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Naim self service NAC202 and NAP200

K

kiran1103

Member
As suggested by fellow pfm member, posting this in diy forum. I tried looking for information on threads here and acoustica.co.uk and have got few pieces but would like to know if anyone did a full refresh of these and what caps were used. BHC is now renamed to Kemet so checking for the like ones. If anyone has the list of what all were replaced would like to follow. They both are more than 10-15yrs I guess and I have a intermittent pop from the speakers. I think its because of capacitors and havent had the chance to open it up yet. Apart from the 10000uf 50v and 4700uf 50v I dont know the other values and which make to use. Will take one after other.

NAP200

For NAP200 apart from the 10000uf and 4700uf there are Four (4) 220uf 16v SG ones. For this spot I am thinking Elna Simlic II. Any benefit using Nichicon KZ? I read both are fine but not sure which one retains Naim sound or betters. Thoughts? In addition there are 6 yellow tants and 4 blue tants. Anyone knows the values and which replacements. clone kit says 10uf/25v and 47uf/16v (2) for yellow ones per channel. If thats true is Kemet T356 correct replacement?
 
To find out the Tant values and make, why not simply take the top off and have a look? A bit of detective work will then tell you the make from the markings. If you want to retain the Naim sound you need to replace all the caps with like for like. From my experience, changing the make and type alters the sound away from the Naim house sound (especially the feedback capacitors) but only your ears can decide if you like what you hear.
From what I have seen (others may enlighten you further) Naim mostly use cheap and nasty Samwha SG Electrolytics for decoupling (as you have found) and the odd ELNA, though they seem to use various makes of good quality Tants for signal coupling. I suppose it depends on what they can get at the time. Also, don't rely on a clone kit for values of anything as I have heard too many stories of the suppliers substituting components for what they have in stock at the time!
 
Unless (like me!) you followed Naim's ridiculous advice to leave it on all the time (maybe to get around their underrated push button power switches) you very likely don't need a re-cap. Did you know Naim traces like to lift up? Now you do. Maybe they improved the PCBs after the Olive series but your kit is recent enough to still leave well enough alone for another decade. According to the datasheet from the people that make them tantalums don't have a wear out rate, you can consider them like film caps and resistors. Maybe Naim had a bad experience with tants in the 1970s but they are more reliable now? I recapped my late Olive 250 but left the tants, I prefer listening to datasheets than the Internet. However, tants like to fail short so maybe I'm making the wrong decision and you shouldn't listen to me. If you do a total recap including tants you need to check the offset and bias before connecting speakers. In fact you'd be very foolish to not first power up with a dim bulb limiter, which you should Google.

If you're a sophomore like for like is the only way to go with just about everything, I learned that the hard way, I wrecked a lot of stuff, if you want to learn by modding buy something old and cheap like a NAD and learn on that. I don't know what to make of Samwha, I think they are S.Korean, they actually are one of the few companies that make low leakage audio e-caps (but that you can't buy anywhere) I believe Elna stopped a while back and Nichicon just ended the KL series. I wouldn't just write Samwha off, I bet most first tier cap companies like Nichicon, Vishay, CDE, Panasonic etc, are probably making them in Taiwan or Mainland these days.

If your amp is making an intermittent sound I really doubt it's an electrolytic, probably a transistor before the outputs. If the 200 is regulated it could be an e-cap but it will cause a slight distortion or rush, or constant crackle, not go intermittent. First fix that and ask the tech if he thinks it needs a recap. Not sure what the rails are on the 200 but if you go ahead and change the filters if they fit I would replace 50V caps with 63V, that's the only improvement you will make over factory.
 
Thank you Bad Parameter. Its really helpful. I completed NAP200 with power caps plus 4 samwha 220uf 16v. Replaced it with Kemet 10000uf 63v, 4700uf 63v and Elna Silmic II black and gold ones of 220uf 16v. I did not change tants and measuring circuit was not ideal so didnt touch it. The Kemets were 40mm height so it was a very tight fit of the case. I dont know if I should be anal about the compressed caps with the case. When I find the correct height part will try to replace. I then checked with DBT and that passed. Then put that on variac with 25AC then every 15 mins bumped until I reach 120v which is close to line voltage here. I then checked the bias across 022 resistor for each. It was at 3.2mv. Per guidance I bumped it to 4.2mv each so across its 8.4mv. Packed and connected it. The old caps were close to value and ESR was just 0.02 from the peak capacitor meter. The new caps had date code of 2022. But they were measuring on the lower end of 20%. i.e., 10000uv was showing 9230uf. Maybe they needed reforming so hence used variac to get them reformed. However I did not retest the capacitor value. The amp now has greater details and wider soundstage. Bass has tighten up as well. I am not sure if it was because of the caps or the bump in the bias. DC offset was within spec as well. I read that Elna silmics II have 100hour burn in but right away I feel its amazing. I dont plan for tants right now. I read that they just get mellow with age and if fails the amp just stops working. So maybe will keep it for some other time.

I was hoping that the pop from speakers occasionally rectified by this but it did not. I still hear it and I notice its from left speaker only. The full set up is nDAC to NAC202. NAC202 is connected to HiCAP2. The pop I think it emerged after the upgraded the HiCap2 with new Kemet caps and Avondale ASR2 module. It bought significant change but since the pop emerged after this I may write to Les/Gavin to see if this was encountered elsewhere.

Will move on to NAC202. I got all the elec caps of Elna Simlic IIs. Since its close to 50-60 caps will take it slowly when I find a long weekend. Thank you
 
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