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Naim NAC112 changes volume all by itself - help!

T

thesurfingalien

New Member
Hi All,

As the title says, my Naim NAC112 changes volume all by itself. In the past I have found out this is caused by an issue with the IC that routes the signal through an array of resistors.

The problem is that it is too expensive for me to have it repaired in Sao Paulo (I obviously live in Brazil). Insured shipping is not cheap, and I expect the bill for the repair to be quite high.

I could probably fix the issue myself, but I have trouble locating the mentioned IC. Anyone can help here?

On another note, my CD5 no longer plays a CD correctly; it often just stops. My guess is the CD-transport got damaged during shipping... Any advice here?

Thanks in advance & Kind regards!
Peter
 
Top tip - try a few basic checks / diagnostics yourself before spending any money -

When you say 'changes volume by itself' -

As a sudden step - which may be typically a loose connection or dry joint - if so does it happen on all inputs? Even check the interconnect leads by wiggling them.

Or a gradual up and down - if so look at the volume control potentiometer - and see if it is physically moving. Don't forget on the nac 112 these are motorised pots - to work with remote control - don't over look remote controls can do funny things in themselves - particularly if picking up spurious signals from other such devices nearby.

I have experienced this several times with the naim remotes.
 
This is a known problem on the 112, apparently just a change of the controller IC solves the problem, the volume is controlled on a logic switched resistor ladder network and the controller chip goes haywire resulting in the volume jumping around so cleaning the pot makes no difference.
I believe the chip is in a socket on the back of the front control panel PCB.
Naim did a replacement IC for this but it needs to go back to the dealer to be fitted.
 
I had a 112 that had strange volume issues, this was fixed with a software reset.

"To restore all programmable settings to the factory defaults press and hold the remote handset disp key while the preamplifier is in program mode. The preamplifier will exit from program mode following this operation."
 
yairf said:
You may start by cleaning the volume pot (take it apart first) or go all the way as I did...
Click to expand...
If you can't get hold of the chip, sending it back to Naim would be expensive, I'd guess more than you could by a replacement for. Getting it done by an authorised workshop may be reasonable, but I don't know if you have those where you are. However, if I was you and you've already stated you want to DIY, look at Yair's thread above. If you do the volume control mod OK you may be tempted do the others mods too and it'll improve the pre by miles I'm sure.
 
Emile_A said:
This is a known problem on the 112, apparently just a change of the controller IC solves the problem, the volume is controlled on a logic switched resistor ladder network and the controller chip goes haywire resulting in the volume jumping around so cleaning the pot makes no difference.
I believe the chip is in a socket on the back of the front control panel PCB.
Naim did a replacement IC for this but it needs to go back to the dealer to be fitted.
Click to expand...

Hi Emile,

I was informed about that shortly after the problems started, and I was advised to contact a specific person that works for Naim, which I did.

It apparently is an issue that introduced itself shortly after the NAC112 was introduced. I asked why Naim had not done a recall to fiix the problem before I ran out of warranty, but that remark was not taken very kindly.

I should have mentioned this in my post, but I assumed this was common knowledge... I also should have mentioned that I did all checks and the firmware-reset.

Thanks for all responses so far, and if anyone has more info I wuld appreciate it!

Regards,
Peter
 
Sorry guys, I don't touch these. I believe the problem is due to the rotary encoder and electronics that read the position of the volume control. Shortly after introduction those electronics became obsolete. It really isn't one of Naim's finest products. You are much better off with a 102 and its conventional volume control.
 
the volume knob on my 112x works fine by hand or by remote
but it makes a creaky noise - only when you use the remote
what is that noise?
and how can i fix it?
thanks
Jim
 
MJS said:
Sorry guys, I don't touch these. I believe the problem is due to the rotary encoder and electronics that read the position of the volume control. Shortly after introduction those electronics became obsolete. It really isn't one of Naim's finest products. You are much better off with a 102 and its conventional volume control.
Click to expand...

It isn't a rotary encoder, it's a conventional pot, that outputs a voltage, this voltage is then used to control the volume ladder analogue switches. I guess an ADC reads the voltage and then a processor drives the volume control. I had this happen on mine once and just cleaning the pot worked.
 
JimDog said:
the volume knob on my 112x works fine by hand or by remote
but it makes a creaky noise - only when you use the remote
what is that noise?
and how can i fix it?
thanks
Jim
Click to expand...

I'm guessing it's the motor / gears driving the volume control as that will only be active when using the remote. Not sure whether they are plastic or metal, but lubrication could help, if it's possible.
 
Andrew L Weekes said:
I'm guessing it's the motor / gears driving the volume control as that will only be active when using the remote. Not sure whether they are plastic or metal, but lubrication could help, if it's possible.
Click to expand...
Thanks Andrew. Yes, I guessed it must be a motor operated by the remote volume control.
But I'm a technical/electrical moron.
I've never even opened a hifi casing.
If I try to do it I'll probably break something.
So I'll try to find someone to help me in the engineering dept of Lancaster Uni where I work.
(I emailed a Naim service place in Sheffield about it and he didn't reply - which suggests it does not make sense as a commercial repair.)
Please let me know if there are any obvious pitfalls or things not to do when opening a 112x.
thanks
Jim
 
JimDog said:
Please let me know if there are any obvious pitfalls or things not to do when opening a 112x.
thanks
Jim
Click to expand...
If it's the same as a 112, there's 4 screws underneath holding the lid (one with a star washer for earthing) and a hidden smaller screw, under a plastic hole plug at the front centre of the bottom case. Remove that plug and loosen (not completely remove) a cross head (Philips?) screw that secures the front edge of the top panel to the front panel. You may find it easier to completely remove the screw the first you open it, then the top panel will just lift straight off. Refit the screw a couple of turns once the lid is removed. You will need a suitably sized and length screwdriver for this.
 
Thanks Andrew - yes that's the exact layout of the base panel. The plastic hole plug does lift out with my fingers.
I haven't tried removing the top cover, but know how to do it now.
many thanks
I suppose I need to find a friendly electrical engineer before I go any further.
 
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