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NAD 2200PE upgrading

Hi @bill114 ,
Here you go...I found this by digging deep into the internets ;)
Good luck!
Oh, and if you follow the NAD service manual schematics, you should see the voltages at different test points...aside from the voltages listed on the IC schematic ( and the NAD schem), the rest of the pins should read 0V.
 

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Resurrecting the thread... thanks to GREAT info provided by Pilot and pwauk12 I'm in the middle of re-capping the first of my pair of 2200s. Relays and input board are done successfully and now into the power supply. For anyone that doesn't want to mess with the dummy pins on the United Chemicon 100v caps Newark has these Kemets: https://www.newark.com/kemet/alc70a103eh100/aluminium-electrolytic-capacitor/dp/85AC3988 The snap-in pins JUST fit into the wide pads on the PCB!

I'm currently in the process of specing the 3xx series caps for the amp boards. The online 2200 manual BOM stops at c330 but I've found film and ceramic caps numbered to c342. Plus for the life of me I cannot find c325-c328. Can anyone (Pilot or pwauk12) advise on this discrepancy?
 
Gil- there is a separate 2200 PE service manual available on HiFi engine or Vinyl engine.- This shows all the caps in the circuit diagram, but does not list them in the parts list.

also you might consider looking at the 2600 and 2700 service manuals- as they are the same for the C series (look for MAR and MAL 593 on the board- there will be a letter (A/B or C) which tells you which is which- if there is not letter then it is an orignal 200.
also I wrote some more technical detail here-

https://quirkaudio.com/?page_id=707#

and thanks for the heads up on the Kemets
 
I've been on your website but for some reason didn't find the link above, just the general 2200 info page and your list of mods you also shared on AK. VERY helpful info going forward!

Yep, it's the 2200 PE manual from HiFi that I'm referencing. Both of my 2200s are PEs with "C" amp boards so that would explain the caps from 331 on up. I have the 2600 PE manual downloaded, the circuit diagrams are certainly easier to read! I'm putting together a project list for the 3xx series caps at the moment but while the 2600 manual lists the added caps it doesn't give values like the 2200 manual did, just type and part number. Do you happen to know the respective values for them? I guess it's possible to read the codes on the actual caps but ceramic and films are so hard to read when installed and I'm burning-in the input and power supply mods right now.

Another tip, I noticed in your pics that you don't appear to upgrade the L & R output leads from the input board to the main amps. Would lower impedance wire help or hurt there? The R channel lead wire on mine was so hardened that it broke while I was desoldering nearby caps and the OP amp. After attempting to repair that THIN wire I gave up and looked around for a solution. Being an IT tech for over 30 years I have alot of dead PC power supplies laying around. The pin sockets crimped onto the wires for the 4-pin floppy power connector are compatible with the 2-pin housing of the output leads. A little bit of pressure from a precision flat blade screwdriver and they can be removed from the PC connector. The wire gauge is a little larger so I had to drill out the through holes on the input board to match but otherwise saved me from having to source new sockets and stripping/crimping onto bare wires.
 
hi Gil
scroll down on the link- there is a "tech section" that m ay be of interest.

yes it is a ad tricky- the 2600 service manual has a parts list- feel free to ID the parts you are uncertain about and I will try and assist

and your wire plan sounds great- to date I have not had any issues. If you have C series boards let me make the following suggestions:

C203/204- 10uf BP Nichicon MUSE (UES)
C215..218 470uf 50v Nchicon HE
C310..304 100uf 100v Nichicon HE
These correlate with the 2700 series NAD boards

and
C225/226- WIMA 68pf 50v 5%
C211/212 WIMA 390pf 50v 5%
C205/206 WIMA 470pf 50v 5%

hope this helps
 
oh one more thing- you might try a 47uf BP MUSE for c203/204- this is the value used in the 2700
 
Thanks for helping to fill in the blanks!! Much to digest before I finalize that parts list. My rebuild of the input board and power supply caps worked, can't say it sounds any better but I suspect more benefit will come from doing the amp boards.

