A colleague asked me to apply my repair skills to a Pioneer CLD-2950
laserdisk player, which he bought cheap on Ebay (should know better!)

The PSU was tripping out due to overcurrent which I traced to a
shorted TA8464K power amp which drives the focus/tracking. With this
chip removed, the machine ejects/loads etc, the sled runs, and it
turns the laser on for focus search (won't lock, obviously) which I
thought was hopeful.

I got a new chip. Thought I'd check the focus/tracking coils weren't
shorted before I power on as I don't wish to fry the new chip.

Ugh! Both are open. Lifting the plastic cover from the voicecoil
assembly, I find one of the 4 suspension wires loose (unsoldered)
which explains the open focus circuit. The tracking coils look rather
fried.

I wonder if the chip failed and blew the coils, or the coils shorted
and blew the chip? The loose wire is presumably someone tampering,
I doubt it could have unsoldered itself, unless it was very badly
attached at the factory.

My usual UK sources (CPC, Grandata) don't stock this pickup. Can
someone suggest a source (UK preferably, European or US otherwise)
that would still have one for this rather old technology, preferably
at a sensible price. I don't know if the voicecoil+lens+suspension
might be available separately, it comes out readily from the rest,
one screw after the flex is unsoldered from it.

Can someone who knows this machine or has documentation give me
some guidance please. Knowing the part numbers of pickup and/or
voicecoil+lens+suspension would help ordering the right bits.
(Or a scan of the relevant page of an exploded diagram / parts list.)

Better yet, is there anyone out there with a dead Pioneer optical
block that I could scavenge parts from? One with a dead laser might
be ideal to me as I think the laser is OK in mine (it certainly
comes on).

As a last resort I might have a go at repairing the coils. I know
that wouldn't be considered by a professional, but I do repair as a
hobby (I design chips professionally) and am willing to spend far
more time on it than it really deserves - I hate to be beaten and
feel I've invested too much time (and some money) in debugging this
to give up now!

Thanks for your help.

Regards,
Mike.

www.ardelectronics.co.uk or it might be .com ........

Used to sell a wide range of lasers but have been clearing old stock as
clearance items lately, if you contact them they may have one lying around
that you could buy cheaply.

--
Pete Cross

"Remove _ for valid address" wrote in message
...
A colleague asked me to apply my repair skills to a Pioneer CLD-2950
laserdisk player, which he bought cheap on Ebay (should know better!)

The PSU was tripping out due to overcurrent which I traced to a
shorted TA8464K power amp which drives the focus/tracking. With this
chip removed, the machine ejects/loads etc, the sled runs, and it
turns the laser on for focus search (won't lock, obviously) which I
thought was hopeful.

I got a new chip. Thought I'd check the focus/tracking coils weren't
shorted before I power on as I don't wish to fry the new chip.

Ugh! Both are open. Lifting the plastic cover from the voicecoil
assembly, I find one of the 4 suspension wires loose (unsoldered)
which explains the open focus circuit. The tracking coils look rather
fried.

I wonder if the chip failed and blew the coils, or the coils shorted
and blew the chip? The loose wire is presumably someone tampering,
I doubt it could have unsoldered itself, unless it was very badly
attached at the factory.

My usual UK sources (CPC, Grandata) don't stock this pickup. Can
someone suggest a source (UK preferably, European or US otherwise)
that would still have one for this rather old technology, preferably
at a sensible price. I don't know if the voicecoil+lens+suspension
might be available separately, it comes out readily from the rest,
one screw after the flex is unsoldered from it.

Can someone who knows this machine or has documentation give me
some guidance please. Knowing the part numbers of pickup and/or
voicecoil+lens+suspension would help ordering the right bits.
(Or a scan of the relevant page of an exploded diagram / parts list.)

Better yet, is there anyone out there with a dead Pioneer optical
block that I could scavenge parts from? One with a dead laser might
be ideal to me as I think the laser is OK in mine (it certainly
comes on).

As a last resort I might have a go at repairing the coils. I know
that wouldn't be considered by a professional, but I do repair as a
hobby (I design chips professionally) and am willing to spend far
more time on it than it really deserves - I hate to be beaten and
feel I've invested too much time (and some money) in debugging this
to give up now!

