Troubleshooting NAD 510 CD Player

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Where was the laser sourced from?

CDM12's of all varieties have long been out of production and there are many reports of substandard and cheap copies being supplied.

Its always worth making sure the disc runs true and with no runout. Viewed horizontally when spinning and it should be absolutely true with no run out at the disc edge. A scope will show runout as a bouncing of the RF signal as the focus coil continually compensates and moves the lens up and down with each rotation.
 
I bought it over ebay of course, from a German seller :)

Of course it's some Chinese cheapo. Better than nothing anyway. The original one actually also was not exactly top-notch:)
It was only the laser unit that got replaced, the rest of the drive, including the spindle motor, is still the from the original Philips unit.
You can clearly see the focus mechanism working to maintain focus when playing the outer tracks, but this is true for all drives. Maybe the problem lies in cheaply made optical parts. Or tracking is not always as fast it it is supposed to be.

Also, whether the clamper is sitting exactly centered after inserting the CD is a matter of hit or miss in this player. Guess this is normal with this drive? However, the CD itself always seems to be properly centered. As always the same CDs cause problems, it seems to me as if this particular laser unit is having a problem with slightly warped disks.

I *think* I can rule out the electronics.
 
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Ideally the lens should be absolutely (visibly anyway) stationery when playing an end track. If you can see it moving much then the runout is excessive. Unfortunately that's another problem with non original parts, the platters seem less than perfectly moulded.

Ideally you could do with looking at the RF signal to try and gauge what is happening.

Donberg might be worth a look for pickups. I've never used them personally but the name crops up a lot. They list several if you do a search for CDM12.1

Audio Spare CDM12.1/15 (CDM 12.1/15) - LASER MECHANISM UNIT MARANTZ CD63II... - UK (GBP)
 
I found CDs where the lens is only making minimal moves. Others make the mechanism move wildly, some almost in some circular shape, which in addition indicates bad centering. One is warped so badly that the lens has to move up and down several times during each turn, which looks crazy, like driving over rocks.
Interestingly, this is not really the point. This CDs plays flawlessly.
Another one, which is far nearer to being perfectly even, causes short dropouts.
As I mentioned, the platter and motor are original, and therefore probably as good as they can get.

I may try a different laser some time.
First, the player has to make the sound I want to hear. No idea if I will ever get to this point. :)

This evening I turned on the NAD and listened to a few CDs.
For itself alone, it sounds quite ok. But still, listening to my old Arcam, which is currently my only reference, feels like coming home.
 
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Interesting. Sometimes CD's can vary a lot in reflectivity, typically one in a bunch will give a significantly lower RF level than all the others. Occasionally these discs can look discoloured with a yellow tinge.

So the money is on the replacement laser not being up to standard... but if you are not really liking the player sonically then its maybe not worth spending on and investing time in.

Decision time :)
 
Hi Mooly,
again, thanks for your input!

I must say that things have improved since fiddling with the laser power pot, although I am know that this is not recommended normally. But there wa not much left to lose here.
The player always was meant as an object of experimentation. The good thing is that, unlike in other NADs, the DAC Board is separated and changing components is a matter of a few minutes.

Also sonically, it has gotten better for my taste.
Some ideas are still left. I maybe will put in a separate transformer for the DAC board, maybe also together with a better regulation. This will not cost a fortune and there is plenty of space in the player. Also the supply for the transport has quite room for improvement.
 
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