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Problems with MDS-JB980 QS and JVC discs?

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Minidisc boi

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Hello, i have an MDS-JB980 QS MD deck, i accidently gave it a hard knock while it was playing, and now it wont play ANY of the Crystal Gold 80 or 74 min JVC minidiscs, its really strange, all other discs play ok, well one or two sony ones dont play now either but none of the JVCs will play, other than that all other discs still play.


has any one else had strange issues with only certain brand/type of discs not playing?


it needs a service as it finds it hard to eject discs btw, no one in Australia service them any more, I am in Germany for April, perhaps I take it and maybe I can get it fixed there??



any ideas why these discs now wont play??, I confirmed with other machines the discs are fine it says (C13 READ ERROR), not disc or TOC error??


thanks people :)




UPDATE: i took the machine apart, when I put in the JVC discs they do not even attempt to spin, but all others do, the odd sony one that does not work starts to spin the stop, so it seem like it some thing to do with the actual disc caddy or some thing, either way I cant figure out what it is, Jim Hogarth have you any idea??


regards Aaron

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I have lots of these discs never found any problems with them. with any of my Sharp portables or SOny decks incl JB940 ( I do have a 980 also but is in storeage ). So very puzzling. Could be that the JVC discs are at some limit for the deck which is now upset by the knock? Where as the other discs are within tolerances. How many discs are you talking about - 10s 20s lots? I have 100+

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This is exhibiting the behaviour I have seen when a deck is one click (of the IOP value) away from perfectly adjusted.


Try really powering it off, i.e. not standby. Sounds like maybe your jolting it needs the servo to be reset. Perhaps you have artificially aged the laser. Are disks coming out warm just from playing (not a good sign)? Can you see or hear vibration from side to side when a disk is correctly playing? (you'll need the disk apart but still functional to see this).


If no luck with removing power, check the IOP value is the one written on the Optical Pickup (OP in these manuals), see page 29. With luck the actual value is written by hand in blue ink on top so you won't have to take it out and read the printed value on the bottom (or for that matter measure it according to the procedures outlined in most of the OTHER books except the later ones which have the necessity to measure the IOP value removed).


You can't do the full service without a laser power meter, so don't follow the "initial setting" part in the service manual unless you have one.


Take a look and see if there's anything in or on the optical pickup that shouldn't be. Usually cleaning will do nothing and causes more problems than it solves, unless there's so much dust around that the laser beam is seriously interfered with.


If everything is unchanged (develop a little routine for yourself with at least 2 disks, one that works and one that doesn't) try increasing IOP value (IOP write)by the smallest division it will allow you to (0.1mA). If that fails try the other direction instead. This means you remember the initial value (IOP read) by writing it down on a piece of paper ;) If you see improvement in one direction or the other try up to 3 more clicks in that direction only. But you have to decide exactly whether it's getting better or worse using the criteria i mentioned (vibration, C13 etc).


DO NOT ATTEMPT TO WRITE ANYTHING AT ALL for the moment. No track divisions, no recording, nothing. The disk you produce will simply confuse the picture. The two disks (one that works and one that doesn't) are your best hope. Once you record a disk with an out of alignment pickup you are basically screwed and have to start from scratch.


There is on some units a stray light adjustment which compensates for the difference between transparent and opaque disks (and the reflectivity of the minidisk itself) but I think on these late decks that's all automatic.


I wouldn't use it much until you have solved this - it will only get worse.


Hope this helps


Oh yes, I forgot. Before you do much else, get into the test mode (not service mode) and write down as much info as you can about any errors that happened in the past that it will tell you about. Certain things will reset this information, so you need to get it before it gets cleared. This does NOT require any disk to be inserted.

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Hello Sfbp, thanks mate and others; yes I will try what you said, btw I did do and IOP output CD and MO test and test with a TDYS-1 disc and the MO Optical system passed all tests :/ maybe its an alignment issue?

it so far has affected ALL my JVC crystal gold discs and about 3 coloured sony ones.



The JVCs wont even spin I hear the laser tring to read tho, its very strange it wont even spin the JVCs but will all the rest.


:/, I need it fixed, but there is no one left in Australia that can fix them :(



Even before I jolted it, ALL discs worked how ever they get stuck and jam on ejecting; and go back in, thats why I jolted it, to get the discs out.


no they dont come out warm, but that being said when I insert a disc some times but not all, they go in and the over write head engages but does not do any thing to the disc, the disc pushes an actuator in the mech and it pushed the head down onto the disc, so with the whole jaming issue, i thing there is an issue with the disc mech perhaps not the laser, I have also a MDS-JB940 that did the same thing, i lubed it up with PAO lubricant M-kote grease and made it worse, until i opened my 980; I noticed I put it where there was never grease in the first place.


I think the mech is not quite right now ive knocked the laser out a bit too.




I have about 8-9 of the JVC crystal gold discs NONE of them work

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Is it possible these disks were made (recorded by you) at a certain period together and that they, not the machine are actually the problem?

The fact that the tdys-1 disk works might suggest this.

Did you try changing iop by a single notch? In each direction...

It does sound as if something was up already leading to you hitting the machine.

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I have a 980 and use Victor/JVC discs all the time without issue.


As for fixing it is most likely going to be the transport that is going to be the issue. Should Jimma or someone else in Europe/North America agree to look at the unit, I believe you can just send them the transport. Much cheaper. When I tried to fix a friends 780 I just swapped the transport and it was good to go. Alas, that's the easy way. 


Shame that there isn't anyone in Australia that can fix this type of stuff. It's the same for getting old cassette decks fixed :-(

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Agreed on all counts.


I'll volunteer (as long as you pay the postage to/from Oz, not cheap), as I even have a 980 to slot it into. We can talk about settlement in kind if and only if I succeed in fixing it. Likely no parts involved.



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Now that's a difficult offer to refuse!  I, for one, can attest to Stephen's repair skills.  freddyjollo's idea makes sense as well though, maybe you could could replace it with one not as nice (or as expensive) until is is fixed, then you'll have two working decks...

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thanks all, I go to Germany tonight, soon as im home, I will have a chat and organise what we can do, Stephen that being said, I could send both mechs from a 980 and 940? or is the whole machine needed?


I got two walkmans that need repair too, for now I need the deck fixed, thanks every one :P

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Better I start with just the 980. Especially since it matches the 980 I have.


Post from Germany is not too bad. If you're going to be gone from Oz a long time, take it with you (just the mech) and send from Germany? We can sort out addresses via PM here, as long as you can login to this board.


On rereading the whole thread, punkrock (he's in Germany, you know) might be exactly right. Mechanical, if the open/close thing was the problem from the start.


If it(the error)'s really mechanical, Jim may be the best option. You could post it to Yorkshire (England!) from Germany also. He's rather slow as he has had health problems. But every time I exchange emails with him, he mentions that he's been steadily working through a pile of jobs.



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