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Sony MDS-JB 940 Static Mini Disc Player (fault)

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fourbanks

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Hi friends 

I have just noticed on my new Sony MDS-JB 940 Static Mini Disc Player that on inserting the disk it says reading TOC and plays well . however on ejecting the disc it says eject then goes straight to the message reading TOC without ejecting 

The unit has only been used once before storage many years ago. hopefully i will be able to fix it as our good friend Jim is no longer here ?

 

Edited by fourbanks
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Dead easy. Just make sure you don't leave the belt twisted if it ends up that way after you first put it on.

If I recall correctly, this is roughly the sequence

1. Remove lid.

(EDIT) If there is any disk in the unit, persuade it very gently to come out, using whatever tools you have to do the work of the belt that's not working (i.e. push the eject button and "help" it to eject). Probably easiest with the power on. (EDIT)

2. disconnect ribbon cables making sure you know where they go back (it should be obvious) leading to the mainboard from the MD unit. ONLY DISCONNECT ONE END OF EACH.

3. Undo the grounding straps (they are push fit), I think there are only 2 you care about, making sure you know where they came from.

4. Remove/loosen the front panel (6 screws or so), only enough to remove the MD unit. See the service manual. If you're smart you won't completely undo it.

5. Undo the 4 "flying saucer" screws anchoring the MD unit into its rubber bushings.

6. Now you can take the MD unit into your hand with no wires or anything. Prise the plastic mechanism by squeezing just enough to let it open past the (plastic) stop and open the main hinge very very carefully making sure not to bend or stretch anything particularly the overwrite head. You should be able to replace the belt now.

Putting it back together is easy. The service manual shows it all (the DISassembly of course). Nota bene: you should not have to disassemble the MD unit itself. Particularly if you get to something that says "remove solder" stop immediately and reconsider your fate.

Good luck

Stephen

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  • 5 weeks later...

well well well. I thought I would check my store of mindisck decks jb940 and one also  now shows the same problem! Does time  deteriorate the belt esp when not in use or maybe the storeage conditions?  This is the first time this has happened to me. is it common? as it was fine when stored away and never gave any trouble of any kind. By the way where is the service manual referred to above as it seems I will have to do the same job!!

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well I started to dismantle mine. it is nt necessary to undo the front at all as once the  saucer screws are undone it lifts out clean. re the grounding straps - cant see any. Now just got to get to the belt,  the instructions above a bit un clear. I can see the little  belt from the front? only one belt? What should I expect to see? a broken belt? Mine is still intact and in place.Just slipping then? and a new one will do the job?

Edited by freddyjollo
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well I started to dismantle mine. it is nt necessary to undo the front at all as once the  saucer screws are undone it lifts out clean. re the grounding straps - cant see any. Now just got to get to the belt,  the instructions above a bit un clear. I can see the little  belt from the front? only one belt? What should I expect to see? a broken belt? Mine is still intact and in place.Just slipping then? and a new one will do the job?

Mine is still intact and in place.Just slipping then? and a new one will do the job?

hopefully freddy that is all it will be ?

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to open the "main hinge" I think you have to remove a small spring at the side that otherwise keeps it closed. This is a very small spring with not too much tension that I think could easily be damaged so do with care. I havent got to that state yet, as I am waiting for a spare belt to arrive.

i will follow your lead we can do this together when your new belt arrives 

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to open the "main hinge" I think you have to remove a small spring at the side that otherwise keeps it closed. This is a very small spring with not too much tension that I think could easily be damaged so do with care. I havent got to that state yet, as I am waiting for a spare belt to arrive.

The spring is no big deal, but you may want to remove it early just to make sure it doesn't get bent out of shape (it's easy enough to bend back). The belt, on the other hand can slip quite easily and no amount of adjusting springs etc. will make any difference to the mechanism functioning properly.

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A lot of the decks around that time use the same mechanism. However there are different cable widths (17,19,21,23 pins on the principal cable from MD to mainboard). So one must check AT LEAST that the 2 cables have the same number of pins. It has to do with the extra control lines related to M-Crew/NetMD support (remote), IIRC.

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i'm afraid this did not go well as the piece of the laser broke off so if possible will need to put the rest of this unit into a old 920 uk model like the lighting unit ? and the belt i have just brought  ?

i have a tv electronic engineer who works close by so he may be able to swap some of the parts over ?