Thanks for your help.

Regards,
Mike.

Lifting the plastic cover from the voicecoil
assembly, I find one of the 4 suspension wires loose (unsoldered)
which explains the open focus circuit. The tracking coils look rather
fried.

Which means the pickup is definitely shot, yes?

Very bad news. As you know, locating a replacement pickup isn't easy, but
that's just part of the difficulty.

First off, the optical pickup is an entire module; its parts are not available
separately and would be impossible to install properly at a repair shop as
pickups are assembled to exacting tolerances.
The only exception is with very old LaserDisc players that used large HeNe gas
tube lasers, external optical components, and external photosensors. However,
the CLD series all used small semiconductor lasers along with the optical
components and the photosensor arrays and all integrated into a single modular
pickup assembly.

The other part is that, once you do find a replacement pickup, you have to
calibrate it. You can't just slap the new pickup in the player and expect it
to work instantly.

Properly calibrating the pickup on a LaserDisc player requires the correct
Pioneer service/calibration LaserDisc, the proper service literature, an
oscilliscope, the proper tools, and the proper training.

You have to calibrate the pickup and the player electronics to get it to work
with the player properly. This is all work that will easily exceed the value
of the player. The pickup alone, if you can find one, will sell for more brand
new than what a fully functional CLD-2950 is worth!

Besides, there are probably other problems with the player that has caused such
a catastrophic failure to the IC you replaced and to the optical pickup.

Unfortunately, I would recommend that your friend keep looking for a working LD
player. - Reinhart

In article , Pete Cross wrote:
www.ardelectronics.co.uk or it might be .com ........

Used to sell a wide range of lasers but have been clearing old stock as
clearance items lately, if you contact them they may have one lying around
that you could buy cheaply.

Pete, Thanks for the pointer. (It's .com by the way.) Sadly they inform me by
email that they no longer stock any optical pickups.

Mike.

--
Pete Cross

"Remove _ for valid address" wrote in message
...
A colleague asked me to apply my repair skills to a Pioneer CLD-2950
laserdisk player, which he bought cheap on Ebay (should know better!)

The PSU was tripping out due to overcurrent which I traced to a
shorted TA8464K power amp which drives the focus/tracking. With this
chip removed, the machine ejects/loads etc, the sled runs, and it
turns the laser on for focus search (won't lock, obviously) which I
thought was hopeful.

I got a new chip. Thought I'd check the focus/tracking coils weren't
shorted before I power on as I don't wish to fry the new chip.

Ugh! Both are open. Lifting the plastic cover from the voicecoil
assembly, I find one of the 4 suspension wires loose (unsoldered)
which explains the open focus circuit. The tracking coils look rather
fried.

I wonder if the chip failed and blew the coils, or the coils shorted
and blew the chip? The loose wire is presumably someone tampering,
I doubt it could have unsoldered itself, unless it was very badly
attached at the factory.

My usual UK sources (CPC, Grandata) don't stock this pickup. Can
someone suggest a source (UK preferably, European or US otherwise)
that would still have one for this rather old technology, preferably
at a sensible price. I don't know if the voicecoil+lens+suspension
might be available separately, it comes out readily from the rest,
one screw after the flex is unsoldered from it.

Can someone who knows this machine or has documentation give me
some guidance please. Knowing the part numbers of pickup and/or
voicecoil+lens+suspension would help ordering the right bits.
(Or a scan of the relevant page of an exploded diagram / parts list.)

Better yet, is there anyone out there with a dead Pioneer optical
block that I could scavenge parts from? One with a dead laser might
be ideal to me as I think the laser is OK in mine (it certainly
comes on).

As a last resort I might have a go at repairing the coils. I know
that wouldn't be considered by a professional, but I do repair as a
hobby (I design chips professionally) and am willing to spend far
more time on it than it really deserves - I hate to be beaten and
feel I've invested too much time (and some money) in debugging this
to give up now!

Thanks for your help.

Regards,
Mike.