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NAC 12 restoration project

MJS said:
I'd remove the older solder first.

This is serial number 0054. Probably 40 years old!
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Thanks Mark. What a rarity! Mine is 0515 (from 1976 I presume).

Your pic shows that the input selector is the same as on version 3. Then mine NAC 12 version 2 is now restored to true original spec.

P.S. Mark, I e-mailed you about my dead 110, please check your inbox. Sorry for offtopic.
 
yurivv said:
Olli,



Hope I'm right. Sorry, I'm not very good at painting. Pic is clikcable.
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What about this earthing thing? What should I do? Can I just solder some wire to that point and the other end of wire to "turntable" earthing screw or something? Sorry if this is a stupid question....:p
 
Olli I said:
What about this earthing thing? What should I do? Can I just solder some wire to that point and the other end of wire to "turntable" earthing screw or something? Sorry if this is a stupid question....:p
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Olli,

It impossible to tell by this picture fragment. You have non-standard wiring so that the earthing could be done in other ways. I'm sure Mark would pay attention to obvious layout errors, so just solder back the resistors leg and listen. :cool:
 
The earthing from that soldering point must lead to volume pot, but I see from your pic that green wires (these are earthing wires) come to volume pot from another soldering point. This is most likely done on purpose.
 
Ok now it is working as it should be. I also checked over all the soldering joints. I have some tants. The yellow ones. Maybe I should recap at least 729/1 boards at the same time. Is it necessary to change the axial s.l.c.e. caps? Or something else on the boards?
 
Olli,

Are you using a complete set of 321/729 boards from NAC 72 instead of original 321/324 boards in your NAC 12? Are they fully compatible with 12 main PCB? I'm thinking of experimenting with these boards from my 72 and NAC 12.
 
yurivv said:
Olli,

Are you using a complete set of 321/729 boards from NAC 72 instead of original 321/324 boards in your NAC 12? Are they fully compatible with 12 main PCB? I'm thinking of experimenting with these boards from my 72 and NAC 12.
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I think they'll work fine but I prefer the 321/324 combination in the 32 and 12.

My 2 cents.

Mark
 
yurivv said:
Olli,

Are you using a complete set of 321/729 boards from NAC 72 instead of original 321/324 boards in your NAC 12? Are they fully compatible with 12 main PCB? I'm thinking of experimenting with these boards from my 72 and NAC 12.
Click to expand...

I am now trying Class A serviced latest boards from my Nac 32.5

They sound quite different to Class A serviced original Nac 12 boards.

Yes 321/729 boards are compatible with Nac 12. I just don't like it that way.
 
Now that this (new) Nac 12 is working and all the soldering joints are fine....it sounds grrreat. Is it a difficult task to get Headline working with it? It seems that the wires have been removed. Is it only two wires that I should solder to din tape connector pins? Where the other end goes? I have good (probably for this task?) Mogami 2549 that I could use.

Sorry yurivv to ask all these questions on your thread. I can start another thread if you like?
 
Sorry, I did not have time to read everything that was written here, as we have some guests today.

Olli, I think there is no need start a new topic.
 
Olli I said:
I am now trying Class A serviced latest boards from my Nac 32.5

They sound quite different to Class A serviced original Nac 12 boards.
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This is curious. Whether Class A used the same components for servicing? Which version of the boards in your 12 and 32.5?

I have 32.5 on loan, so I will try its boards.
 
Olli I said:
Is it a difficult task to get Headline working with it? It seems that the wires have been removed. Is it only two wires that I should solder to din tape connector pins? Where the other end goes?
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Olli,

Is your Headline equipped with DIN or RCA sockets?

No, it's not a difficult task. Post the whole internal photo of your 12, I will point out where the other end goes.
 
Gaius said:
I think they'll work fine but I prefer the 321/324 combination in the 32 and 12.

My 2 cents.

Mark
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Thanks Mark. But there is always a curiosity. :) I always wanted to know what gives the unique sound of the 72 - the boards, the main PCB or the combination?
 
Here is the repair work that I done. I took the wires through the circuit board which came from Noble pot and soldered them on the back of the circuit boards. In my opinion that is a good solution because those are very heavy resistors. Now the wires are securely on their place. I also repaired the soldering joint that Malcolm pointed as a "not so good soldering".

rvbkp2.jpg
 
I took about twenty pictures and this is the best I got....I am not very good at photographing. Maybe you can see here anyway where the wires are connected.

Headline is equipped with din-socket. Nac 32.5 has 321/5, two set of 324/7 boards. Nac 12 has second and third revision boards. I forgot to check that. I checked the Class A invoices and the same components were used to service both amps.

2aj11km.jpg
 
Here is a picture on the back of the unit. There is also a preamp out through rca connectors. I don't use that option though.

t4tdol.jpg


One Idea would be to drill a hole and connect a new din-socket only for Headline use?
 
Olli,

Please take a look at the pics.

Here are the pins carried line out signal

d392c6768db2.jpg


Here is the rotary switch. This is so-called 3 way 4 pole rotary switch.

e8b8d2ab3be5.jpg


1. Locate 6 free "outside" soldering tags, they are near two inside soldering tags where purple and orange line out wires soldered (they must be at the left side of the switch). Note that yours rotary switch is rotated anti-clockwise slightly from strictly vertical position as pictured on my schematic!

2. Solder links between two pairs of the outside tags. So line out signal will be routed to tape out when phono or tuner inputs are used.

3. Solder wires to one of this tags per channel. The other end of each wire must be soldered to one of the DIN tape out tags.

4. Note that one pair of tags on the rotary switch must be unused.

P.S. Sorry again, my painting skills are even worse than my English. :(
 
Olli I said:
I also repaired the soldering joint that Malcolm pointed as a "not so good soldering".
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That wasn't me! I'd never comment negatively on another chap's work, for fear of having my own criticised.
 
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