP to be at fault by process of elimination. You can also use the meter to check the SNAIC.

 

[Richard Puleston]

First, I'd try reseating the signal DIN between NAC-NAIT and NAP both ends, and also check that the banana plugs are still making a decent tight connection, and that a 4mm socket hasn't come free of the NAP board (by wiggling the plug about).

Barring the above, you'll need a multimeter with which to test output with. Nothing fancy, even an old analog meter will do.

One downside with DIN connections both ends is that it isn't feasible to isolate the component at fault via transposing the L/R channels between the amps in order to determine whether or not the fault changes sides. IOW, should the fault change sides, it is the NAC-NAIT, otherwise its the NAP.

Using a multimeter with red and black probe tips into ch1 and -ve of the output socket on NAIT-NAC, whilst outputting signal, would let you know the same, i.e. no drop in Lch output indicates the NAP at fault by process of elimination.

Thanks Craig

I don't but I know a man who does (have a multimeter).

 

[Craig B]

Thanks Craig

I don't but I know a man who does (have a multimeter).

Sounds good.

In the meantime, I'd also suggest 'exercising' the volume and balance pots, as well the source selector switch to determine if the drop in Lch has anything to do with excess contact resistance here. Even the mon/normal/mute switch could be culprit here.

Even on amps that get regular use, the balance pot may not get touched for years on end. I'd give both the volume and balance pots a few turns through their full range of travel (with no signal playing in the case of the volume control) in order to determine whether or not this action causes the Lch to come back up again. Any crackling sounds through the speakers when adjusting these pots is a clue that they need attention.

 

[Richard Puleston]

Sounds good.

In the meantime, I'd also suggest 'exercising' the volume and balance pots, as well the source selector switch to determine if the drop in Lch has anything to do with excess contact resistance here. Even the mon/normal/mute switch could be culprit here.

Even on amps that get regular use, the balance pot my not get touched for years on end. I'd give both the volume and balance pots a few turns through their full range of travel (with no signal playing in the case of the volume control) in order to determine whether or not this action causes the Lch to come back up again. Any crackling sounds through the speakers when adjusting these pots is a clue that they need attention.

I'll give all of that a try. There is occasionally some crackle when adjusting the volume. Maybe it needs a clean/service.

 

[Craig B]

Does fiddling with the volume control make the Lch drop off and/or come back up in level compared to the Rch?

Or, is it just a bit crackly?

 

[Richard Puleston]

Does fiddling with the volume control make the Lch drop off and/or come back up in level compared to the Rch?

Or, is it just a bit crackly?

It can be a bit crackly when I adjust the volume but the changing the volume doesn't bring the 'drop off' on. The new drop off thing happens randomly when I'm playing music.

 

[BlueYeti]

My Nait2 was displaying similar symptoms which worsened quite quickly over a couple of months, so I sent it off to Darran at ClassA for a service. All problems gone and it came back sounding so much better.

 

[Richard Puleston]

It can be a bit crackly when I adjust the volume but the changing the volume doesn't bring the 'drop off' on. The new drop off thing happens randomly when I'm playing music.

Hi Craig

So, I've done all you said and, for now at least (2 records), it seems to have cleared the fault. I also took the opportunity to open up both boxes and all of the electrics look like they are in good health.

So, thanks for your input and suggestions.

Kind regards

Richard

 

[Richard Puleston]

My Nait2 was displaying similar symptoms which worsened quite quickly over a couple of months, so I sent it off to Darran at ClassA for a service. All problems gone and it came back sounding so much better.

Hi

It would seem I have fixed it for now but I am interested in what you got for your service (and what order of cost it was)?

I am in Somerset and there is a shop in Bath who look after Naim, but they have set their doors for the time being. I might investigate when normality returns!

Cheers

Richard

 

[badlyread]

A Nait service by Darran at Class A will be about £200 including collection and return. I imagine it will be similar for the NAP 90. All caps will be replaced and moving parts cleaned. It will be completely checked over. Darran is the only authorised Naim repair agent outside of Naim themselves. His work has always been excellent.
He is cheaper than Naim and Witch Hat Audio.

Email: [email protected].

 

[Craig B]

Hi Craig

So, I've done all you said and, for now at least (2 records), it seems to have cleared the fault. I also took the opportunity to open up both boxes and all of the electrics look like they are in good health.

So, thanks for your input and suggestions.

Kind regards

Richard

Glad to hear it, Richard!

