[Jdpurvis]

As the title says, I'm battling with a CD player (Sony CDP-N550C) that's randomly skipping. I already replaced all the buttons in the entire system (before I got the complaint about skipping, the system was basically unusable at that point). While investigating the skipping I found the plastic pickup guide (it only has one metal rail) was broken in several places, so I fabricated a new guide out of metal. The guide is completely flat, the same height and it's been lubricated. I even tried a new pickup, but it still skips. Sometimes it'll skip a couple seconds, other times it'll skip to the end of the next song, or even several songs at a time. The skipping is also completely random, and it doesn't matter what CDs are used.

Can any of you think of another reason why it would do this? My aunt doesn't want to move away from physical CDs, and she doesn't have the money to buy a new changer.

I don't have a good suggestion for fixing this drive - It could be dirt on the lens, or some intermittent electrical problem. You could spend lots of hours trying to fix this, and still wind up stuck. I would look around for a good used player - shouldn't be very expensive these days.

 

[JKuhn]

The lens shouldn't be an issue, I tried a brand new pickup (and cleaned both). It also finds any track immediately, so it doesn't have the usual symptoms of tracking issues.

To be honest, I've already spent many hours on this system (just the buttons were a lot of time, since I did the amp, radio, tape deck and CD player). At this point I'm thinking a bad main board, but I'm trying to get more opinions before I give a final verdict. We're also a bit cautious about a used player, since it's not like an amp (or speakers) where you can simply test it a bit and know if it's good or bad. I've noticed a bad pickup can cause intermittent issues. And a new changer is around R7-9k. Which my aunt said she couldn't afford.

 

[Darren9]

I don't think it'll be the optical system, seems more like logic/control, the seek function can seek some amount of seconds forward and some amount of tracks forward, my guess is it's generating random seeks in both seconds and whole tracks (random seek forward in seconds alone would almost never coincide with a track start).

I haven't used that particular player, is it a multifunction forward seek (press once to skip a track, press and hold to skip seconds or something similar)? Isolating and testing the signal integrity for that particular function though seems very problematic. Probably a new main board if it contains the logic/control section.

It could possibly still be a button issue, especially if you have one button that forward seeks tracks and seconds depending how long it's pressed.

 

[kiriakos]

Can any of you think of another reason why it would do this? My aunt doesn't want to move away from physical CDs, and she doesn't have the money to buy a new changer.

You started troubleshooting from the wrong direction.
How about confirming in specs operation of DC voltage lines for the CD rom?
The problem this is electrical and no mechanical.

 

[JKuhn]

I don't think it'll be the optical system, seems more like logic/control, the seek function can seek some amount of seconds forward and some amount of tracks forward, my guess is it's generating random seeks in both seconds and whole tracks (random seek forward in seconds alone would almost never coincide with a track start).

I haven't used that particular player, is it a multifunction forward seek (press once to skip a track, press and hold to skip seconds or something similar)? Isolating and testing the signal integrity for that particular function though seems very problematic. Probably a new main board if it contains the logic/control section.

It could possibly still be a button issue, especially if you have one button that forward seeks tracks and seconds depending how long it's pressed.

It's not skipping to the start of a track. It's skipping to some random spot in another track, I've seen it happen a few times now that just after starting a new track it jumps to just before the end of the next one (sometimes even skipping several tracks at a time).

You started troubleshooting from the wrong direction.
How about confirming in specs operation of DC voltage lines for the CD rom?
The problem this is electrical and no mechanical.

When I started looking into the skipping, I also thought electric/electronic. Then I saw the broken guide, which could cause the pickup to jump around, so I started by fabricating a new guide (after trying to source a new pickup/drive unit).

 

[oobymach]

Your replacement isn't made of the same material so my guess is it's adding too much friction (maybe it's bigger/wider than the original) and the laser tugs regardless of whether or not it's got enough lube (I use white lithium grease on cd/dvd/bluray drives).

If it's just the one on the guide and not the one on the spiral track you need teflon or ptfe between the metals preferably on the new part, you can rob an old mouse of its foot if you need to most mouse feet are ptfe. The addition of a low friction material should help the skipping.

 

[JKuhn]

Fair point. I'm not sure how that will be done though, considering adding something on top will just make it too thick.

The base unit plate has the gears on one end, with a regular rail holding the pickup on that side. On the other side it had a plastic guide molded around the plate, and that plastic broke in several spots, making it uneven. So my fix there was to add a piece of galv plate (same thickness), with an epoxy stopper on one end (the original guide also had a stopper), and then I lubricated it with silicone spray lube (all I could get without risking the presence of paraffin). The metal guide is wider, but considering the design that won't matter. This is what the original guide looked like.

