NAC72 Selector Switch knob not working...

OK - Was able to remove the little screw which definitely has one half of the head missing that must have broken off - Anyone point me to where I would find an identical replacement screw as I would assume its a simple case of replacing this now and I should be back in action?

Cheers,

Vin.

Just reached out to the top man 'Chris West' here in the US of A in the hope that he can point me in the right direction, as I would assume I can't just simply walk into a Home Depot or similar hardware store and easily find this tiny locking screw!!! lol 

It might prove difficult to ID the size & thread profile with an old unit like a 72, it might be BA it might be AF,  it might be metric.  Phone a Naim service shop like Chris West as he should know the size & thread.  Or if you have a local old style electrical/TV/radio service shop & even if they don't have the screw they will ID it for you & then you can buy a small pack from www . 

I find this very odd. A metal screw broke..? What broke it....?  

This is a remote switching unit, I think....? Which Naim would have bought in, from say, Alps. Could be a tricky one.....

It's a small grub screw that screws through a small metal fixing plate that nestles within the plastic selector knob.  I don't know the size of the screw but if you ask him then I'm sure that Chris West should be able to advise on Monday.

Spot on Richard!

Have already reached out to Chris and hopefully we'll track this little grub screw down so I can get my NAC72 fully functional again.

@ianrobertm

Not sure what broke it - I guess after 30 years, things wear out and break....

Hello All...

Just wanted to give an update on what is proving to be quite the saga and unfortunately, I am still without a proper working NAC72.

Called Naim in the UK and basically was told that it's not a part that they carry (which was not surprising) and that no one there had any information on the size/specs of the screw. I would have thought that they would have some design document somewhere to be able to provide this mysterious screw spec but alas...

I visited several hardware stores including RadioShack which unfortunately is closing down - I got fairly close with one hardware store (Sears) which had metric "setscrews" (I assume the American equivalent of "Grub" screw!) and it looks like the size is going to be around an M2 but that didn't seem to fit properly as I was able to push the screw though. An M2.5 screw was also a little too small so maybe the next size up??? Of course, they didn't carry any square nuts that I could potentially convert over to a standard size rather than metric - so no joy there either...

I also spoke with Christ West earlier today who is kindly trying to help out - he believes he has a complete switch that he can sell me so that will hopefully get me out of this pickle. However, I am astonished at how hard it is to get information on this part and in being able to find a replacement  that probably shouldn't cost more than $0.50!

Oh well, such was the design of this thing back in the day and I'll have to keep looking unless Chris can save the day for me... 

Vinbob, I think that the problem may be that it was supplied as part of the complete knob assembly rather than as a separate part.  Naim would receive a batch of knobs along with a bag of fixing plates and screws.  As such the screw spec would not be officially recorded.  And unless you have one spare to then compare against, it's just guesswork.

When last I enquired about 4 years back for a NAC42 knob Naim just had a few knobs and not the fixings, which was fine if you still had your old fixings.  But it does also suggest that maybe your issue was not an isolated one and replacement fixings were given out without their knobs.

Anyway, hopefully Chris West can come up with the right part.

Thanks Richard and agreed. I would happily purchase the complete knob if one was offered by Naim.What is real interesting and worrying at the same time, is that there are a lot of people out there with these Olive (and CB units) that eventually, are going to run into the same problem - one would think that these parts would be somewhat readily available...unless I am missing something...

I'll let you know what Chris comes back with and thanks for the feedback...

Cheers,

Vin.

Vin,

spares have been kept for many years but they've been long out of production.  Naim had lots of spares but at some point things eventually run out.  Remember it's 14 years since the Olive control knobs were last produced and over 25 years since the CB knobs were produced.

But of course plastic knobs subjected to constant stresses will eventually fail, particularly if the plastic starts to go brittle with age and atmospheric exposure.  This has started to happened to a NAC12 of mine, where one knob has got a split from marginally over tightening the grub screw. Sadly those little grey knobs for the NAC12 and original NAC32 are also long gone.  The good news is that you can get hold of a number of different substitutes, often rather nicer too, particularly when made from aluminium.  I have a set of KILO knobs standing by for mine when the plastic knobs eventually fail and they actually look and feel rather better than the originals.  I'm seeing more and more NAC12s with these KILOs onboard and they look like they were there all along. So it's not all bad news...

Understood my friend and totally hear you on the aging of this stuff, as it has been about 25 years since I purchased my NAC72 and I still love it!!!

