(Depending on drive version) check the ribbon cable for breaks. Especially where it is held by the black plastic holder before it runs in
an arc to the swinging laser block.

Martin

My doesn't have a black tab, but I do have a ribbon cable that twists and connnects the pcb (where the cap is on) to the drive.  It looks OK but this evening I will test connectivity on each of the tabs.  

I'd appreciate help with the following questions:

1) on the spindle motor I have a port/plug with 4 wires - can someone help me understand what those wires are - I want to get my multimeter to test if power is being sent to the motor to help me diagnose - also want to feed it power to confirm the motor turns but don't know which of the 4 terminals I need to use (which is pos which is neg) and how much DV power to feed it.

2) is the lense supposed to move up and down for focus?  As mentioned when I first hit play the lense swings to around the outer edge of the disc (and I see a red light out the lense) but from there nothing more happens.  I believe the lense needs to focus and then the motor turns on - to focus is the lense supposed to move up and down - is this right?   How do I test the focus or adjust it  

Thanks

1. Not easy to replicate the motor signals on the bench. If it's the version I have in mind, the four pins are a positive voltage, a negative voltage, a control signal and a ground.
The two motor coils are controlled by some opamps running through 4-phases, some hall elements for feedback and four driver transistors.
Look in the schematics. This rarely fails.

2. Yes, it should move up and down by apprx 1-2 mm while seeking focus. If it doesn't move, check the ribbon cable connections and traces that runs to the focus voicecoil. In my experience this is more likely to fail.

Martin

"(Depending on drive version) check the ribbon cable for breaks. Especially where it is held by the black plastic holder before it runs in

an arc to the swinging laser block.

Martin"

So after removing the cover and looking closer I see the black plastic holder you are referring to - how do I remove that plastic holder?  Do I just pull up on the little tab on top of the holder, or do I need to pinch the arms on the bottom?  Just want to make sure I don't break it.

Second, it is hard to see but it doesn't look like the ribbon cable connects together at that arc but instead the black holder is intended to let the ribbon cable bend - is that correct - just want to know if the bend has a connector to join two ends together is it is still one cable from the little pcb board all the way to the lense and lense pcb?   If one cable, how do I test this cable - easy enough on the main flat side as the tabs are all there once pulled out from the little pcb but on the other end they branch out all over the place - would like some advice on how to test this cable?   Is this cable also a common fail area?

Thanks

Just pry one of the holders pins inwards (the one that has most room for it) and lift out the holder.
Note the way it goes in.

There is no joints under the holder - only a bend, and right there where the holder pushes down in the cable, the cable can sometimes break - particularly
if it was pulled inadvertently during f.e. cap replacement.

Martin

"the cable can sometimes break - particularly

if it was pulled inadvertently during f.e. cap replacement.

Martin"

Thanks - I'll try that tonight.  Though a little confused about the comment that the bended cable can sometimes break during cap replacement.  The cap is on the servo pcb which doesn't even attach to the cd mech - the servo pcb attaches to a small pcb through its own ribbon cable - it is that small pcb then that has a 2nd ribbon cable connecting to the cd mech.  So when I did the cap replacement I only moved the servo pcb which doesn't have any impact or movement to the cd mech.  Just curious if we maybe are talking about different sections?   

Also what is the best way to test this 2nd ribbon cable.  As mentioned in my message above it is easy to test the end that connects to the small pcb as it is flat and once removed easy to put a multimeter on but on the other end it branches out to all sorts of sections and many are not accessible.  I assume I need to remove the swing arm of the lense??

Thanks

Correct, but the servo board sits under the drive in some decks (Beocenter 9000 etc.), and it can be difficult to get to the connector to unplug
the ribbon cable without pulling the cable.
And I have actually seen the same breaks develop in CD3500/4500, even if you really don't have to pull the cable. 

Don't remove the swinging arm. Just follow the traces in the cable and check for continuity, one by one.

Martin

So today I tested this 2nd ribbon cable with my multimeter - I tested every tab on the flat side for continuity on the other side it lead to - unfortunately all wires were good - I repluged it back in and still same issue.  Lense arm swings around but I don't get any focus movement and the motor never kicks in.  I find it I hit the scan button the cd turns about 1 millimeter then stops then again turns 1 millimiter and stops and then goes to standby mode.

Looks like this one beat me, as I'm out of ideas without being an electronic tech with more specialized tools.  I guess I'll keep my eye on ebay for a parts unit and hope to eventually do a swap of the entire cd mech