One last question for a bit, do you replace the DC balance\bias adjustment pots or simply hit them with DeOxyIT? I found a good primer on the importance of doing the trimming, especially after significant changes to the components: https://www.tnt-audio.com/clinica/bias_e.html Obviously you know this but the link might benefit others. The "stock" units on the 2200 are open 1 turn devices, do you see any benefit in using multi turn pots?
 
Hi
replace the pots- the bias pots particularly- bourns single turn are fine.

what IC did you put on the input board?
 
OK, will do with the pots. It turns out there's not much choice in the 10mm format but single turns are available, even found 1K Ohm at 10% tolerance.

I installed DIP sockets to facilitate trying different OP amps. I bought a pair of both LME49720NA and OPA2134 to experience the difference. It appears other 8 pin amps are compatible too so don't know what I'll do after listening to the first two.
 
Today I had time to finish the upgrade of the 2xx caps (thanks mandatory "stay home" order!!) and am burning things in at the moment. So with the input board (still stock OP amp) power supply, and most of the amp board caps done it sounds quite a bit better than what I had before! DEFINITELY need to replace those pots though, difficult to get them just right. I kept the meter on the bias taps (no music playing, just idle) for a few minutes after adjusting, they creep up incrementally for awhile. Is that normal or because of the old pots?
 
yes the amp needs to stabilize at temperature- so let it warm up for about 15 minutes and then adjust. It is also good practice to check the bias voltage (plus and minus 1.77v- marked on the circuit) to make sure this is OK.

and stay at home! (and stay well...:)

Fortunately mouser and digikey are both delivering
 
pwauk12 said:
yes the amp needs to stabilize at temperature- so let it warm up for about 15 minutes and then adjust. It is also good practice to check the bias voltage (plus and minus 1.77v- marked on the circuit) to make sure this is OK.
Click to expand...

I did give it a good half hour warmup before making the trim adjustments. Which is why I'm curious about the creep after getting it to spec. Best to not worry about it until I install the new pots.

pwauk12 said:
Fortunately mouser and digikey are both delivering
Click to expand...

Yeah, and so do eBay vendors. Been spending too much time there recently, last night I bought a 2600 for $215 delivered. Seller reports left channel as "muffled" at times. Most likely relays, done those twice already!

I'm curious about your input board mod for c111-114. There's a pic of the front on your site with the 47uF 'lytics and I can see the ceramics on the backside in another. Are you able to push both leads through the PCB holes and solder that way or soldering one side normally then tacking the ceramics on the back after that?
 
Gil Bucher said:
I did give it a good half hour warmup before making the trim adjustments. Which is why I'm curious about the creep after getting it to spec. Best to not worry about it until I install the new pots.



Yeah, and so do eBay vendors. Been spending too much time there recently, last night I bought a 2600 for $215 delivered. Seller reports left channel as "muffled" at times. Most likely relays, done those twice already!

I'm curious about your input board mod for c111-114. There's a pic of the front on your site with the 47uF 'lytics and I can see the ceramics on the backside in another. Are you able to push both leads through the PCB holes and solder that way or soldering one side normally then tacking the ceramics on the back after that?
Click to expand...

lets not try and outbid each other on EB..:)
 
pwauk12 said:
hi gil= yes exactly as you describe
Click to expand...
You mean the first description, leads inserted front and back then soldered??
pwauk12 said:
lets not try and outbid each other on EB..:)
Click to expand...
Hey, it wasn't an auction just a "buy now" listing. Had been watching for a few days at $180 (+$30 shipping) then last nite he dropped the price to $150 which was all I needed. This should be the last major thing I get near term so need to worry about me in an auction. ;) If it turns out to be a simple new relay and recap then I'm selling off one of the restored 2200s. Don't think I'd ever need to bridge, my Forte IIIs are loud enough with just one amp! The front panel level knobs are what I wanted, I feed the amps directly with a good quality desktop DAC controlled by a PC via Toslink.
 
I have attached a photo- the 47uf are connected on the component side and then bent at 90% so they hang down from the board towards the bottom of the NAD. The ceramics are then piggy backed.

Good score on the 2600- do a similar set of upgrades and you will have a great amp
 

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