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NAIM CD3 Mods and servicing...& the anatomy of the mother board.

stackowax said:
What you are talking about--"hums through the case"--sounds like transformer hum caused by grunge on the mains. If that's what it is, not much to be done about it.
Click to expand...

Thanks, but the amp doesn't hum at all. Though it used to sometimes in the afternoons when the mains were particularly dirty for some reason. Would the CD3 hum if the amp doesn't?

yairf.

Thanks, if that was intended for me. I don't really understand but I probably know a man who does.
 
hughjampton said:
Thanks, but the amp doesn't hum at all. Though it used to sometimes in the afternoons when the mains were particularly dirty for some reason. Would the CD3 hum if the amp doesn't?
Click to expand...

Seems possible. I'm no expert but if the transformer is made by someone else or is of different specifications then it might well hum in the amp's transformer doesn't.
 
OK, so the job is now complete and the CD seems to be playing beautifully, but thought it might be worth reporting my findings.

The player actually belongs to another PFM'er who sent it to me for attention as:
  • It was dead in one channel
  • Skips incessantly
  • and just doesn't sound right.

When I first got it it was definitely not right - and reported an "err" on about 50% of the discs I tried (most of my discs have been ripped once and then stored - so are in perfect condition). On others it definitely skipped with some frequency.

First time opening up a CD player so I was a little nervous to say the least - and quite surprised to find out how simple it was inside. The dead channel turned out to be nothing more than lose connection at the DIN - easily solved and pretty quickly it was firing on both cylinders again.

So then I tried a few mods:
  • Removed the rectifier and replaced with a set of 4 MUR415s for rectification.
  • Replaced the reservoir caps with 12,000uF CDEs
  • Replaced the final pair of opapms with OPA627APs
  • Removed the output coupling caps and
  • replaced the LM317/337 regulators for the analogue stages with a pair of TeddyRegs set to 18v
  • and rotated the rubber thingies in the puck so they stand proud...which was actually done first before any other mod - and failed to correct the skipping or disc errors.
Straight away it fired up and began playing - only now it plays all my discs - even the ones it rejected outright before. And I thought I heard it skip once or twice on one disc - but certainly not with any regularity.

So to my knowledge I have not done anything to directly improve the skipping and/or disc read errors - yet they are gone or at least greatly reduced. I can only think of two things that I have done that might possibly have contributed to this outcome:
  1. Perhaps tired caps and lowered voltages contribute to disc read errors or more likely;
  2. the ribbon connectors contacts were dirty and bad and the mere act of breaking and remaking them cleaned them up and restored normal function.

So if your CD3 (or other Naim player) is acting up maybe it's worth a try before you send it off for expensive repairs that may not be necessary.

For this one though I went back in an did the NOS mod :) and it has me smiling right now. But I guess it's time to return it to its owner - I hope he likes it too...do I really have to send it back?
 
Hi everyone!

Hope I am not double posting, my first attempt seems to have gotten lost the moment I submitted it. (I know I am monitored, hence delayed).

I would like to do some simple mods and servicing on my CD3, building on its underlying Naim strengths, which have given me years of musical enjoyment.

Let's start with basics. In all the pictures of the CD3 there seems to be an additional grounding wire (the yellow/green striped kind) conncted from the audio output plug to the back of the case. Mine doesn't have that.

My unit was originally a 115V unit, and was converted to 230V operation by the official Naim servicing agent in Germany about 5 years ago, when I moved back to Austria. That would speak for the wire beeing considered unnecessary by them, but then again, you never know. What do you think, should I have it?

Related puzzle: The transformer is clearly still the original 115V transformer. What did they do to make it work on 230V? The big can caps are Aerovox 10000µ, if that helps. I cannot remember if they changed them, if not it might be time to do that, no?

Thank you for your suggestions.
 
don't know about the grounding wire, but the transformer has dual primaries and it's a simple shift of position of two wires to convert from 115 to 230v..accompanied by a change of fuse rating.
 
Hi LeopoldN
The Transformer is 115 /230V, just a question of how do you wire it.
The Yellow wire is the ground wire from star-ground to chassis, which is standard in early Naim CD players. Later models ran a 10R resistor instead.
There are lots of mods you can do.
First I'd separate the analog supply from the digital one - build an external PSU for the analog stage - requires additional connectors, then replace the I/V op-amp with something fancy like OP-627, add gyrators per each op-amp, and replace the DAC regulators with ALWSRs or STRs.
For the next stage you may want to look at NOS conversion and a fancy clock.
Cheers,
Yair
 
First I'd separate the analog supply from the digital one - build an external PSU for the analog stage - requires additional connectors,
Click to expand...

Can you power the analogue stage with a Hicap type PSU in the same way? How easy is it? I can't really find any information about how it's done.
 
There's a symmetric pair fo LM317/337 regs on the left near the analogue circuits. Simply either feed those from a second supply or better yet replace them with your choice of better regs....
 
hughjampton said:
Can you power the analogue stage with a Hicap type PSU in the same way? How easy is it? I can't really find any information about how it's done.
Click to expand...


