NAD 1972 Model 1986

Central Scrutinizer

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Traded a pretty cool Les Paul for this 1972 1986 Bass circuit amp.
I think we both did OK in our respective trades.

Do not know everything about the originality of this other than it has had routine service and caps replaced as needed. Have not received it yet, the enclosed pictures are the Sellers/Traders.

There is some pretty cool recent history associated with this amp, which I will go in to detail after I have it for a detailed review and tone report.

The pictures to my novice eyes look pretty good, I do of course defer to the experts here at the forum to ascertain the originality and completeness of everything. (Please be gentle). Lol 😆

The price tag on the amp handle is a few years old per the Seller.

Thanks in advance.




74B4F172-68FA-4F24-8873-84101AF47728.jpeg C30618B0-7AF8-4C39-84B4-9A5929A32327.jpeg 41112E5A-A69F-4CFF-BFA5-AC0C93E2A08E.jpeg 2463B099-8C5E-45BF-8C19-D9C9844042DB.jpeg 665B6B7A-727C-492D-BE24-101B630E3019.jpeg A420483B-9991-4BF8-871F-1F2F8E14186A.jpeg 82B8BF67-0155-42C6-A4DB-3ADF3CA178F1.jpeg 37A18A18-3A90-4AF4-A9AE-F066457DFB74.jpeg 14ACFF15-4928-492B-8362-D2CE43FBE249.jpeg 0A6EF5A6-59A1-491C-AC68-61176C20D0DD.jpeg
 

Central Scrutinizer

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Nice looking amp. Looks pretty good/original to me. The power transformer isn't original and is orientated incorrectly, ie. 90 degrees out.
Thanks.

I thought the wiring looked like a rats nest under the transformer!

Will get that corrected.

Thanks again.
 
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AndyD

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Thanks.

I thought the wiring looked like a rats nest.

Will get that corrected.

Thanks again.
The wiring can easily be sorted. The output selector wants looking at as well. Very minor points. Cosmetically it looks fantastic. As for the power transformer, you can live with it, no problem, or source an original (pricey) or get a Marstran reproduction which are excellent. Either way, you will have a great sounding amp, thats for sure. Congratulations,
 

TAZIN

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Aside from what has been already mentioned the majority of the circuity looks original. Some additional things I noticed are:
The bias circuit has been updated with new caps along with a couple of resistor changes including a new diode.

The snubber caps for the rectifier has been replaced.

Added 1K/5w screen resistors on the octal sockets.

The Indicator light has been serviced.

Not sure what's up with the speaker output jacks...Never seen that many fiber washers used before.

Also perplexed by the extremely long replacement screw & nut for the mains filter cap clamp....

EDIT: Forgot to mention that you should make sure that the bias feed is hooked up to the hot side of the Standby switch.
 
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playloud

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Very clean! Nice work

Can't really add anything other than what has been posted above. I imagine the PT orientation might cause issues at such close proximity to the OT.
 

Matthews Guitars

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I note that the chassis plating is in unusually pristine condition. It has been kept in a fairly clean environment all along,
and hasn't been handled much, either. (Fingerprints will cause corrosion of the chromate plating, making for permanent fingerprints.)
Have the power transformer reoriented immediately. That's actually a fairly serious issue. Transformers that are arranged in the same plane as each other will crosstalk very easily and that can lead to a very unstable amplifier and oscillations that may be ultrasonic.

That should never happen. Anybody who has any business working inside a tube amp should know about transformer orientation. That should be "first day of school" knowledge at the local electronics school.
 

Central Scrutinizer

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Anyone have an opinion on this brand of Power Transformer for the amp?

(If a replacement needs to be used).


Pacific Audio Magnetics

Marshall 50 Watt Power Transformer
50 WATT, Drake, JCM800, JMP 50W
Drake PN: 1202-324
[PAM-PT-50-36R]
$147.00
 

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