Causes of CD player skipping?

moolimbo,

Not so weird. I had a favourite CD player I had bought new in 1989 or 90 (Sony CDP-670) that started to skip in 2005 after a move. I ended up buying a really nice new Marantz to replace it. However, I kept the old Sony as it had a great Brown and Burr DAC in it and it sounded great otherwise.
Three years ago (2016), having moved a 2nd time, I decided to set up a 2nd stereo in my den and hauled out the old CD Player and thought ’why not try and fix it’. I went and read this excellent resource https://www.repairfaq.org/sam/cdfaq.htm and tried all the tips and tricks. I concluded after trying everything that either the laser was bad or there was a tiny crack(s) somewhere in the board. Because it had seen high use I gambled on it being the the laser and ordered a new high quality replacement and had a repair guy I trust put it in. He lived in my previous city so had to wait for a visit opportunity to get it fixed. I spent about $80 on the laser and repair. Then I drove the repaired player home (a 5 hour drive) plugged it in and arghh ... still skipping. So I put it away for 2 more years regretting I had even tried to fix it.
Last month with a little more time on my hands I hauled it out again and took it apart. I switched the cart out with one from a working thrift store Sony CDP-470 (lower model with no Brown and Burr DAC) ... but ... it still skipped. So I knew the problem had nothing to do with the cart/new laser. So I switched them back again. What struck me was that the skipping would happen on its own but also if I walked too fast by my CD Player (laminate on a basement floating floor)
So, I went back on line and read this thread. On a whim, after reading your post, I looked at the bottom of my CD player. Guess what? One of the little rubber 1/4 inch thick foot pads was missing from the back left side - probably knocked off during my move in 2005. So I took a pad from the CDP470, glued it on the 670 and ... yep .. you guessed it. CD player works like a champ. I have run it hard for 40 hours or so with no issues. I can also now walk beside it without causing skipping.
So my theory is that with the missing foot pad the plastic chassis was flexing up to a 1/4 inch which was enough to either 1) disrupt the movement of the optical assembly on the track/rails, or 2) flex the circuit board which may or may not have a crack in it I can’t see. The problem would have been made worse by having an EQ placed on it (added weight).
Since discovering this I see other posts complaining about the cheap feet on many CD players and the benefits of isolation products. So I have now ordered some sorbothane isolation circular discs. In the future I will also make sure my CD players are kept perfectly level, just like my turntable.
Moral to the story: Sony and many other CD makers used plastic cases/chassis. They bend. This can effect player performance so be sure this is not your problem before you take more drastic repair steps if your CD player starts to stutter, skip and jump backwards to track 1 (the symptoms I had).

So here's a weird one-
I cleaned and re greased the optical rails on my 200 CD Sony. Still skipped. As I was moving it, I lifted the back left end up (where the optical assy is located) which took the weight off the back left foot. It started playing fine, no skipping. I then Placed a spacer under the back side, just enough to take the back left foot off the tabletop. So far is playing fine.
Somehow the back foot of the case is tied in and stressing the optical assy to go out of alignment(?)
It's playing, so don't care at this point.

Sony CDP-CX300 skipping - terrible skipping problem solved 

(modified post repeated for clarity)

I applied gun oil (a thin oil that says it has silicone in it) with a Q-tip to the single metal laser guide rail. That eliminated the skipping problem. Such a simple fix: remove the cover, dab a small amount of oil on the rail. Amazing that something that simple solved the skipping problem. I had observed that CDs always started skipping between 4.18 and 4:54 minutes. That was an indicator of a "location problem".

Detail: Remove the cover. Visually look for the metal guide rail (shaft). It is located at the rear left of the player (where the laser movement mechanisms are located) when looking from the front, and is seen in between the black plastic. The laser mechanism slides on it and this can be observed by powering the unit, selecting a disk, then increasing & decreasing track numbers on a rotating disk - the laser will slide on the rail. Now, reach into the access to the metal guide rail with a Q-tip moderately saturated with oil (3 in 1, gun oil in my case), and wipe along the accessible surface of the metal guide rail surface; the "backside" of the rail opposite the access area cannot be be reached for lubrication without further disassembly. But reach around "behind" the rail as far as practical. This lubrication task is very easy to accomplish and should have been included in the manual.

I had previously done some disassembly and cleaned the black "split drive rack"(gear), then re-lubed it with white lithium grease. [The pinion gear (not seen) and rack move the laser on the metal guide rail]. This lubrication did not solve the skipping problem.

These players are not sold any more, but it sure is convenient to load up as many as 300CDs - and avoid e-wasting an otherwise useful CD player.

Very good advice here guys. Thanks! for sharing.

from Enco Systems:
Tribol Molub-Alloy 9890 grease is the lubricant recommended by Philips for use on the CD Pro family of modules
0.35 oz of Tribol 9890 grease is shipped to you in a narrow-tip syringe
Application of the very small amounts required on lubrication points is easy with this syringe. If it is worth change the lens and also make sure you lubricate the rail.

