NAD 1020 preamp mods anyone?

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Anyone modded one of these? I noticed there are a few polarized electrolytic caps in the signal path, I wondered if they can be changed for non polarized film caps? I would also eventually like to swap some of the carbon resistors for metal film.

I know this is an old preamp but Im curious to know someone else's experience with it.
 
I was working on replacing all polar caps on my 1020A. And along the line amp part, I inadvertently misplaced the polarities of 2 little caps, and the amp didn't make a sound afterwards. It took me two months (!!!!! Yikes ) to sorta "see" the problem and re-soldered the polarities right.

So these electrolytic polar caps do matter.

To add my experience to modding the 1020A, if the PSU caps are to be upgraded, you may not hear or see any major or noticeable improvement until fast recovery bridge rectifiers or diodes are swapped in. Then, with the PSU upgrade, the background noise, esp intermittent high pitch bursting noise, will improve. Probably an aging issue, but is cheap enough to be included in a rebuild project.

Other mods included:

1. volume potentiometre (tried a counterfeit ALPS 19-step 200k, and another 50k carbon one. Both improved stereo tracking a lot from the crappy original ones . SO I think expensive pots may not contribution to more improvement upon those new pots, even fake ALPS are good enough here.), along with loudness wires bypassed/eliminated, or permanently tapped to the volume pot (most pots don't have a fourth pair of legs for the loudness control). I did the latter.

2. good de-oxit clean on all mechanical-electrical contracts

3. re-glued all square buttons on facia with hot glue or two-part epoxy glue

4. re-soldered with good flux (re-melt) all solder joints esp those on PSU, input/out RCA jacks, and grounding planes/points. This alone cured one of my 3020 from no sound to beautifully working instantly.

5. upgrade PSU with fast diodes/rect. bridges, and new low-ESR caps.

6. either eliminate the whole independent headphone board, or re-cap it. I took the latter approach.

Note: Some time ago, while I was placing orders on caps for my project on my 5 Nikko 220 (2 of them)/230/440/Alpha 2 power amps, I decided to order multiple quantities electrolytics of small values (each 100 pcs of 0.47uf, 1uf, 3.3uf 4.7uf, 6.8uf, 10uf, 22uf, 33uf, 47uf, 68uf, 100uf, 220uf, 470uf, 330uf@25v/50v/100v). From taobao, they cost me about US$170 shipped in several lots.

After Mine has been given 60 hrs run-in, and it now starts to sound as sweet as my Nikko Beta 1.

Terence
 
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