 

 

Edited by fourbanks
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Can you take a picture?

i have dropped the units over at the at the engineers so i'll leave it up to him as the best way forward. the laser unit of the old 920 did work but has been heavily used. He might just swap that over but failing that he will if able just swap the main light unit over as it's new and will just keep all parts for a later date 

these things happen and if i came across the same model will get another this was just bad luck

will keep you posted  

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Unlikely. The 920 doesn't support MDLP, but the 940 display has all kinds of stuff to do with that hardwired into the display.

is the SONY MDS-JB930 QS a step up to the JB 920QS or the equivalent to the 940 ? do you know 

Also Sony MDS-JB730 QS Black High-End Minidisc Deck what is this machine like ? 

http://www.ebay.co.uk/itm/Sony-MDS-JB730-QS-Black-High-End-Minidisc-Deck-MINT-Condition-/181882628629?hash=item2a590caa15:g:wjcAAOSw9r1WBTVI

Edited by fourbanks
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None of the x30 decks support MDLP.

http://minidisc.org/part_Sony_MDS-JB730.htmli will have some spares for a later date if needed ?

 

I have decided to get another JB940 so that i will have the spare parts for the future as it is a good deck overall and will keep the belt in case it's needed at some point

As for me fitting it then no i will pass on that as my dealer says he's more then capable  

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its a shame no one here can give  definative info  regarding which decks use the same transports then you might have been able to buy a cheaper deck and transplant the mechanism, which was my question above. Certainly this  rubber band  issue makes you wonder how long these  decks will last as the assumption was that left unused they would be ok? now we know that there was a countdown from new? just because of a silly little  rubber band!

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It's all in the service manuals, Freddy. They've been posted at minidisc.org for years now. There are plenty of cog wheels already in the mechanisms - I think the rubber belts were/are a good engineering solution. All CD players and DVD drives use them in some form or other.

As to which drives can be transplanted, of course one can make a list. But all that is required is a $5 belt.

Nick, did you omit to remove the disk before disassembly? I'm sorry, I omitted that from my instructions.

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It's all in the service manuals, Freddy. They've been posted at minidisc.org for years now. There are plenty of cog wheels already in the mechanisms - I think the rubber belts were/are a good engineering solution. All CD players and DVD drives use them in some form or other.

As to which drives can be transplanted, of course one can make a list. But all that is required is a $5 belt.

Nick, did you omit to remove the disk before disassembly? I'm sorry, I omitted that from my instructions.

i did not Stephan which was a bad error on my part as at the time it would not come out where as before he had albeit hit and mis 

as i say i hope to get hold of a newish 940 and i will now have some spare parts if needed i will let you know when i get hold of the new one although it may take some time 

is this model any good do you know

http://www.ebay.co.uk/itm/Sony-MDS-JB730-QS-Black-High-End-Minidisc-Deck-MINT-Condition-/181882628629?hash=item2a590caa15:g:wjcAAOSw9r1WBTVI

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I got a JB940 earlier this year, which on occasion exhibited this problem of not ejecting the disc. Usually it would work fine, but if it had been turned off for a while with a disc inside, after turning it on the eject mechanism would make a slipping sound and the disc wouldn't come out until after several tries. I guess the slightly lower temperature inside when it had been turned off for a while had something to do with it.

I replaced the belt just now. I was a bit hesitant to do it, because the deck would mostly function fine, but It is indeed dead simple. After removing the mechanism, the belt is easily accessible from the front and can be replaced with a little help from a highly specialized tool.

P.s.: I just noticed I took the picture of the mechanism after I had already removed the belt. It goes around the two white wheels you can see on the front left.

JB940-1b.jpg

JB940-2b.jpg

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its a shame no one here can give  definative info  regarding which decks use the same transports then you might have been able to buy a cheaper deck and transplant the mechanism, which was my question above. Certainly this  rubber band  issue makes you wonder how long these  decks will last as the assumption was that left unused they would be ok? now we know that there was a countdown from new? just because of a silly little  rubber band!

i have a very rare cd recorder from marantz that skips for the first 5 minutes of playing but woks perfectly after that so i'm leaving alone just to be on the safe side 

http://www.hifiengine.com/files/images/MARANTZ DR6000 CD RECORDER PLAYER.jpg

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It's all in the service manuals, Freddy. They've been posted at minidisc.org for years now. There are plenty of cog wheels already in the mechanisms - I think the rubber belts were/are a good engineering solution. All CD players and DVD drives use them in some form or other.

As to which drives can be transplanted, of course one can make a list. But all that is required is a $5 belt.

Nick, did you omit to remote the disk before disassembly? I'm sorry, I omitted that from my instructions.

I wonder  how long the the rubber bands will be available for? That website mentioned only had 65 left ( I bought 5 just in case ) then what?

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