I'd suggest picking up a spray can of DeoxIT FaderLube F5 for the next time you have a peek inside. This isn't cheap, however, a can will last a lifetime and is the ounce of prevention that can save many pounds of cure.

Craig

 

[TLS]

My Nait 2 developed the same problem. Focal Naim America had to change the input selector.

 

[BlueYeti]

Hi

It would seem I have fixed it for now but I am interested in what you got for your service (and what order of cost it was)?

I am in Somerset and there is a shop in Bath who look after Naim, but they have set their doors for the time being. I might investigate when normality returns!

Cheers

Richard

The cost was £200, and that included Darran arranging booking DHL courier each way. I had dropping channels, intermittent sound coming from one channel the signal zoning in and out, severe crackling when using the volume control and switches, which also felt notchy and rough. Now, it sounds superb, and all controls are butter smooth again. When he opened it up it was all original inside, as it had just left the factory so well overdue for some TLC. As mentioned already, ClassA are the only Naim authorised service agent in the UK. Turn around was just a week (last summer). Highly recommended. Full list of work done..

Full service and re-cap, align and test,
10 x 10uf @ 35 volt tantalum capacitor
2 x 47uf @ 6.3 volt capacitor
1 x 3300uf @ 25 volt capacitor
2 x 68000uf @ 25 volt capacitor
4 x 47uf @ 35 volt capacitor
7 x 47uf @ 25 volt capacitor
4 x 10uf @ 35 volt capacitor
4 x cabinet foot and screw

Hope that helps.

 

[Craig B]

That should be 2 x 6800uF @ 25V capacitor there, @BlueYeti.

Although Naim and their authorized service agents have also been putting Kemet ALC20A103DC040 10000uF 40V caps in place in recent years, as the current Rubycon equivalent of the 6800uF originals are getting difficult to source.

 

[BlueYeti]

That should be 2 x 6800uF @ 25V capacitor there, @BlueYeti.

Although Naim and their authorized service agents have also been putting Kemet ALC20A103DC040 10,000uF 40V caps in place in recent years, as the current Rubycon equivalent of the 6800uF originals are getting difficult to source.

Thanks Craig, corrected. The devils of copying and pasting directly! Interesting that the original caps are becoming hard to source. Wasn't aware of that. Are there performance gains to be had from fitting non standard serviceable parts? This is the first piece of Naim gear I've needed to have serviced (always sold on before that stage), so I took the cautious approach to preserve originality this time round, and went via the factory endorsed route.

 

[Craig B]

@MJS would be the man to answer that question.

I'm also a purist when it comes to restoration/repair vs. modification; especially so, when it comes to things that have a certain baked in goodness.

I'll also pay more for original, unadulterated examples, or for to factory spec serviced ones.

 

[BlueYeti]

@MJS would be the man to answer that question.

I'm also a purist when it comes to restoration/repair vs. modification; especially so, when it comes to things that have a certain baked in goodness.

I'll also pay more for original, unadulterated examples, or for to factory spec serviced ones.

Understood, perhaps @MJS will chip in with extra info. As my Nait is a near mint CB Nait2, thought it better to keep everything as is.

 

[PerF]

Actually I can't remember many using Nait 2 as preamp with a 90.
Rather refreshing
I've had loads of them but never in that configuration.

 

[Craig B]

Actually I can't remember many using Nait 2 as preamp with a 90.
Rather refreshing
I've had loads of them but never in that configuration.

I suspect that not many would have had the pre-out option fitted as it went against the Naim standard of having a separate external power supply for their pre-amps. In this case, the signal is branched to the DIN4, with the internal power supply still in circuit (hence the DIN4 socket being labelled as ch.1, ch.2, -ve, and nc).

When NAIT 3 came along, the official conversion was to NAC92, with NAP90 being left within should one wish to revert back to NAIT. It didn't take long for sharp-eyed Naimies to notice that beneath the rear plastic fascia lay all the pre-drilled holes as necessary for the one case to be shared amongst the whole series. With 1 additional DIN4 socket and a DIN4 to DIN4 jumper, one could have three amps in one, with or without FLATCAP.

I've had a minty looking NAIT 3 sitting here for a number of years now with a dead channel on the NAP. I haven't got round to opening it up to see if that side is repairable. If not, I'll likely do a full NAC92 conversion (i.e. pull the NAP90 board and transformer) and sell it on. If the NAP90 board hasn't been badly damaged, I'll likely as not go for a repair plus partial recap (and may as well do the full-split conversion while all is apart).

NAIT 2 with optional pre-amp output fitted: