Technics SL-P990 Skipping- Laser adjustment?

[matski]

Hi All,

Hopefully someone out there can help me with my cd player. As mentioned, it's a Technics SL-P990. Plays for a few minutes then randomly skips either back a few seconds or forwards in large chunks. I've searched through the threads and checked that the disc clamp is secure, everything is free and mobile as necessary and I've cleaned the lens with distilled water. Still the same. Does anyone have a service manual/guide for this player or provide me with details of how to check for laser strength/focus as you can with a CDM4? It's a great player and I'd hate to bin it. I also have a SL-P777 and this gives me no trouble at all but the mechanisms are different.

Regards

Mat

[Gasho]

Laser is OK.
Try to clean lens with isopropanol and dust off spray ( compressed air).

What mechanism is inside? CDM 12.1?
A lot of old players with DC spindle motors have problem to mantain correct speed becouse motor brushes and comutator are not clean.

Motor must be opened and cleaned.

[matski]

Hi Gasho,

Thanks for your reply. Are there any identifying characteristics for cdm 12.1? I know what CDM 2 and 4 look like but not 12. I've actually just taken a drastic step and cleaned the lens with optics cleaner and it's a whole lot better, although time will tell as to it's effectiveness. If you do have any info regarding the 12.1 re adjustment it'd be greatly appreciated for future reference.

Many thanks

Mat

[Gasho]

Try google to find a picture of CDM12 .
CDM2 or 4 have swing arm radial laser move sistem , the CDM12 have straight line laser moveing from spindle center .

[matski]

Hi Gasho,

She's still playing perfectly! Ahh bless Windolene. My mechanism doesn't look like the cdm 12.1 as far as I can see. I taken a couple of pics but can't downsize them enough to post them. Could I email them to you?

Thanks

Mat

[matski]

Hi again,

It has started skipping again after around 3 hours faultless play. I think I have found the problem. The laser is moved via an elaborate electromagnet system that I have not seen before. It parallels the guide rails and moves in a push pull arrangement. I noticed when closing the drawer with no cd in that the laser was sticking on the guide rails when powered up, sometimes moving further than other times. I have cleaned the rails with contact cleaner leaving no residue and now the laser seems to move far better. This I would imagine could most certainly have given me the symptoms I had. I'll keep an eye on it and see if this has worked.

Thanks

Mat

[anatech]

Hi Mat,
That's a Technics mechanism.

You need to do the following. Release the slide rails and work on them one at a time. Watch you don't damage the carbon track that provides position information underneath.

Clean the rail with Alcohol or lacquer thinner. Use a touch of very fine "diamond oil" or some other very fine oil (single weight, no additives). Make the coating even and wipe it off lightly. Reinstall the rail and repeat for the other. You may want to clean out the bearings in the head.

The slide motor is a linear type. Very quick. I like them. If you don't have the proper oil, try to buy some from Technics. It isn't cheap, but it is critically important. This transport is far better than the Philips types.

-Chris

[tubenut]

Hi Anatech, could it look like this?
Anyone recognise this mech?
I removed this from the Acurus last night and found a little PCB including crystal and some chips on it, one of them branded Technics.
I am really trying to establish what mech this is...

Thanks

[matski]

Hi anatech,

Many thanks for the information regarding the Technics mechanism. I must admit it does seem far better quality than the cdm2 in my Cambridge CD2. You are right it is very quick and absolutely silent in operation. I will try the method you suggest with each rail and will try to obtain the correct fluid as I intend to keep the player. After opening my SL-P777 and feeling disappointed as to the lack of gubbins inside I was well pleased looking in the 990. Nice big Nichicon Muse caps,with 99% of the others being Elna, coloured red, plus twin psus! It sounds great when on form so I'll keep on trucking.

Thanks again

Mat

[anatech]

Hi Guillaume,
Sorry, I don't recognize transports all dressed up. I need to see them naked (that's how they get when they are on the bench).

I am not at all impressed with newer Philips transports at all. They have highly variable RF output levels, high noise and lot's of jitter. Plastic landfill. The "pro" designation is a bit of a joke. The old Sony mechs using the KSS-210A was miles ahead in quality, and it was repairable.

Technics makes their own proprietary mechanisms. They generally work very well and last.

-Chris