Hmmm. The plot thickens.

 Since I'm very low on patience when I get my head stuck into something - I decided to try something else. So - looked in the danish equivalent of Craigslist (funny how that became the term) and found a Philips CD162 for the hefty sum of 50 DKK (around €6.5) - went and picked it up as the seller claimed it worked when it was put away 6-7 years ago when they moved)

Stuck in the offending CD (Singles Soundtrack) that's been giving me issues. Lo and behold. It plays the CD perfectly. No skipping, no ticks, it just plays (even at low volume on CX100s, it doesn't sound like the BG7000 that's for sure).

So. With the build quality of the unit, it takes all of 30 minutes to have the CDM-4/19 drive out. An hour later, the laser unit is mounted in the BG7000. I do all of the adjustments according to the manual. Focus voltage to 400mV +/- 40mV (39 measured on my crappy meter). 40mV on the laser in Test Mode 2.

All four test modes passes with flying color!

In the service manual under laser adjustment, it says: (In service position 2)

"Adjust 30R3106 until the voltage across 30R3102 is about 40mV".

(This voltage varies when the disc is rotated).

Leave service position 2 by switching off the mains briefly.

Play track 1 on test disc 5.

Adjust 30R3106 until the voltage across 30R3102 is 50mV +/- 5mV.

The 40mV I can get spot on. BUT - if I keep the voltage around 35-38mV across 3102 when it's playing, it's almost ballpark - if I turn it up to 50mV as it says in the manual, there's lots of skipping noises.

Could it be something on the servo board. IC6101 having a really bad day?.

Thank you all for your invaluable help,
/Confused in Copenhagen

[EDIT:] That's annoying!... Put the CD162 back together with the laser from the BG7000 and a minimum of screws to hold it together. I don't even think I tightened the 2.9mm bolts holding the laser in place come to think of it.

Power on. Annoying CD in the drive. Hit play. It just works. Haven't even touched focus or laser power pots.... I'm beginning to think our friends in Struer over complicated the drive part of the players more than they had to.....

Are all supply voltages correct and clean?
Are you using the SONY YEDS-5 test CD or the 5/5A-set from Philips, that B&O once supplied?

Martin

I sincerely hope I didn't give anyone the impression that I have the slightest idea what I'm doing - because I mostly make it up as I go along :D

No. But at least I've been using the same CD when doing the measuring to keep those as equal as possible. Don't have access to neither of those CDs.

I will be checking the supply voltages next and post the result. I does look like it improves when it gets to up to temperature though. Have been through 4 old Alice in Chains discs this afternoon (bought in their hey-day, so old slightly worn discs) and it mostly behaves with only small clicks now and then

BR, and again, thank you!

You cannot use an ordinary audio CD for aligning the drive.
They are far too different, they wobble, skew, runs off center etc.
You can easily tell the difference from an ordinary audio CD to a real test-CD just by looking at the physical laser lens focus and radial balance movements.

The worst thing you've done so far is messing with the trimmers.
DON'T ADJUST ANYTHING ON THAT SERVO BOARD - unless you know EXACTLY what you are doing!
The problem with these drives is almost always capacitors - and occasionally excess ripple on the supply voltages.
The lasers practically never die.
- Unless messed with...
It takes no more than 1/10th of a second of twice the recommended laser current to burn the laser - and the laser
current adjustment trimmer (unfortunately) allows for FAR MORE than that.
In other words, it's NOT SAFE to touch that adjustment - the laser WILL go black very fast if the current is set too high.

In your case, I think it's safe to say, that one of the beams has gone weak.

Imagine having a car on auto-steering running on a white line on the road.
Two sensors, one on each side of the car.
If one sensor sees the line, the steering of the car is corrected to that side.
When one sensor dies, the car may run and follow the line within reason for some distance, but it will eventually run of the road.

Martin

I might not have any idea what I'm doing, but that doesn't mean I can't read a manual ;)

Since I'd already swapped the 6 caps and that didn't fix the problem - I picked up the old Philips CD162 and swapped the laser. And in the manual, it does say, that when replacing (in my case, swapping for a used part), you have to set a baseline for offset and laser current. So I did as it says in the manual, and set laser current to 40mV and offset current to 400mV.

I would never touch anything without having understood the procedure, and since I now have the original laser safely stored (in the CD162) and HAD to make a baseline setting, I can't see how I could avoid touching the pots?.

Funny thing is - when I first measured the laser current after swapping the laser (it read 49 with the old one), it read 23mV - so of course the player would just go into standby as it had zero chance of reading anything - whatsoever. I also find it strange, that the best result with the least "artifacts", was with the current at around 42-43mV, and not the 50mV it says in the manual.

Anyway - as said, I will look at the stability of the supply when I dig the scope out of the closet.

Hmm. PSU seems fairly solid to me. Supply voltage measured at socket 33 of course:

(Top Left (-9.5V), Top Right (-6V), Bottom Left (5V), Bottom Right (9.5V))

Full image: