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Old 16th October 2013, 04:44 AM   #19831
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Quote:
Originally Posted by grofus View Post
Attachment 377007 This is the clamp off an original Phillips laser mech.

Attachment 377008 This is off a Chinese copy.

The small collar next to the original goes onto the spindle first, stopping it going on too far. It fits upside down to way shown. Fat part uppermost. Chinese laser doesn't have one.
I had trouble with discs not reading and wobbling so much that you could hear them scraping.
The magnet in the original is also much stronger.
Swapping them over made a big difference.
It is not only the magnet that differs, the taper angle of the top part of the cone is also different making the new one not fit onto the top rotating disc. If you try the service mod and make the cone rotate forward and backward you will find the new one slips when rotating !!
I normally remove the old cone and put it onto the new VAM. This will grip the rotating disc firmly without slipping.
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Old 16th October 2013, 06:28 AM   #19832
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The "magnetic polarity" of the grey vs black platters is different (opposite and repels the clamp) on many mechs, certainly the CDM12 series.
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Old 16th October 2013, 08:50 AM   #19833
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Originally Posted by higlander View Post
Glad to see you now have the confidence to take apart the whole laser unit. Actually it is not difficult as long as you do it step by step and just be a bit gentle you will be alright then. Well done !!

I would suggest you also try the service mode by pressing the STOP button and the NEXT button together. Switch to different Modes to move out and move in the laser head. This will run in the gears and the slides.
Yes, I figured out service mode from the manual scan I found on hifiengine.com. It's good for checking everything works but it doesn't seem to guarantee the mechanism will work flawlessly.

I left the player shuffling overnight and it seems to be slightly better this morning. I'll apply some grease when it arrives and see if that is the missing element. I seem to have ironed out the issues with the parts in the new unit that didn't seem quite right.

Quote:
Originally Posted by grofus View Post
Attachment 377007 This is the clamp off an original Phillips laser mech.

Attachment 377008 This is off a Chinese copy.

The small collar next to the original goes onto the spindle first, stopping it going on too far. It fits upside down to way shown. Fat part uppermost. Chinese laser doesn't have one.
I had trouble with discs not reading and wobbling so much that you could hear them scraping.
The magnet in the original is also much stronger.
Swapping them over made a big difference.
I had a scraping disc problem as well, when some would randomly load off-centre. Sounds like it's better to cannibalise old CD players for mechanical parts instead of getting variable quality chinese clones. That said, there appears to be absolutely nothing wrong with the laser.
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Old 17th October 2013, 10:15 AM   #19834
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In the interest of documenting the story for others, a tube of grease was delivered this morning - that electrolube SPG stuff. While taking the drive gear out to apply grease to the spindle and teeth, carefully inspecting the spiral gear revealed some sort of plasticky residue that had dried in there. I pulled it off with some tweezers I actually got for removing ingrown hairs. This could have been the root of the problem, but I'm not going to get too excited yet...
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Old 17th October 2013, 12:34 PM   #19835
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Quote:
Originally Posted by scumble View Post
I pulled it off with some tweezers I actually got for removing ingrown hairs.
I think that's probably best kept on a "need to know" basis

Old dried grease was the original problem of the CDM12 series pickups. It often became granular and jammed the gears.

A clean strip of paper soaked in iso and pulled through the gear centres is worth doing too.
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Old 17th October 2013, 07:35 PM   #19836
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Those tweezers have been a real help mind you.

I was beginning to lose the will to live with this repair job. I think I've taken it apart several times today.

I soldered the outer case of the VAM1201 back in with the only new part being the laser sled, added grease, removed it, inspected gear teeth

I realised that particles of dust probably can't stop the gears moving given the ratio on the sled motor. I had to think of the last thing that was a variable, because until the laser failed the VAM in the player had worked perfectly.

The last part that you can remove is the gear teeth on the side of the laser sled, the only remaining difference. It's held in by a piece of wire like a spring, which would have been hard to get in place without the tweezers.

After swapping that - no skipping in the trouble spots that have been annoying me for the past few days. I noticed that in service mode the sled got stuck before changing that part.

Still getting temporarily stuck in one or two places but it doesn't appear to be quite so persistent. Might even settle down now.
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Old 17th October 2013, 08:07 PM   #19837
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Default re transport

Having replaced many vam 1202s over the years i have not heard of one so problematic,may be ive been lucky.;

always one alan
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Old 17th October 2013, 08:38 PM   #19838
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I have completed about 10 CD63 modding project for my friends. For every CD63 I mod I normally disassemble the whole CD driver unit and have it thoroughly cleaned (gears, slides etc) and then re-grease. I did not encounter a lot of problems and usually the CD drive works again after some adjustment. May be I am also a lucky one.
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Old 18th October 2013, 06:12 AM   #19839
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A very rough and ready test is that an AVO 8 on its low ohms range (which uses a 1.5 volt battery) will send enough current to power the sled end to end when applied across the motor.

A good test is to monitor the voltage across the sled motor in play mode. If it suddenly starts to rise then it means the sled has stuck. The voltage continues to rise until the motor has enough torque to jolt the thing forward. If that jolt is too severe it jumps.
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Old 18th October 2013, 10:00 AM   #19840
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It's possible I had a particularly bad 1202 unit, maybe I should have sent it back. It's very difficult to know what sort of quality you're going to get, but it seems strange for such an industry standard unit. I'm guessing that these philips transports are used in many chinese manufactured CD units...

Unfortunately I don't have any test equipment - I'm not much of an electronics enthusiast, I just couldn't face binning perfectly good audio electronics because of a broken laser. I used to dabble when I was a teenager so the soldering didn't scare me off...

I didn't find anything in this thread about using more reliable transport units. I've seen that you can use expensive die-cast transports but is there anything in between?
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