Hi
Few comments:
1. The Hi-Cap produces +24V,0. It is ok to feed the op-amps with this voltage but best results are derived from +/-17V supply (max limit for OP-627). So a Hi-Cap won't fit here.
2. The on-board regs as Neil mentioned feed the analog stage so you may just replace these with more fancy stuff, but there is still benefit in separating the power feed from an external PSU rather than the internal one (which is contaminated by digital noise).
3. IIRC (but I'm not sure) the internal regs that originally feed the analog stage also feed the output relay which is a big no-no.

Cheers,
Yair
 
Hi Neil and Yair,

thanks for your comments to my post! So we got the transformer sorted out.
The yellow wire must have been updated to a resistor when they rewired the transformer.

Your suggestions for mods are surely worthy, I am fully aware of the importance of clean supplies. Once I am more experienced and have gained a better understanding of how circuits work I may attempt them.

For now I was hoping for simpler drop-in or leave-out mods, as they will be closer to my level of understanding and expertise, not to forget the monetary aspects. I am thinking along the lines of Martin Clarkes ideas for amps and pre-amps on his Acoustica pages.

Any ideas, suggestions are welcome. Maybe even Martin Clark himself would chime in?

Some things I have been thinking about are:

1) New Electrolytics. Leave value the same or increase capacitance? Parallel with film cap? If yes, which value? Which brands/types for both?
2) Output cap. Get rid of? Change? Leave alone?
3)Op-amps. 'Snip-it' mod, as suggested by Lampizator. One takes the output from the first opamp and routes it directly to the output plug via a 2.2µ cap. Good idea? Who tried it? Which caps seem to work well?
4) Changing the small electrolytics near the voltage regulators. Do? Don#t bother? With what? Lampizator suggests OsCons, but he must not have looked at the original values as those can’t be obtained in OsCons.

I feel comfortable doing the NOS conversion, it is described very well on the Lampizator website. I definitely would want to do it last though, after having explored all other routes of worthwhile improvements.
 
The NOS mod gives you much benefits sound-wise, just keep in mind that you lose the top-end.
Yair
 
yairf said:
Hi
Few comments:
1. The Hi-Cap produces +24V,0. It is ok to feed the op-amps with this voltage but best results are derived from +/-17V supply (max limit for OP-627). So a Hi-Cap won't fit here.
2. The on-board regs as Neil mentioned feed the analog stage so you may just replace these with more fancy stuff, but there is still benefit in separating the power feed from an external PSU rather than the internal one (which is contaminated by digital noise).
3. IIRC (but I'm not sure) the internal regs that originally feed the analog stage also feed the output relay which is a big no-no.

Cheers,
Yair
Click to expand...

Thanks for that. That's probably what LesW meant when he said it wasn't practical to mod a CD3 to accept a standard PSU. Mine has some Avondale mods but I was hoping to get more benefit without going the full ACD3 route.
 
yairf said:
3. IIRC (but I'm not sure) the internal regs that originally feed the analog stage also feed the output relay which is a big no-no.

Cheers,
Yair
Click to expand...

Yes, one of them them does. Is the output relay necessary? Presumably it could be disconnected and bypassed without causing problems. The new regs would then only supply the audio stages.
 
I did an external PSU to power the analog stage, I had to cut the traces so the relay still operates from the internal regs.
You can do away with the relay if you do not mind the clicks and pops during power-up and when the laser is activated or deactivated.
Cheers,
Yair
 
Ages ago now I bought a non-functional CD3, and made it work just by freeing the drive motor according to Les W's tip. It sounded quite dull in comparison to my CDS2 and I wanted to work on it but for various reasons it got put away for many months. At last I have started on the mods, two so far:

1 Disconnected the LM317/337 regulators which supplied the analogue output stages. The 337 + associated caps and resistors I removed completely but left the 317 to power the relay, cutting the track to the analogue parts. These have been replaced by TeddyRegs (originals not super teddys) working at 17V and powered by an external + and - 40V supply.

Result: much more "prat" and good to listen to. But there was still some muddiness in the musical textures.

2 Replaced the clock with a Tent Labs XO mounted on a Flea, powered by a small separate +30V supply fitted inside the CDP, following the instructions in the pfm project.

Result: a much clearer and musical sound, and now it is difficult to tell it apart from the CDS2!

There are other mods I want to carry out, such as replacing the PSU caps, remove the output tants and upgrade the op-amps, possibly even with pricey 627s for the last stage. But could someone, maybe Martin, just explain this? It sounds easy enough...

martin clark said:
Yairf - the clock in the CD2/CD3 is hung off the 7220 (but exactly like your diagram), and drives the 7310 from pin 9 of the 7220 (XO sys output).

Feed the 7220 with a new clock, and also run a second line to the 7310 pin 19 input, and lift pin 9 of the 7220 and you are much of the way there for little effort :)
Click to expand...

Does this mean make a connection from the clock output (there is a second output on the Flea) directly to pin 19 of the 7310, and disconnect the 7310 from the 7220 by pulling out pin 9 of the 7220 from the motherboard?

Perhaps I am being very obtuse but I don't want to risk doing anything wrong and irreversible.

Edit: no need for anyone to reply to the above query, as i have just tried it - and it works!

Now to sort out the main power supply.
 
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