Bolt down NAP160 bolt size ?

I've got myself a bolt-down NAP160 & need to get inside but some bugger has already tried & rounded off the heads on the bolts ! Not a big deal getting them out but I'd like to replace them.... Does anyone know the correct size replacements ? I thought M4 x 8 but not sure.

Thanks for the help

 

M4 x 8, countersunk with Allen key head,

malcolm

Correction: M4 x 6, but I don't think 8 mm would be a problem.

 

Spot on Malcolm ! Thanks for that.

James.

 

James,

I spoke too soon but have now been to measure them and they are M4 x 6, although I doubt if 8 mm ones would create any problem!

These, from eBay are M4 x 8:

http://cgi.ebay.co.uk/M4-x-8-Counte..._Material_Nails_Fixing_MJ&hash=item2a0a005783

but a quick search has failed to find any M4 x 6 in black,

malcolm

 

Hehe those are the exactly ones I bought five minutes ago !

I also need some new ones for a NAC12 as they originals are rusty - Just on the off chance you might know ?

James.

 

The ones in the NAC12 are M3, again countersunk but with Phillips or Posidrive heads. I remember that there were two different lengths but I can't get at them all without removing the NAC12 from the rack. The length didn't seem to be important. The one I have removed is M3 x 7 so I think M3 x 8 would be fine for them all,

malcolm

 

Your a gent Malcolm

Thanks for the help, James.

 

No problem James, glad to have been of help. I've recently serviced a BD NAP160 which is for sale in the classifieds forum and a NAC12 that I'm keeping for now. If you need more help just ask!

p.s. I've bought screws from that eBayer before and was very happy with his service and products,

malcolm

 

Hi,
whilst on the subject of bolt sizes - does anyone know what size the bolts on a 250 holding the heatsinks to the case are?
Thanks,
Pete

 

M5 with a 4mm hex key needed...if you mean the big ones going right through the case. If you mean the smaller ones holding the heat sink to the inner tray they are M4 again....

 

Thanks Neil, I appreciate it.

 

Yes I did notice that in the classifieds, a bargain if you ask me....Recently paid £390 for my BD NAP160 / NAC 12 which are both unserviced & a bit tatty.

I intend to pretty much replicate what you have done to yours - The S/N on mine is 492 which dates it to '74 I think so parts / build may be slightly different... I'll have to take a peek inside & see.

How are you finding the NAC 12 ? Its pleasantly suprised me so far after pulling the MC boards & running in a few days.

 

Firstly a word of caution. If you are replacing the feet on the 160, which is a good idea on a product of this age, be aware that the earth strap connects to the chassis through the bolt attaching the foot closest to the mains input socket. I didn't realise this and removed and replaced the foot leaving the earth strap and nut floating around inside the case. Luckily I spotted the error before any damage was done.

Serial number 0492 dates your 160 to the second half of 1976.

The NAC12 is an excellent and under-rated pre-amplifier. The weakest points are the basic quality controls. You owe to yourself to replace the volume control with an Alps Blue (http://uk.farnell.com/alps/rk27111220k/potentiometer-20k/dp/1191722?Ntt=1191722) or better. If you don't need the balance control, replace it with two fixed resistors. If you do need it, find a better potentiometer. I also replaced all the sockets on the rear panel.

There are three versions of the 12. Version 1 has all the components on a single board (with the possible exception of the phono boards) like the NAC42, Version 2 has six daughter boards (2 x 324, 2 x 321 and 2 x phono (322 or 323)) with the relay circuit on the motherboard. Version 3 also has the relay circuit on a 325 daughter board making seven in all.

Versions 2 and 3 are very little different to the NAC32. The performance can be further improved by replacing the 324 boards with the 729s as fitted to the NAC72.

You will probably find that the tantalum beads are all rated at 25 V, Naim had a program of replacing these with the 35 V types when units came in for service.

