NS1000 Level Controls Misbehaving

[sonata149]

I wrongly posted a similar thread in the Full Range forum.

For some time I've been hearing the left speaker down in volume. Today I tried to increase the mid-level control and to my amazement and disappointment I noticed that halfway between the 'Normal" and '+3dB' positions the mid-range speaker and tweeter were cut off. Moving the control further down (or up) music was coming out again. Compared to the other speaker the volume level is still less 'energetic'.

A member (Thanks Hennie!) said he had the same problem, claiming it's a common problem with the NS1000. The attenuators are not of the same quality as the rest of the components, so he replaced his with equivalent fixed resistor L-pads.

Reading over several posts, today I checked to make sure that the mid- and treble speakers are OK. I used a simple 1.5V battery and they both made 'noise'. That solved a lot of problems because they cost a lot and are scarce. Last year I changed the crossover capacitors (after reading the thread here) but I still have to look at that for possible deteriorated joints (?). So far my mind tells me the attenuators may be defective and need to be looked at.

I'm reluctant to believe that the original attenuators are crap. They are Noble (!) after all !! Is there a way of restoring / cleaning them? Has anyone done it before?

Thanks for any help and suggestions.

[Shaun]

You could try simply exercising them a bit by tweaking the knobs back-and-forth a few times. This often cleans up the contact.

[sonata149]

Thanks Shaun, yes what you say is true. I already noticed an increase in the sound level, but still not up to the other speaker. As you mentioned cleaning the contacts do you know whether the attenuators' contacts in the ns-1000 can be reached?

[event horizon]

I'm pretty sure that the L Pads are wirewound & not carbon tracks, though i haven't looked inside mine to investigate (i'll do that shortly ).

You might be able to get them working properly again by turning them up & down as suggested by Shaun, maybe some switch cleaning lubricant applied at the same time will help. Something like "super servisol" though i have no idea of the equivalent elsewhere.

Failing that there might be a way (though rather unorthodox) of sorting them out, though i'd use it as a final attempt. You'll need a glass of coke (yes cola) & a load of de-ionised water. Soaking in the cola will rid the things of any oxidisation but they'll need a thorough wash in the de-ionised water afterwards to rid them of the coke. Allow to dry & they should then work. Please note that i have never tried this, but if you saw how coke strips oxidisation from copper coins you'd realise it should work


Just had a look at one of them & yes, they look to be wirewound. My guess is they are oxidised.

[Shaun]

Originally Posted by sonata149

As you mentioned cleaning the contacts do you know whether the attenuators' contacts in the ns-1000 can be reached?

Regrettably, I don't own a pair any longer, so I can't event have a look. Event Horizon's suggestions sounds like what was mentioned in this thread. Perhaps it would be a good idea to post your question there.

[event horizon]

I looked at one of the attenuators earlier & they are a pretty solid block of ceramic. There are gaps however where switch cleaning lube could be injected in. These things appear to be nearly solid ceramic with an outer copper coating that may well be a shield, no idea.

You'll be able to inject switch cleaning lubricant or soak them in something as i mentioned. Just make sure that if you soak them you clean them out with pure water (de-ionised, used in lead acid batteries or irons) afterwards to thoroughly clean them out. No point in contaminating them more is there

[sonata149]

Thanks Event Horizon and Shaun for your input. I meant to ask Event Horizon, as he clearly has a pair of these speakers, whether the contact cleaner solution is placed on the wirewound tracks through the small slots (openings) adjacent to the 4 lugs coming out of the attenuator barrel. If yes, is contact made to 4 sides (tracks)??

As I'm not sure I can find Super Servisol locally, I was thinking whether I can use the 2-step Cramolin (Caig Labs. Inc) treatment which I bought many years ago from Old Colony Sound Lab in the US. Step 1 is the anti-oxidizing lubricant, cleaner; the 2nd an anti-oxidizing lubricant, preservative. The liquid is applied by brush.

What do you think?
Joe A

[David Gatti]

They're probably corroded. I'd be bypassing the attenuators altogether.

[event horizon]

Hi Joe, you'll not get a brush in there as you can see There are two gaps as you mentioned with the 4 contacts & two of those are connected together making 3 contacts total. Yes i do own some, in fact i bought 3 pairs of them

Do you have access to WD40? This is another alternative to super servisol though not as good imo, it still cleans up dodgy potentiometers so should be ok on any wirewound resistor.

There will be a wiper & resistive track in each of the gaps (segments) of the L-Pad, you'll need to get both of them clean to bring the thing back to standard.

I'm sure you must be able to find some kind of switch cleaning lubricant wherever you are, i just don't know what it'd be called. Google could be your friend in this instance

Sorry fella, clutching at straws in this instance.

Bests, Mark.

[morksbeanbag]

Originally Posted by event horizon

Hi Joe, you'll not get a brush in there as you can see There are two gaps as you mentioned with the 4 contacts & two of those are connected together making 3 contacts total. Yes i do own some, in fact i bought 3 pairs of them

Do you have access to WD40? This is another alternative to super servisol though not as good imo, it still cleans up dodgy potentiometers so should be ok on any wirewound resistor.

There will be a wiper & resistive track in each of the gaps (segments) of the L-Pad, you'll need to get both of them clean to bring the thing back to standard.

I'm sure you must be able to find some kind of switch cleaning lubricant wherever you are, i just don't know what it'd be called. Google could be your friend in this instance

Sorry fella, clutching at straws in this instance.

Bests, Mark.

They aren't actually wipers and track at all and they are far, far from being in any way poor quality. The noble L-pads are by far the best quality L-pads I've ever seen. I've stripped a few of them down (practically impossible to reverse so don't do it) and inside they have gold plated copper wire windings with beautifully plated solid copper wipers. Changing them out for anything other than a single very high quality resistor would be a downgrade. Buying something of their quality now would cost a small fortune.

I have got a few spare but you can sometimes pick them up on ebay in the U.S for $100 or so. I bought whole crossover units as I've been designing and making some brand new PCB's for the NS-1000/1000M to fit in place of the existing one which allows you to use the very best grade caps possible for ALL sections without having to do anything other than a few snipping and crimping jobs. I'll post a pic soon of them as I have them ready now.

Some 'Deoxit' cleaner is supposed to be very effective for L-pad cleaning and is non corrosive unlike IPA. Please(!!!!!) don't use coca cola inside them.

If you really can't get them going then send them over to me and I'll take them into work as we've got everything there for getting anything hifi back to peak condition. I won't charge a penny for doing it for you as I love getting NS-1000's to sound their best.

kind regards

Ben