sad NAD 216 THX wants my attention :-)

[Bert 1100]

I bought this 125 WPC NAD for a very low price, advertised as "makes a very loud hum"
The faceplate has been sanded and looks pretty bad, the rest is in more or less good shape.

Before plugging it in I opened it, and found it looked nearly untouched, apart from the relay that had been replaced. The relay was not of the proper type and had been taped to the back of the amp, with wires connecting it to the board.
And in time the relay had come unglued and had fallen onto the speaker terminals.
I think that's where the hum came from, who knows.

Anyway, I moved the relay out of the way and fired it up on the DBT.
And basically it all works nicely
So I've decided to give it a full overhaul.












So first thing was to take it apart, and make a parts list.
I will be replacing all the caps, the amp is around 20-25 years old, and some caps look bulged.
There is a mix of Nichicon, Lelon and some no-names, but I think they are all original.

 

[Bert 1100]

Here is the board after the previous relay "repair"





A couple of lifted traces, nothing too bad.

First the boards got cleaned with alcohol and then some sort of Windex.
And as usual acetone to soften the old glue that was holding the big caps.

I'm using Nichicon KS for the main supply caps, same rating as the originals, 6x 4700uf at 80V, they are exactly the same size as the originals, same snap-in as well, nice.

The rest of the power supply I've used Nichicon PW. And three film caps to replace the 1uf and 0,47uf lytics.










This is one of two 100V / 100uF caps : half the capacity, ESR 42Ohm and 33% Vloss




And this was the state of the rca input connections, the hum could have come from there as well





Somehow I messed up my parts order and forgot half of the caps for the amp boards So they are not yet done, but at least they are clean now !




For the faceplate, I first thought I'd give the original a good brushing and leave it raw aluminium.
But then I thought, wait, I have some beautiful walnut and good woodworking skills, so that's the idea for now.

 

[Goldie99]

Nice find, and nice work ! I'll follow with interest

Is that Planquiri - Suisse ?

 

[Bert 1100]

Is that Planquiri - Suisse ?

Hello Boston UK, yes Suisse here

 

[Goldie99]

V. nice area, as long as you don't need a job 12 months of the year...... or you don't mind commuting !

I lived in Schoenenberg (ZH), then Founex (VD), for 12 years, in fact both my daughters were born there - one's still living / working in Lausanne now.
I doubt I'll get back again (to live there), but I 'top up' regularly on the Raclette, Fondue, and CH wine. Fond memories & a great country !

 

[Bert 1100]

s long as you don't need a job 12 months of the year...... or you don't mind commuting

I live in Planquiri, 1100 meters above sea level, and work 12 months a year in Sion, 10km away and 600 meters down in altitude.
For nearly 2 years now I use exclusively an e-bike, even in winter with temps down to -15 Celsius. In winter I use spiked tyres

By car it used to take me 35 minutes there and back, by bike it takes me 45 minutes there and back

Living in Lausanne AND working in Lausanne, you can easily spend more time than me commuting. And in Geneva it's much worse.

 

[NAD80]

I would replace the pots with a Bourns sealed pots. Will hold the set point better. Like the cap meter. 42ohms ESR real bad cap. Nice save on the Nad 216. Have 3140 integrated amp. Love the Nad watts. Checked the Service Manual just one pot in each channel. One thing I would do is to put shrink tubing over the heat damaged wiring. Too close with the soldering iron I guess. Make sure that both slide switches get cleaned. Hope all the parts arrive quickly, but take your time when replacing the caps, take plenty of pics. Can't wait to hear how this turns out.

 

[Goldie99]

1100 meters above sea level..... and in Geneva it's much worse.

Yes. I really enjoyed the 700m altitude in Schoenenberg - just high enough to get above the Autumn / Winter mists & cloud, and into the sun. Work all day in the mists, and come home to evening sun, beautiful ! ... and you're right, I indeed worked the other side of Geneva, next to Cern, so the commute was often over an hour, sometimes over 2 when the car show was on, but I had to be near the Airport.

