Audio Note CD3.1x FAIL ... false alarm

[Nick]

Did the replacement laser include the motor?

It may be that the centre of the motor spindle (what the disk sits on) doesn't match the puck that comes down and clamps the disk in place.

When I get that, I take it out again, and replace the laser sled on the old transport with the one from the new transport, so you have old motor and new laser.

[IslandPink]

Ah right , tolerances on motor centre not too great then ?
I can do this ... tomorrow.
Thanks.

Just need to make sure I avoid static while the laser is now un-protected.

[Nick]

Its not tolerances, its the shape of the centre platter, there are different designs that will only fit the matching puck.

[IslandPink]

The two modules are identical as far as I can see , particularly the 'wheel' that sits under the CD . There is one area of adjustment and/or uncertainly though . The motor/laser subboard ( metal ) fits into a plastic carrier via four small screws, springs and rubber conical washer things that are like shock absorbers, at each corner. If these are not all carefully fitted and identical at all four corners it might pull the sub-board a bit one way or the other.
I will have another look .
Changing either the laser or the motor assembly off this unit looks HARD, from careful inspection of the old unit. The laser 'block' would have to come apart into several pieces and I'm not sure the little PCB flexi bits would disengage from all the mechanics. The motor bits have screws that are inaccessible without taking the 'wheel' off the end of the CD drive motor . Not sure I want to risk that .

[Nick]

Yes, it needs to sit properly in the corner mounts.

Changing the motor is possible, I have done it several times, but it looks worst than it is. The flexible connector pulls out and the metal rods that it slides on pull out freeing the laser sled. But if the centre is the same then its not that.

[IslandPink]

Ooh, you little tinker . There's a clip at one end of the rod that allows you to remove it and take the entire laser block off. Very interesting !

[IslandPink]

Well I've spent ( wasted ? ) another couple of hours on this job today .
I was able to remove the rod and the laser assembly from unit 2. It was odd how easy the laser 'block' came out, and how damned near impossible it was to put it back through the hole of unit 1 ( original ) . Talk about a 3D puzzle ! - in the end I loosened the small PCB that's on the laser unit to allow a bit more freedom of movement - otherwsie I'd never have done it .
So I then had to put the metal frame back onto the plastic ( larger ) carrier, using the screws/grommets I mentioned last time.
Here's when I noticed something interesting ( see pic ) . The springs are not the same rate . There are 'silver' springs and 'gold' springs . The gold ones are stiffer.
I have no idea which way round the springs were on the last rebuild, but this time I put the gold ones at the end where there's most weight, from the motor units.
So, now I have laser unit 2 ( new ) and the motor/carrier/wheel from unit 1 ( original ) .
All seemed well on switch-on on the kitchen table. I tried the discs I'd used yesterday , including 'Bryter Layter' which was scraping on every rev. and wouldn't play. All discs span nicely .

So I went through to the front room and put the CD player into the system and tried it . Oh dear - the discs all play up to a point, but skip from time to time . Even the very good John Renbourne collection which I played right through, yesterday , now skips .
I wonder what the next step is ?

[pre65]

I wonder what the next step is ?

[IslandPink]

That's definitely one option

[Nick]

This link here shows one solder link, I wonder if the second one you removed should have been removed.

http://www.aliexpress.com/store/product ... 63568.html

[IslandPink]

No, it's OK, the other solder link is on the PCB for the motors . I checked both against the original unit and both needed to be removed. When I first put in the replacement unit ( complete ) the motors didn't work. That was fixed by un-connecting that other solder bridge.

I'm starting to wonder if the original unit was failing because of the motor . The jumping and 'No disc' errors I'm seeing today were what caused me to buy the replacement in the first place .
If the second unit ( complete, as used yesterday ) was working fine apart from the CD's scraping a bit , maybe I need to put the No.2 laser unit back into the No.2 frame&motors .....
The CD scraping problem seems most likely due to me not understanding the different spring rates, and the CD's hence being out of kilter.

A job for later today after a walk, I think .
Sun's out !

[IslandPink]

No dice
Laser 2 and motors 2 installed now, with springs in correct positions.
Discs don't scrape. For about 45 sec I thought it was working fine and the dulcet tones of track 1 on Bryter Layter rang out ; then it jumped. After that it carried on jumping every few seconds. The Renbourn collection which played yesterday all through, gives 'no Disc' some of the time or starts OK, but starts jumping as per the Nick Drake one.
There must be some other set-up parameter or tweak I don't understand about the mechanism .

[IslandPink]

http://www.repairfaq.org/sam/cdfaq.htm#cdoldsor
perhaps I damaged something in the gears when putting the second laser unit back into its original carrier ?

[IslandPink]

Of fer 'ck's sake - the laser carriage bearings and rod must be paired for tolerances to get a good fit without being too tight . I noticed it was hard to slide the rod ( not sure if this was from unit 1 or 2 ) through the laser carriage holes on this afternoon's rebuild . Checking the no.1 laser block and the remaining rod , on the kitchen table, these are a very easy, almost loose fit.
Re-build No.5 coming on ....

[IslandPink]

Re-build 5 completed - carriage rod swapped.
Playing now - it fooled me into thinking it was fine for over a minute ; then jumped. Maybe it just needs a bit of grease on the rod ....