Claude  

Skipping
The player executes normal track play, but the music drops out or skips ahead or backwards, or gets otherwise garbled, during play. You might hear some clicks as the CD Pro attempts to track properly. This type of tracking problem is usually referred to as “skipping,” and may indicate that the CD Pro’s laser current is diminished or that its receptor diodes are failing. It will have particular difficulty reading low-reflectivity discs (e.g. CD recordable and rewritable discs) and discs that may not conform to Red Book specification (e.g. pirated discs or non-major label discs).

Sony CDP-CX300.

I applied with a Q-tip gun oil (that says it has silicone in it) to the single laser guide rail.  That solved my skipping problem.  I observed that the CDs always started skipping between 4.18 and 4:54 minutes.  That was a clear indicator of a "location problem".

I had previously done some disassembly and cleaned the "rack", then re-lubed it with white lithium grease.  This did not work, tho I got a good view of the laser guide rail on the laser assembly that I removed to lube the rack.

To lube the guide rail, I removed the cover, then reached into the access to the guide rail with a Q-tip moderately full of the oil, and wiped the accessible surfaces; the "backside" of the rail opposite the access area could not be reached for lubrication.  The access point is located at the rear left of the player when looking from the front, and in between the black plastic.  Look for the shiny shaft.

There has been many years since previous posts, but those posts were helpful to me.

Wow, nice call Davehrab.

I used to have a decent Sony player that I ditched when it developed a similar problem.

Well, you learn something new everyday....

I'll keep it in my hat for future reference!

I found the correct grease.
Search for CDM9 grease on eBay.
Good luck

BEWARE:
CD player gears and the plastic sliders that run atop the rails are made of nylon or Delrin.
DO NOT use regular household oil, 3 in 1, WD40 or any oil with solvents on plastic gears/sliders. WD40 has paraffin in its formula and will leave a sticky deposit.

Most of those lubricants start a chemical reaction with nylon and eventually the nylon part will crack or break. It may take a couple of years but it does happen. If in doubt read the Philips CD player service manuals.

There is a grease made specially for lubricating CD/DVD/VCR nylon parts. It is available through electronics parts stores/distributors.
White lithium grease from Home Depot is OK too, it does not attack plastic parts.
It is also available from Auto Parts stores and on ebay, search for white lithium grease. Avoid the ones mixed with molybdenium, they mess up the parts.
Use sparingly, apply a very thin film with a Q-tip.
Good luck

Hello, I have the SAME problem as you did.
Can you piont out to me where the Guide
rails are on a Sony CD changer?
Do you have a service manual?
Let me know. Thanks.

Update.
It worked!!
I took the cover off, cleaned the rails, lubed them, and the player works perfectly normal now.
Thanks to all of you for saving me some major bucks at the repair shop!
I called the local repair shop Wednesday and they told me my laser assembly was bad, and that it would cost a minimum of $200.00 for parts and labor!
Thanks again to all of you.

Lube those rails!

3 in 1 light oil worked for me.

I agree with Dave.
I had the same symptom on my old Yamaha cdx1030 (18 years old and my son is still using it). I used wd-40 to clean the rails then light oil to lub them.
Note: Dont use too much oil so wipe off any excess.
Good Luck

If it is indeed the laser guide rail lube that is dried up,
what kind of lubricant is used to relube them?
Thanks for your replies so far.

There may be some hope for your Sony yet ...

Sometimes CD players will skip when the factory lubricant on the guide rails that the laser rides on dries up.

When the laser sled comes in contact with the dried up lubircant patch on the guide rails ... it binds up and stops momentarily ... losing lock with the CDs Datastream and skips ... once past the spot where the dried up Lubricant is stuck to the rail ... the laser will regain lock with the data stream ... and the player plays fine until you hit the next patch/spot of dried up lubricant

This sympton is very common with older Cd players that get heavy use ... the LUB dries up

If you're handy ... just remove top cover to see if you can see the guide rails and clean them thoroughly before re-Lubricating

If you don't want to fiddle with the unit ... take it to a repair shop and tell them that you want them to clean and adjust the laser and be sure to " LUBRICATE THE GUIDE RAILS"... as a general maintance service ...

If you tell the tech that the player is skipping ... then the tech will just about automatically tell you that the laser assy/drive needs to be replaced (he makes more $$$ replacing drives then cleaning them and he's just about assured that when he replaces the drive with a new one that the skipping will go away.

Your Sony may still have plenty of life left in it ... just don't tell the tech it's skipping ... tell him you want a maintance/service just like you would take your car in for a Lube, Oil, and Filter service

HTH Dave

The laser mechanisms deteriorate with age and use so it is likely this part needs to be replaced. There is also an adjustment process that is required that typically requires some test bench equipment so it is not simply the installation of a new part. As such, it is generally not a self service item.

The last time I did this for a Denon the part was about $70. I've got a scope and other equipment so I was able to do it myself (a service manual showing the alignment procedure was another $15 or $20) but I figure most shops would want an hour or two of labor to replace, adjust and test it so it wouldn't surprise me if the repair cost ran $200 or so.

You may find it wiser to replace the unit from eBay or even use this as the opportunity to move to a PC based music server.