Sony MDP-605 player woes...

[John Clifford]

I have owned this player since the mid '90s and it has always given me
excellent service... until recently. After not using it for a year or so, I
tried to put on a laserdisc and found that the picture was no longer stable.

I've heard that Sony players suffer from bad capacitors as they age, and
that seems like my problem. The symptoms are, the player operates correctly
and audio is fine. The video signal, on any output, is as if the unit was
losing vertical sync occasionally. I can hear the player's head hunt around
when this happens... usually the head mechanism only makes a ticking noise
when it's searching but I can hear the player try to correct for the head
misalignment.

I've tried the obvious things (cleaning the sensor, etc.) and no joy. I
think that the player is having a tough time keeping the head in one
position, which seems like a symptom of the 'bad capacitors' problem that
Sonys seem to suffer from. Could this be a slight alignment problem instead
that could be fixed by slight tweaking of one of the pots?

I believe I've identified the PC board that controls the mechanism... it is
on the right-hand side of the unit and is brown in color, and contains the
head adjusting pots, some chips, and a ribbon cable that runs to the head
mechanism thru a very small and very simple intermediate PC board mounted
just above the head assembly mechanism.

Because I can't find anyone who will work on this for anything approaching a
reasonable price, I'm going to try and fix it myself. Does anyone have any
experience actually fixing Sony LDP units with this problem/these symptoms?
Please, no advice on buying another laserdisc player... I have more than 50
LDs with some great titles that aren't available on DVD, but don't want to
sink a couple hundred dollars into someone else's used player that may or
may not work for any length of time.

My initial strategy is to pull this board and replace all the capacitors on
it, and then re-assemble the unit and see if that fixes the problem.
However, if anyone has actually fixed one of these units I'd sure appreciate
hearing about what they found was wrong.

Also, if anyone has a PDF or scan of the schematic and the service manual
I'd sure appreciate getting a copy.

You can email me at johnclif - at - ix.netcom.com (hopefully I won't get
spam, please fix to valid address), or post information to this thread.

Thanks,

John Clifford

[John Clifford]

After doing some more research thru the archives, could this be as simple as
a slipping spindle? How do I clean the spindle?

Thanks,

- jgc

[Kurtis Bahr]

If you want to try to clean the spindle first you need to clean the surface
on top of the spindle motor that touches the bottom of the LD. I do not
know how easy it will be to access. I use shamus swabs and Radio Shacks
Professional head cleaning solution. You really have to scrub hard to
resurface the rubber so it will grip.

Before you do this try a CD. If it plays OK then try cleaning, if it
doesn't play then you definitely have problems with the electronics.

Kurtis

Post by John Clifford
After doing some more research thru the archives, could this be as simple
as a slipping spindle? How do I clean the spindle?
Thanks,
- jgc

[John Clifford]

This post might be inappropriate. Click to display it.

[Kurtis Bahr]

If it has surface mount capacitors, look at those first after you verify the
voltages. I doubt the power supply is the issue.

Kurtis

Post by John Clifford
Okay, I tried cleaning the spindle and there was no difference... audio is
still great, video signal still suffers from jitter.
I've obtained a service manual for this machine, and am going to attempt
to fix it. I'd appreciate any pointers from the more experienced among you
out there.
This jitter (vertical picture instability) happens with either CLV or CAV
discs. From what I know about LDs (which is darn little), CAVs have one
frame per track, so jitter is caused by some aspect of head misalignment.
In my circumstance, I believe it is caused by very small, random
fluctuations of the optical head assembly. I am hypothesizing that this is
caused by some sort of voltage wandering, i.e., these players don't have a
stepper or servo mechanism that indexes the head neatly but instead the
head's location is a function of a voltage being applied, and the head
position (in or out) varies as the voltage varies. Therefore, my unit has
an unwanted fluctuation in the voltage that controls the head position and
therefore the head moves back and forth slightly. This sounds exactly like
something that would be caused by a bad capacitor.
I'm going to try to look at all of the DC voltages that are produced by
the power supply on a scope and see if any have a waveform associated with
them, and if so I may try to shotgun replace all of the capacitors that
affect that circuit. If that fails, I'm going to try to trace the head
assembly control voltage back to its source and see where the fluctuation
starts.
Does this sound like a good strategy? If not, I'd gladly welcome any advice.