SONY D-250 middle gear lubrication/replacement

I recently bought a cheap SONY D-250 Discman on an auction site, which was described as faulty laser.
Given @Jorge told me about the common problem with frozen middle gear, I hoped this was the only problem and not the laser itself. Seems I was lucky in that regard and everything is in perfect working order apart from that frozen gear. Have to say the unit sounds very good, clearly one of the best Discmans ever made.

There's nothing else I have done, except for a general cleaning. Given how good it now plays CDs, I didn't even bother to check the PLL free fun frequency, tracking balance and focus bias.
I will probably do that at some point in the future, but now I'm more concerned with building a custom 3D printed battery case for it, as it seems that there are no plug-and-play replacements available at this point. Will make a separate thread regarding the battery when it's finished.

Now, getting to the point. Disassembling the unit is pretty straight-forward: You need to remove all the marked screws (3 on the side). All of them are the same length, so no problem with mixing them.
Then the small board with the DC input and LINE OUT jack must come out together with the battery tray.

NOTE: There is a metal spring that keeps the sled in place, which does not appear in my pictures. That also has to come out, it's latched onto a plastic catch and it can be easily taken out.

 

Hi Valentin. Very nicely explained. Unfortunately I don't have the 250 but the dz555. Have you stripped down a 555? My 555( serial no- 33,538) I think needs the three 100uf 6v capacitors replacing. Although the left/right balance is fine I think the volume is on the low side. My d-350 blows it away in that regard. Are the capacitors surface mount or through hole? Sorry about getting your name wrong the last time, Derek.

 

No, I did not repair any 555. But @Jorge certainly has, so he can answer your questions. Creating a separate thread regarding that question is not a bad idea either, as it's clearly not related to the middle gear.

 

Glad you could make it work @Valentin ... a bit SAD it was me who pushed you onto the Dark Side of Digital
D-250 was my first 'hi-end' Discman also, revived for me by verhayen.com about ten years ago (guy even had custom-printed mailing boxes for shipping D-250 back to the customers!!!). For when I had thousands (low tens-of thou?) CDs in my collection Discmans were my main headphone-listening front-end (for when The Boss wanted some silence from my main Stereo!... that is My excuse for falling in love with them Discmans

Upon request I will post a separate revival how-to for D-Z555... to fix D-Z555 is so easy that it's almost boring...

A few extra points on the OP of this infamous "middle gear":

About 5-7 years ago when I fell in love with Discmans all I had to do to fix the 'middle gear' problem was as described by @Valentin! Nowadays middle gears in D-90, D-99, D-88, D-555 have 50:50 chances of being totally ruined by bad lubricant used by Sony. Brass pin-lubricant-plastics chemistry at work, see for yourself:


Plastic gets orange, then green, then crumbles, the one on top was ruined by a previous repair attempt when the Dude scraped it when trying to break it loose...

So... when you see 'middle gear' going green, buy a new one off eBay! I have a few gears 3D printed (my son designed AutoCad model for ShapeWays, $7 each) but I also made a cast from the Real Thing and the ones I have from the mold I like a bit better - unlike 3D prints they are smooth and a bit softer.


Lubrication: @Valentin you forgot to mention which lubricant you did use for this infamous brass-plastics! We do know that it was the original Sony lubricant which got stiff and then destroyed the middle gear.
The one I used for a few years is in the middle:


but now we know that it gets us into the same troubles as the original Sony oil, so for a few years I did not use any lubricants for brass-plastics at all. The one at right from Nalgene (highly respectable Co in my professional field) is what I am using nowadays, have no idea if it is any good, only time can tell

Next headache: gear at the sled motor! they are starting to split! All of them split/broke at D-10/D-100 that I managed to fix so far, and now they are doing the same on D-90/99/555!!!

 

I'm glad to be on the Dark Side of the Digital, @Jorge ! Portable CD players like these are not made anymore... I'm impressed how good this player sounds, it clearly exceeded my expectations.

Interesting story about how you felt in love with Discmans, @Jorge !
My primary motivation for getting into this hobby was I never got a Discman in the 90s when I was little. Although, from what I remember, here in Romania CDs became very popular at the end of 90s and into the 2000s. And they quickly disappeared after that.
My first audio CD was "Mike Oldfield - The Songs of Distant Earth", which I listened to on my PC. I remember those old optical drives which had a volume pot and a jack for plugging headphones.
In the 2000s I got a SONY MHC-BX2 mini Hi-Fi component system, which was much better for both audio tapes and CDs, but far from really being Hi-Fi. I've got one or two boomboxes after that and then came a pause.
In the meantime, I made the mistake of throwing away many CDs and tapes, thinking I will not need them anymore thanks to YouTube and streaming. Of course, that proved not to be the case and I got into re-buying some albums that can only be found on physical formats.
The real involvement in this vintage audio hobby began about 5 years ago when I got my first deck: the Technics RS-BX606. I was unfamiliar with Dolby at that point and became really impressed with how Dolby C can tranform a tape.
In parallel with all these is the fact that all my life I was into electronics, whether it was designing circuits or repairing them. This combined with the love for vintage audio made me want to repair a lot of these old gems.

