Naim CDM9 Pro turntable motor fixit (sort of)

[MJS]

As many of you know the later Naim CDI and CD2 players used the Philips CDM9 pro transport unlike the practically bullet-proof CD4 used in earlier the CDI and CDS or CDM9/44 in the CD3. These are rarer than rare now and only the lasers can be swapped out if you can find one, which cures 99% of the problems we've seen with them.

For the 1% with a faulty turntable motor there hasn't been much you can do. So I compared the Naim circuitry with the Philips players of the same vintage which used the CDM9 plain transport. As it turns out, Naim's motor TTM drive circuit is almost textbook and the extra circuitry on the servo board drives the hall motor on the CDM9 pro. It turns out all you need is a simple push-pull emitter follower pair on the TTM drive from the main CDI board then connect the output of that to the turntable motor of a plain CDM9 (red to ground, black to emitter output). You can now use plain CDM9 transports in place of the Pro.

 

[Darren]

This is interesting.
As an aside: I've always hankered after an original CDS as part of my retro collection. Is there any part of this unit which is unobtainium now? Can you service faulty units in all circumstances?

 

[MJS]

The CDS is serviceable as long as we can find Philips/Marantz players of the same vintage - the CDM4 lasers are very solid and last for years. DACs are proving hard to find but a donor player often yields the right parts. New parts are unbelievably expensive or of unknown provenance. We still haven't found one we cannot fix.

 

[Dowser]

As many of you know the later Naim CDI and CD2 players used the Philips CDM9 pro transport unlike the practically bullet-proof CD4 used in earlier the CDI and CDS or CDM9/44 in the CD3. These are rarer than rare now and only the lasers can be swapped out if you can find one, which cures 99% of the problems we've seen with them.

For the 1% with a faulty turntable motor there hasn't been much you can do. So I compared the Naim circuitry with the Philips players of the same vintage which used the CDM9 plain transport. As it turns out, Naim's motor TTM drive circuit is almost textbook and the extra circuitry on the servo board drives the hall motor on the CDM9 pro. It turns out all you need is a simple push-pull emitter follower pair on the TTM drive from the main CDI board then connect the output of that to the turntable motor of a plain CDM9 (red to ground, black to emitter output). You can now use plain CDM9 transports in place of the Pro.

Nice - but how many cdm9 pro motors have actually failed? My original CDI came with a CD platter thoroughly abused trying to Prise it off, I guess because someone thought the motor was faulty when the CD failed to spin at TOC - motor was fine, I just need a new platter. The damn things are near indestructible, no?

 

[wylton]

We still haven't found one we cannot fix.

That's good news, hoping to hang on to mine for a long time yet.

 

[MJS]

Nice - but how many cdm9 pro motors have actually failed? My original CDI came with a CD platter thoroughly abused trying to Prise it off, I guess because someone thought the motor was faulty when the CD failed to spin at TOC - motor was fine, I just need a new platter. The damn things are near indestructible, no?

Yes, this is the first one I've seen fail in 25-odd years, I think it's a bearing issue. But you're right, they are fairly indestructible. The CDM9 plastic platter has issues of its own, but any CDM/VAM platter will fit the DC motor spindle and the Clamp5 works on pretty much every player.

 

[Miles Essery]

In my Sugden AU51 the ribbon to the motor is torn. I found a reference to the Matsushita CDS8-6 motor which of course is no longer available. Fitting a CDM 9 motor would be a better idea. I am not sure if there is a TTM drive on the main
board. Getting any schematics from Sugden has proved difficult. Not like the old days when everything was supplied in the manual.

 

[sq225917]

The ribbons are all standard items available from farnel. Take a pic.

 

[Dowser]

Or use litz wire to replace or repair it

 

[Miles Essery]

I had had a look in my Farnell catalogue 2018 and online (all 25 pages) for a replacement ribbon. They do not appear to have replacement flexi pcb ribbons. I had thought of scraping away the coating and soldering stranded wire across and then epoxy coating. The existing surface coating appears to be some sort of epoxy and is extremely hard to remove, even with a scalpel. Using litz would be interesting, but the a problem with is, that the break is at the point where it broken ribbon flexes.