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NAD 3020 re-cap

invalidbuffa

invalidbuffa

Super Member
I just picked up my first NAD, a second-revision 3020 (with the four filter caps next to the headphone connector). The inside was very dusty and everything needed a thorough cleaning, including the controls. Here it is after some T.L.C.

PXL_20211204_232307044.jpg

All screws are present, the inside is untouched, and everything works...and oh boy does it sound nice through my Forte IIs.

I'd like to recap it using Leesonic's recommended parts, but I'm having trouble finding his spreadsheet that's referenced in other 3020 threads. Does anyone have a copy?
 
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invalidbuffa said:
I just picked up my first NAD, a second-revision 3020 (with the four filter caps next to the headphone connector). The inside was very dusty and everything needed a thorough cleaning, including the controls. Here it is after some T.L.C.

View attachment 2412508

All screws are present, the inside is untouched, and everything works...and oh boy does it sound nice through my Forte IIs.

I'd like to recap it using Leesonic's recommended parts, but I'm having trouble finding his spreadsheet that's referenced in other 3020 threads. Does anyone have a copy?
Click to expand...

Hi there - I don't have a copy, but I did have great success by recapping a 3020 with a kit I found on Ebay. I believe the seller was German - all good quality caps, Nichicon, Panasonic etc.
 
invalidbuffa said:
I just picked up my first NAD, a second-revision 3020 (with the four filter caps next to the headphone connector).
Click to expand...

I think you'll find this is actually the more desirable original version of the 3020 - it seems to have the additional transformer tap for the power LED board supply, as well as diodes D605 & D606, all of which were removed in later versions. Nice find, and looks to be in good shape.
 
Markoneswift said:
Hi there - I don't have a copy, but I did have great success by recapping a 3020 with a kit I found on Ebay. I believe the seller was German - all good quality caps, Nichicon, Panasonic etc.
Click to expand...

I saw those kits too. It doesn't seem like a bad option...

Goldie99 said:
I think you'll find this is actually the more desirable original version of the 3020 - it seems to have the additional transformer tap for the power LED board supply, as well as diodes D605 & D606, all of which were removed in later versions. Nice find, and looks to be in good shape.
Click to expand...

According to the various service manuals I've found, those diodes and the transformer tap don't appear in the earlier (earliest?) revision either...strange. My model was also assembled with matsushita (panasonic) caps. I've heard some used sanyo parts and weren't as reliable.
 
Thanks. I found all the docs I need for my unit on hifi engine.

I've been working on a capacitor list based off of the information I could gather from Lee's posts, using Nichicon KLs in the signal path and KWs everywhere else.

Power supply:
C901, 902, 915, 916
2200uf 35v : KW 3300uf 50v UKW1H332MHD
C905, 906
470uf 35v : KW 470uf 50v ‎UKW1H471MHD‎
C907, 908, 911, 914
47uf 35v : KW 47uf 50v UKW1H470MED1TD
C912, 913
4.7uf 35v : KW 4.7uf 50v ‎UKW1H4R7MDD1TD‎

Phono:
C401, 402, 417, 418
4.7uf 25v : KL 4.7uf 25v UKL1E4R7MDD1TD (or film? wima mks2?)
C409, 410
47uf 6.3v : KW 47uf 25v UKW1E470MDD

Pre:
C513, 514, 515, 516, 523, 524
47uf 6.3v : KW 47uf 25v UKW1E470MDD
C517, 518
47uf 6.3v : KL 47uf 10v UKL1A470KDDANATD

Amp:
C601, 602, 603, 604
1uf 16v Tantalum : KL 1uf 50v UKL1H010MDD1TD
C605, 606, 625, 626
47uf 6.3v : KW 47uf 25v UKW1E470MDD
C615, 616
1000uf 6.3v : KW 1000uf 10v ‎UKW1A102MPD‎

Soft clip:
C701-706
47uf 6.3v, 25v : KW 47uf 25v UKW1E470MDD

LED meter:
C801, 802
4.7uf 25v, 16v : KW 4.7uf 50v ‎UKW1H4R7MDD1TD‎
C806
1uf 16v : KW 1uf 50v UKW1H010MDD
C807
220uf 16v : KW 220uf 16v UKW1C221MED

Am I missing anything? I'll also get trim pots and .22 ohm resistors for DC offset and bias adjustment.
 