I have a future project to fit individual regulators for each board. The layout makes this extremely simple. A strip of regulators would easily fit onto a side panel and you could feed in 37 Vdc or so from a printer brick or, alternatively, you could wire out the pre-amp regulator in the 160 to get a similar raw dc supply.

malcolm

p.s. Having checked I remember that the NAC12 Version 2 has different edge connectors to those used in the later preamps so more modern boards will not fit. The Version 3 has the same edge connectors as the NAC32 - NAC72 and is, therefore, somewhat easier to upgrade.

 

Fantastic info Malcolm !

It turns out I bought mine from this forums own RCook...

From your decription my NAC12 is a Mk.2 but not entirely sure - I'll be starting work on them Wednesday anyway so I'll have a look then.

First job is to make a parts list !

NAC12 :

20K Alps Blue pot.
Elma selector switch
Not sure what balance pot to buy (would rather not bypass it)
Recap all boards
Replace the old & decrepid DIN sockets with some nice new ones
Fit inline attenuator (couple of R's) to the tuner input
New feet

NAP160 :

Kendeil psu caps
Full recap / maybe bypass the preamp cap with a film or teflon
Disable SOA - May need a wee bit of guidance when the time comes !
Fit some new 4mm Binding posts as current ones need a wire brush & some elbow grease...
Bias / DC offset
New feet....Also need to replace the power switch bulb.

Looking at getting a mate of mine that owns a car bodyshop to sandblast the cases & fill / respray them, need to get some preamp controls machined too... One of mine is cracked

After that little lot They will be sorted for another 20 years all for the price of a s/h nait5i ..... I wonder which would sound better ?

If you can think of anything else I'd be glad to add it to the worklist !

Cheers, James.

 

The 12/160 would beat a 5i any day of the week for me

My 160 already had a film capacitor across the 3,300 uF electrolytic in the pre-amp supply.

If you're having the re-spray I'd be interested in having the four main panels of my NAC12 done at the same time.

I replaced the BNCs on the phono input with RCA phonos which fitted the holes exactly. Are you keeping your phono boards in, or by-passing them to give another line level input?

malcolm

 

I couldnt agree more, new Naim just doesnt do it for me until you get to the £££ level.

I removed the 323 boards & replaced them with 328's ... I know they are apparently terrible but they are O.K for the minute & buy me an extra input. The other four boards I havent bothered identifying yet.

I'll let you know once I've seen him & get back to you although I doubt he'll charge anything for spraying / refinishing them....never has yet anyway.

Cheers, James.

 

Take out the dreadful 328s and replace them with simple link wires - instant improvement. I can let you have a couple of link wires but they would only suit the version 3 edge connectors. I'd need to see the connectors on a version 2 to suggest the best way to go.

malcolm

 

Okay, sounds like something else to do ! I'll take a few pictures on Wednesday & get your opinion on the best approach.

Looking at the 323/3 boards the pins look identical to the ones in the attched picture.... So possibly a Mk.3 ?

Cheers, James.

 

Its quite handy to read all in one place so....

Received the bolts & replacement bulb today so started work on the amps..... All of the top cover bolts on the nap160 had rusted and already been stripped so it was fun getting them out, only took 2 hours ! Anyway upon opening it I found a couple of interesting things.Firstly, the PSU filter caps are BHC & dated to 1987 so maybe this has been recapped in the past ? All of the tants in both pre/power are rated at 35v too, i'm sure the originals are supposed to be 25v might be wrong though.

However, onto the nac12..... As you can see in the attached pictures it is a Mk.2 with the 6 daughter boards (2xNA112 / 2xNA114) I have now removed the evil 328 cards & fitted cartridge tags in place on the pins which fit perfectly giving a real improvement in SQ when using the phono input.

I've sent Naim an email to find out if they has been serviced in the past & just need to order the new pots / connectors / caps etc.....

 

Hi James,

you'll need to host the photos somewhere in order to get them up on here!

If the psu caps are 1987 and the tants 35V the amps have both been re-capped. Best of luck with Naim, they are very good with stuff built after 1982 (when they moved to Southampton Road) but get a bit vague with anything earlier. They should have a record if they did the service. Must have been a caring first owner if they were re-capped after just eleven years.

The NAC12 is definitely a Version 2. Did the 328s fit easily onto the pins?

Carry on with the good work,

malcolm