Now, I am very intrigued by the KILO knobs - can you kindly point me to the ones you purchased for your amps (I assume they would be compatible with the NAC72?) and I will look into those as a plan B?

Cheers,

Vin.

Vin,

this is the KILO knob in question.  It's ideal for the NAC12 and original NAC32, both early bolt-down pre-amps.

To comply with forum rules I can't post a link here but a quick search in the usual places should bring up a few places that have them.  

However, you'll need something different (and a bit bigger) for the NAC72.

Here's a link to forum member Yurivv's post about the KILO knobs on the System Pics thread;

https://forums.naimaudio.com/to...25#31273966709072325

Ahhh... yes, those do look a little on the small side. Bugger, I thought we had a good plan B there!

Well, I can always look to find an equivalent as this is a great idea if I can't get the original one working again. I measured the shaft which is around 5.96mm or there about. So I have that info ready to go to match up with a different replacement knob... 

Vin

I've just took a look at the selector switch on my 62. From the diameter and pitch the screw size is 7BA.

There's a small chance it is M2.5, but it doesn't look like a metric thread to me and I'm sure Naim would use a British thread.

If you search "7BA Slotted Grub Screw" on a well known auction site you may find what your looking for.

 Hi fatcat - I think you may be onto something here. I just had a look on Google and they certainly look like my broken one. The only snag, is that they are cheap enough for a pack of 10, but then its 5 times the cost to ship from the UK and it may end up not being the right screw?!?! lol

When I showed my screw to a hardware store person, he seemed to think it was a metric screw - however, when we tried both an M2 and M2.5 screw, they seemed slightly smaller and I was able to push it through the square nut that the screw goes through connecting with the switch shaft.

I guess the ideal situation would be to find a store that has a few different variants to match and try but if it definitely is a 7BA, then I may just go for it at this point. Would a 4BA be thicker or smaller in diameter?  How does the number work before the BA - what does BA stand for?

Sorry for the many questions and thanks for the help!

Cheers,

Vin.

Well, sorry, only a suggestion, why not consider to use not metallic screws but a teflon or delrin (stiff plastic), hobby shop have of different diameter, you can select ones and thread it into the hole.
Of course, as last option.

@vinbob - If you keep trying, I believe you will find a suitable screw (!!). Its just an engineering part - so its out there, somewhere. Regarding costs, whats your 72 worth...? Compared to the cost of say 10 screws...? Worst case, someone in the UK might help you.....

IanM

Vin

I took my micrometer to the screw this morning, it is actually 6BA. The 6BA is 12 thousandths of an inch larger than diameter than 7BA.

BA stands for British Association, the smaller the BA number, the larger the thread.

Moderated Post:  FC, I appreciate you are trying to help but forum rules are firm and there are no exceptions under any circumstances, so I've edited your post.

Confirming the micrometer reading, there was never a chance this would be 7BA because the sizes in regular use for electronic parts back in the days I used to make things (with valves in to start with) it was 0,2,4,6 and 8 BA which were used - occasionally 10BA.  I must have screwed and unscrewed thousands over the years. But I never saw an odd number BA screw thread in practice. There are lots of 6BA grubs crews on the well known auction site.  I wouldn't go for aluminium because that's a bit soft. Steel or brass should be fine. If you can find one with a hex socket head so much the better.

best

david

Thanks for the help everyone - we are getting very close!!!

I will look to track down the 6BA grub screw either locally or will order from the UK. Truly appreciate the efforts from fatcat in measuring to confirm the size, and the additional confirmation from David.

BTW, what's with the moderated post for trying to help someone out...?? Can someone please explain...? 

I hear ya Ian... Not that I wouldn't order them given the cost, but I just thought it was funny that I would have to pay 3-4 times than the actual part.itself....

It's in the Forum Rules - see the sticky at the foot of the featured section of topics in each part of the Forum.  No linking to live manufacturer's or commercial sites. It's Naim's forum so it's their rules that we all have to play by. They don't mind references to manufacturers etc, as demonstrated by endless discussion as to whether Naim kit us better it not than other manufacturer's kit, just the live links.

best

David

And the golden rule: strictly no sales or wanted ads, including offers of free stuff etc..

Thanks for the clarification gents. I guess in this case, it was the 'offer of free stuff' that caused the moderation correct? 

@VinBob - So the part is cheap....??  And you are a long way away.....

In a former colony. I rest my case.

I sometimes wish that the shipping cost from the US was as cheap is it is from Europe.... Or as fast.