Back on the NAD - not sure how bad the protection wiring changes are in yours, but if it helps, the following link has info re. the Omron equivalent relay, in case you can get it back in the proper location.

https://fittingmedia.wordpress.com/2013/01/16/nad-214-poweramp-refurbishment/

 

[Bert 1100]

in case you can get it back in the proper location.

Thank you, it's already back as supposed, with a new relay

 

[Bert 1100]

So, the amp is all done, all I need now is to make that nice walnut faceplate I have in mind...
It all works as it should and sounds pretty good, with a lively dynamic sound.

There is one small issue with the idling current though :
On the right channel amp board, one of the output transistors had been changed (not by me) along with its emmiter resistor.
The originals are Sanken 2SC3519 "Y" and the replacement is a Sanken 2SC3519 "O"
This replaced transistor is the one with the test points for the idle, and adjusting this one to 18mV makes the other ones on this channel run at around 30mV, so this side's heatsink gets warmer.
So what I did is measure the idle across all transistors on both channels, and made it so I have equal heat on both sides, with a minimum of 15mV for that one replaced output, and up to 28mV for some.
I don't think it's a problem really, there is plenty of cooling.

I decided to run the wires through their holes in the PCB, I guess that's how it was planned before they started soldering the wires directly to the pads.
That way I managed to make the lenghts quite a bit shorter.

I ran it through my 8ohm ballast resistors, I got 33 V before some distortion appears on the scope, which means around 135 WPC, for a spec of 125WPC.

And I added an IEC mains connector.















New Bourns 500ohm trimmer





Before firing it up, monitoring the bias current....I was a bit nervous there, but all went well.

 

[Bert 1100]

A few more pics...













33VAC RMS before distortion appears = 135WPC
It actually starts clipping at 36VAC



clipping with "Soft clipping" OFF :



Soft Clipping ON : it smoothes out the waveform BUT it also starts clipping sooner.

 

[Bert 1100]

deleted (test)

 

[Goldie99]

Beautiful work - I'll look forward to seeing the finished Walnut face-plate.....

I'm not entirely convinced about the one different 2SC3519 output yet, in terms of current sharing especially. One to have a think about & get my head around.

 

[Bert 1100]

I'm not entirely convinced about the one different 2SC3519 output yet, in terms of current sharing especially. One to have a think about & get my head around.

I'd be interested to hear what you think of this

Meanwhile, the walnut faceplate is done
It looks pretty good, I'm happy.

started with a big 2 inch thick plank....



splitting in half the thickness



The grain is very nice



Then onto planing, and the fence on my planer just fell apart....so much for buying cheap machines :-(



Anyway, I did without the fence...


.



That's what I use to brush the wood, it brings out the structure



Then a coat of linseed oil....

 

[Bert 1100]

I have no photo of how the faceplate is fixed, but I used a couple of aluminum angle profile, using the same points as the original.
The original button is of course now much tto short, so this was my answer :

"Turning" a 12mm dowel down a bit on my drill press...



And a high-tech solution to attach it to the old button



And it's finished !



In my system, with the Yamaha CA-810 as preamp, sounds pretty good !

 

[Goldie99]

Beautiful piece of timber - and very good to see it oiled, not varnished. Nice job.

I think I'd have chosen Tung oil, just for the added waterproofing, but that's just my preference.

 

[Bert 1100]

just for the added waterproofing

I hope it doesn't get wet any time soon
And yes I love oiled surfaces, and varnish is such a pain, while oil is very forgiving

Tonight I swapped the Yamaha for my fully rebuilt Marantz 1060 as a preamp, the result is really really good.
Still very nicely detailed (maybe more ?) but warmer, with a bit more bass and a softer but very nice treble.

 

[NAD80]

Nice work. Looks really good. Sorry about the planer.