 

[Asmodian]

I bet the new guide isn't quite right in some way. Any jerk or slight catch would easily cause it to skip to a new track.

Of course, the root cause could be anything, but I wouldn't give up on the mechanism yet. It is so finicky and just barely working at the best of times that anything different can cause major issues. The way that lens locks onto the spiral means any roughness on that surface could be significant.

I wonder if the extra metal is messing with the electromagnetic fine position control of the lens? Smoothness issues seem more likely but that thing is as cheap as possible while still working and I don't know how sensitive that electromagnetic control is. Why wouldn't they use the edge of that frame instead of the plastic rail if they could? It looks like it has a plastic spring component too (those bent arms holding the rail in place). Maybe it needs to push slightly to keep it steady, but not too much, and be very smooth? It seems tricky to fabricate a good replacement out of galv plate.

 

[UltraMega]

Out of curiosity why even go through all the trouble? Surely you could get another CD player for cheap these days.

 

[JKuhn]

I bet the new guide isn't quite right in some way. Any jerk or slight catch would easily cause it to skip to a new track.

Of course, the root cause could be anything, but I wouldn't give up on the mechanism yet. It is so finicky and just barely working at the best of times that anything different can cause major issues. The way that lens locks onto the spiral means any roughness on that surface could be significant.

I wonder if the extra metal is messing with the electromagnetic fine position control of the lens? Smoothness issues seem more likely but that thing is as cheap as possible while still working and I don't know how sensitive that electromagnetic control is. Why wouldn't they use the edge of that frame instead of the plastic rail if they could? It looks like it has a plastic spring component too (those bent arms holding the rail in place). Maybe it needs to push slightly to keep it steady, but not too much, and be very smooth? It seems tricky to fabricate a good replacement out of galv plate.

I see what you're saying. Maybe I should clean the guide, polish it and lube it again. Those spring-looking plastic pieces are just lines where the plastic flowed during manufacturing, apart from the tab that holds the metal rail/pin in place.

Out of curiosity why even go through all the trouble? Surely you could get another CD player for cheap these days.

My aunt doesn't want to move away from physical CDs, and says she doesn't have the money to buy a new changer (from what I've seen they're around R7-9k nowadays). And we're both hesitant to buy a used one, due to the risk of motor/pickup/button failure (which are often intermittent, and therefore hard to test before buying).

 

[UltraMega]

I see what you're saying. Maybe I should clean the guide, polish it and lube it again. Those spring-looking plastic pieces are just lines where the plastic flowed during manufacturing, apart from the tab that holds the metal rail/pin in place.

My aunt doesn't want to move away from physical CDs, and says she doesn't have the money to buy a new changer (from what I've seen they're around R7-9k nowadays). And we're both hesitant to buy a used one, due to the risk of motor/pickup/button failure (which are often intermittent, and therefore hard to test before buying).

If you bought one on eBay and it didn't work, you could send it back. If you found one in a thrift store, it would probably be dirt cheap.

 

[kiriakos]

My aunt doesn't want to move away from physical CDs,

Neither do I, as I have very high quality sound system and several GENUINE CDs.
Now stop playing the doctor, and give the unit for repair to a REAL Doctor.

 

[Asmodian]

Those spring-looking plastic pieces are just lines where the plastic flowed during manufacturing, apart from the tab that holds the metal rail/pin in place.

These are the "springs" I was talking about:

 

[JKuhn]

Neither do I, as I have very high quality sound system and several GENUINE CDs.
Now stop playing the doctor, and give the unit for repair to a REAL Doctor.

Those places nowadays refuse to work on old stuff. They just say to throw it in front of the next truck (without even looking at it).

These are the "springs" I was talking about:
View attachment 2514659

Those aren't springs. They're just channels in the mold for plastic to flow through, and maybe also to stabilize the standoffs. The original guide was held solidly in place as it was molded around (and through) holes in the plate. And the two large ends of those "springs" are standoffs on the other side.

 

[Asmodian]

Those aren't springs. They're just channels in the mold for plastic to flow through, and maybe also to stabilize the standoffs. The original guide was held solidly in place as it was molded around (and through) holes in the plate. And the two large ends of those "springs" are standoffs on the other side.

Ah, interesting. Those really look like flex members they often use, but you definitely had a better look at it.

 

[kiriakos]

Those places nowadays refuse to work on old stuff. They just say to throw it in front of the next truck (without even looking at it).

I do not buy that.

Final advice: Contact SONY so to get a list of authorized repair center at radius of 150Km from your location.