Back to the point, guess I was lucky not to have a completely green middle gear. Fortunately there are new gears available, so it's not the end of the world if it breaks.

Lubrication:
Now that I read back, I realise I did indeed not say which lubricant I used. My opinion is most of the lubricants available today are much better than what was available back in the day.
Given how much car engine oils have evolved over the last decades, I believe all lubricants have evolved and are much more compatible with different types of metals and plastics.

So given what I stated above, I think what @Jorge recommended are all very good options. Leaving it dry is also an option, but in this case cleaning everything 100% is extremely important (this is probably the safest option if you're concerned with chemical reaction between grease/oil and plastic).
My personal preference is to use oil wherever I find a situation like these where part of a mechanism gets stuck from old grease; this preference comes from an oil being much thinner than grease and also does not tend to get hard over the years.
Of course, the type of oil is also important, as not all oils will keep their properties in equal amounts. I used Moebius 9010 watch oil in this particular application, it is compatible with both plastics and brass (as stated in the datasheet).
However, I must stress that this is how I prefer to do it and not necessarily the best way to do it.

Sled:
Something else I did not mention because have forgot to take pictures with the process is this: I also re-lubricated the plastic bearings on which the sled rotates. Cleaned the grease and put watch oil instead. This was likely not necessary, it's just something I prefer doing.
I might also re-lubricate the sled itself at some point in the future: I will use white lithium grease there, as it needs to stay of the shaft and oil will not stick, but rather fly everywhere (also on the CD) when the sled rotates.

 

I recently got a D-250 with the stuck gear issue. I was able to clean it but noticed it started cumbling. It works for now but I'm worried that it might break soon.

Looking for replacement gears I found several 3D printed offers but quite expensive (5-7€ for one gear). So I decided to get them printed by a service (pcbway) instead. The problem is they came out slightly warped (which the service warned me could happen but I still wanted to try it). I'm not confident to put them in my valued D-250 and I'm sceptical other sellers of this gear in 3D printed resin will be better.

Has anyone got a source for a good replacement gear? Maybe casting it myself from the still intact original is the best option after all? But casting such a tiny gear is probably difficult too.

 

I don't think 3D printing is a good option for gears, at least not at this point in time.
Problem with 3D print is it just cannot be as strong as an injection molded part, even if the resolution is good enough to reproduce the teeth.

I would only consider injection molded ones, despite they're more expensive:
https://www.ebay.com/itm/314769673955 (this one is from Germany)
https://www.ebay.com/itm/314478281138 (this one is from China)

Compared to the value of the Discman, I think $15 is a very reasonable amount to do a proper fix.

 

Those are also 3d printed. The german one clearly says so in the listing, the chinese one can be told by looking at the pictures. The ones I ordered even have the same color as the chinese listing.

 

Ok, my mistake I lived with the impression those are injection molded, but didn't pay careful attention.
So there's nobody making an injection molded replacement for this gear ? All are 3D printed ?
If this is the case, it's better to keep the original one intact.

 

I haven't found one yet and I doubt it exists. Injection molding is expensive, the tool alone costs several thousand € / $

 

I purchased several different middle gear's from 3 different vendors / makers. Including the German guy on e-bay. His is the one I put in the D-555. Honestly, all 3 gears from different sources, look the same, slightly different colours though. I put the Labelle 106 PTFE grease on the carefully cleaned brass pin and 3D printed gear. How long will it last? I've only got about 15 hours on the 555 so far. I'll just replace it with another if it crumbles. Thus the need to keep a lot of spares around in case the few sources on e-bay stop selling them.

EDIT: In a later model year D-90 with low hours, that I got for the KSS-220 laser and sled assembly spares, the middle gear was solid and in good shape. So I have original gear just in case. It's a good idea to buy up compatible models for spare parts too.

 

Hola!!!
I have cleaned plastic gear, (there wasn't much grass). It finds its tracks when I change a track to the next one - it goes (the move of the gear is not gently, it stops and go, but it goes)., but
When I want to play to the previous track or any of the earlier ones - the laser motor doesn't rotare. laser head doesn't move. If i move the laser head manually to the start location it goes again, but it cant back down.
Any advise please? What can i do?

kind regards, Tom

 

I had these symptoms on my D90 (albeit I still need to clean the laser) before I made sure the middle gear was loose enough. Could be the metal rod it sits on has corrosion on it and needs to be cleaned off. Make sure you add some lithium white grease to the inside of the gear and put it back on.