WEIRD problem with CD player

[Mark D. Zacharias]

Sam Goldwasser wrote:

<Snip>

The entire pickup moves to do tracking.

The entire pickup moves only when the tracking error reaches a certain
point, at which time the pickup is bumped a bit, and the tracking coils
re-center. Unless we're talking about an old Philips pivoting pickup with no
tracking coils...

But I'm pretty sure you knew this anyway.


Mark Z.

 

[Sam Goldwasser]

"Arfa Daily" <arfa.daily@ntlworld.com> writes:

bill@bird.peck> wrote in message
news:6msip2p001orojks2g0ui2htpo5cv9ecen@4ax.com...
I don't know if I will ever get this working right, but I sure am
learning a lot.

I'm sure this has to be looking for a reflection before it decides to
starts up the spindle.

I can't see the lens with the CD in. If I put a clear protective disc
in, nothing happens because it sees no reflection.

The unit is a CDP-302, a high end unit. The tag on the laser assy is
BU-1
119712

And from its construction, to replace it might cost the same as what I
paid for the unit new.

Since it will play in any position once started, is it possible the
focus/tracking drive isn't working till it starts and the at rest
position is causing the reflection to totally miss the target.


I can only imagine that to be the case if the disc was not lying flat on the
turntable for some reason. That laser part number is not familiar to me.
I'll see if I can find some service info on this player, and see if I can
think of anything else that you could reasonably try. It's reaching the
point where you have to be starting to think that it's something obscure
rather than common. An experienced eye might just look at it, and see
immediately what the trouble is. On the other hand, sometimes faults like
this can baffle even the most experienced of us.

I agree it may be obscure and possibly an electronic problem. There are
some differences in the part of the circuit used for the focus seach, so
your hypothesis is at least possible.

What I have done in the past to examine what's happening when it tries
to focus is to cut down a normal CD to just larger than the inner track.
One of those mini-CDs might also work. If you see the lens not moving
up and down very far, then initial focus search may be the problme.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
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[Sam Goldwasser]

"Mark D. Zacharias" <spammenot@nonsense.net> writes:

Sam Goldwasser wrote:

Snip
The entire pickup moves to do tracking.


The entire pickup moves only when the tracking error reaches a certain
point, at which time the pickup is bumped a bit, and the tracking coils
re-center. Unless we're talking about an old Philips pivoting pickup with no
tracking coils...

No, not those! Anything but those!

But I'm pretty sure you knew this anyway.

Right, it was in direct reponse to the original question but perhaps the
reply didn't quite make it intact.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

 

[tomh]

I re-attached a lens just the other day, but have never tried using one
from another brand pickup. If I don't find the original rolling around in
there, I just consider it a lost cause.

BTW I have found that Pioneer lasers which oscillate have the lens coming
loose but hasn't fallen off yet.

I don't use superglue because of the danger of it fogging the lens.

Mark Z.

Point taken on the lens fogging. It actually happened to me on one of the
first that I tried to reattach some years ago. That is why I now only use
the tiniest drop, and let it draw itself into the gap. Fuming and fogging is
then not a problem. Next time you get a missing lens, just give a Sony one a
try. If it's a lost cause already, you've got nothing further to lose !

Arfa

Hmmm, I've got a PS2 with a lens that has bubbles and scratches in it.

I was thinking about trying a lens from a compact stereo CD unit I just
shredded for parts. I realize its CD vs DVD but the lens's look the
same. As observed "got nothing further to lose !"

 

[b]

tomh ha escrito:

Hmmm, I've got a PS2 with a lens that has bubbles and scratches in it.

blimey, what do you do to it? set it on fire then put it out by
scraping it with a nailfile??!! ;-)

 

[tomh]

b wrote:

tomh ha escrito:

Hmmm, I've got a PS2 with a lens that has bubbles and scratches in it.

blimey, what do you do to it? set it on fire then put it out by
scraping it with a nailfile??!! ;-)

it was "broken" when I got it. The scratches I can see from somebody

previously getting in there and fooling around. Which they did. But the
bubbles they've got me stumped. If I manage to get a picture of the lens
I'll post it.

 

NO, I have pushed it to be sure it is all the way in.
The tip is from side to side so gravity is not at work here. A front
to back tip will not cause it to operate.

Also, it will only CONTINUE to play in any position once play is
started. If I tip it to read the TOC then lay it flat it will not
start playing.

I HAVE discovered something else.
The sled rides on 2 rails. one side has a sleeve on it, the other
rests on a roller. It will move up about 1/16 inch on that side. If I
try to start it while flat AND holding that side up it works. Once
started, I have to let it go so the sled can move and it continues to
work.
Since that is not giving me a 45° tip, it does point to the lens or
something inside being too far off to see the reflection in its normal
position. Since it comes back at a 45° tip I have to think something
inside is loose rather than the lens gimble as that only seems to move
in the plane of the CD. HOWEVER, there isn't anything else in the assy
that moves except the lens is there??????????
THEREFORE, it has to be the lens gimble, RIGHT?????????



On Wed, 03 Jan 2007 10:38:44 GMT, "Arfa Daily"
<arfa.daily@ntlworld.com> wrote:

bill@bird.peck> wrote in message
news:fbcmp2lsfk90veotdu8ua4bh23lv8vplrv@4ax.com...
I've tried so many things, I probably looked at that.
There is no restraint on the sled. It moves freely.
The drive belts for the table are weak, but I twisted them and it
seemed to work ok. I made sure it was fully seated when closed. It
wouldn't clamp the CD if it wasn't. I have watched it seeking track 0
but I don't remember if that was only when tipped or if it did it when
it was flat also. I believe there was no action whatever when it is
flat, but I will look again.
I can't see the lens assy from the bottom, but I will try a small CD
and see if I can view it then.

thanks.

Well, if the tray drive belt is weak, then the very first thing I would do
is to replace it. I wouldn't for one second believe with absolute certainty,
that the loading cycle is completing correctly and fully, just because the
disc appears to clamp. I have had similar situations many times, where the
final push of the mech, beyond just clamping the disc, works a "load
complete" switch, and that extra little bit of mechanical resistance from
the switch's spring loading, is just enough to hold it open. If, as you
suspect that you observed, the deck does absolutely nothing when it is flat,
then this would be a good indicator that the system control micro is waiting
for something like a "load complete" signal. In this situation, gravity may
well take over to assist the last little movement, when the deck is tipped.
This would also make sense with your assertion that once the deck has read
the TOC 'on the tip' as it were, it will then play in any position. The
system control micro only needs to be told that loading is complete, once.
Just change the belt, before going any further ...

Arfa