I haven't checked all your part numbers, or mouser stocks, but I can't see much wrong there, although you do seem to have missed C527 & 528 (Tants.) - MKS2 fits well.

C401, C402 - I tend to use KL. It might be possible to 'shoehorn' an MKS2 in there, but it's very tight space-wise.
C601-C604 - I tend to use MKS2, but it's just personal preference.
C605, C606 - if you use the LAB input at all, it may be worth going to KL.

I'd also suggest to regrease the heatsink mounted parts, for peace of mind if nothing else. Beyond that - enjoy it, they're nice amps, well worth the effort.
 
The main caps I would recommend going to something low impedance/high ripple like Nichicon PWs. Likewise the regulated power supply caps, the larger ones you can go up to 680uF.

You don't need 0.22 ohm resistors to set the bias. I always use a 1 ohm resistor and set the bias to 30mV as per the later service manuals, remembering to short the 1 ohm resistor after using it for testing.
 
Goldie99 said:
I haven't checked all your part numbers, or mouser stocks, but I can't see much wrong there, although you do seem to have missed C527 & 528 (Tants.) - MKS2 fits well.

C401, C402 - I tend to use KL. It might be possible to 'shoehorn' an MKS2 in there, but it's very tight space-wise.
C601-C604 - I tend to use MKS2, but it's just personal preference.
C605, C606 - if you use the LAB input at all, it may be worth going to KL.

I'd also suggest to regrease the heatsink mounted parts, for peace of mind if nothing else. Beyond that - enjoy it, they're nice amps, well worth the effort.
Click to expand...

Good catch, thanks. Does thermal compound degrade over time?

leesonic said:
The main caps I would recommend going to something low impedance/high ripple like Nichicon PWs. Likewise the regulated power supply caps, the larger ones you can go up to 680uF.

You don't need 0.22 ohm resistors to set the bias. I always use a 1 ohm resistor and set the bias to 30mV as per the later service manuals, remembering to short the 1 ohm resistor after using it for testing.
Click to expand...

Thanks for hopping in, Lee. I'll have to wait for the 3300uf PWs to come back in stock...digikey shows an estimated ship date of 12/14, fortunately. I assume a 1k trimmer in the RX1 and RX2 positions will work fine, as those are both 150 ohms in my unit. What are the brown film caps you used in the phono stage?
 
invalidbuffa said:
Good catch, thanks. Does thermal compound degrade over time?



Thanks for hopping in, Lee. I'll have to wait for the 3300uf PWs to come back in stock...digikey shows an estimated ship date of 12/14, fortunately. I assume a 1k trimmer in the RX1 and RX2 positions will work fine, as those are both 150 ohms in my unit. What are the brown film caps you used in the phono stage?
Click to expand...

Thermal compound very much so. You can either remove, clean, and regrease the mica washers. Or get new thermal pads.

I've never seen 3300uF PWs in stock. Do a search for 3300uF 50V caps with 7.5mm lead spacing, and sort on the ripple current (you want the highest). There are some United Chemi-Con ones on there right now. To be honest, with the supply situation what it is now, you have to get what you can get.

As for RX1 and RX2. Use a 1k2 resistor for the one that's in parallel with the 1k trimmers, and set these to 500 ohms approx, then dial in the bias.
 
I just recapped a 3020 with Nichicon caps. Increased the 4 power caps from 2200uF to 4700uF. The distortion test was interesting. It starts to rise right above 20W per channel with the soft-clipping switch turned on and hits 1% THD at 30W. With the soft-clipping turned off, it hits 1% THD at 40 watts. Also tests better with it off below 20W. Here are the stats

Both channels driven at 20W, 8 ohm

freq. L %THD R
20hz .0020 .0030
1khz .0032 .0034
5khz .0053 .0053
10khz .0044 .0047
20khz .0018 .0024
%IMD .0020 .0022

Testing through the 'LAB' input, which bypasses preamp and tone control, it puts out around .0015% THD at 1khz
 
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