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M1JWR

Ebay resto mds jb930

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Got a 930 coming, seller says c13 or words to that effect, so this one may be a bit more of a challenge, more when ive had a look at it, due next early week

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got that deck working, well sort of, cleaned laser and contacts etc, laser looked a bit cloudy, anyway still c13, no activity whatsoever nowt,
its working with a drive out of another 930 inside, so rest of player seems good, knock that out of the equasion.
i will have another couple of goes cleaning laser whilst drive is out.
as its sat for years things may be cloudy below the lense, i am not changing lasers as thats frought with problems.
then two possible routes of attack after that, one costs nowt and the other will cost a few quid.
the nowt one will require work and i dont know anybody thats done it before with two varients of the same type of drive unit.
i have a 520 spare drive thats laser is good, so the idea would be to change the bd boards as the 930 is type r and the 520 is not, the rest of the drive
looks identical, would need the 930's owh as the 520 one is shot, biggish job then.
the other is to wait for a 530 to come up, cheap thats is rough on the outside but works, easy peasy after that.
suppose if nobody tries it then nobody will ever know
 this deck is in near mint condition and came with the original remote, and thats a plus, they can sell for lots on their own
buy a remote get a deck free

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The 930 BD is not interchangeable with the 520 BD (and not even with the 920). I tried that, and all I got was a horrible noise from the drive (like if it was seeking very rapidly within a very narrow area)  so I shut it off immediately. Same happened with a 520 BD board in a 530.

I cannot tell for sure if this exchange caused it, but after one of these "tests" I found the 930 BD fully dead ... Therefore, I would not recommend swapping the BD boards between different families that have different DSP chips.

Apart from that, you can interchange any other parts of the MDM-5 drives back and forth. i.e., OP, OWH, switch board, motors, sled mechanism, etc.

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quite strange that, the rest ie where the op is and the mechinical parts look the same, and for all the world you would think you would be able to do that, swapping the bd's, then the cheap way would be to swap lasers, but i dont have the gear, lpm's etc, having said that, with 2 drives with interchangable parts i wont have a lot to loose will i. after that i think the 530 is the only common model that the 930 is compatable to drive wise, ofcourse there could be somthing else causing it, not ribbons this time, will look that way first before i take anything to bits

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630 has the same drive too, as well as the 730. Both are fairly rare though.

For the C13, you may want to read my silly check list here. Lots of things you can check on your own without any special gear, before you actually get to replacing/adjusting the OP (which I suspect being the cause, unless the odometers show very low usage).

Keep us posted on your progress, so we can follow, and may give you some ideas on the go.

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also i sill have the remenants of that mdm 7 drive and as far as i can remember the laser works, kms 260 b version, 520 has the a version, nowt nor summat, worth a go as in this position i dont have a lot to use, gonna test the spindle motor first by applying a small voltage to see if it spins, if it dosent then there may be a clue.

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50 minutes ago, M1JWR said:

mdm 7 drive and as far as i can remember the laser works, kms 260 b version

Now that's interesting. MDM-7 drives  normally came with the "E" version. Perhaps this one was an early unit, still assembled with the "B".

My observation is that the "B"-s are a bit more durable compared to the "E"-s. But my statistical base is "not necessarily representative" :-) .

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have done the exchange, result, player stuck in stand by, strike one, can only try the one out of the 520 now, if that fails, look for a donor box

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8 hours ago, M1JWR said:

can only try the one out of the 520 now

520 drive in a 930 is a definite no-go (see above). If you want to save those valuable parts, you don't do it.

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Had a busy day so far, had removed the ex 940 laser, cant remember the history properly, think it was iffy to start with, only played certain discs, have now put the ex now i remember 920 laser in, its original drive had a broken chassis mount  and a knackered owh, probably from transit, thats how i originally got it anyway, when i installed the 920's laser i also used its rack part and its sled pin, i also discovered that the ribbon for the 930's owh was cut through (not by me) so changed it for the ribbon off the 920's owh, that was a tricky job, the 930's spindle platter looked iffy, so also put the ex 920's spindle motor in, also as its mint and works, was tested via applying about 3.5 v to it, to cut out boring detil, have now reassembled and its working folks, havent tried record as yet but it definately plays, i dont have a iop value for this one though, the original iop on the 930 was 55.8 and on the ex 940 drive was 51.8, its set to that just now, i take it the higher the figure the more oomph it will give for recording so thats where adjustment will be needed, gradually up until it records, that if it dosent record already, if it does will leave well alone. cheers ngy for you assistance so far. parts for the bin ex930 laser, ex920 owh or whats left of it, ex 930 owh ribbon, dont know about the ex940 laser as its really unknown, did notice the switch boards are different the ex920 one is smaller than the 930 one.

can now report that it does record and writes toc and plays again after toc is written, used optical in from pc

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You're welcome.

I think it's time to lend you my first homebrew LPM (I must find it first I admit, moved home twice since then), then you could do some more sophisticated tasks with OP swapping, and enjoy more successes too.

If I can suggest one thing: not really a cost and I am sure your soldering skills are more than enough to make those two test jigs (for MDM-5 and MDM-7 type of decks that I see you mostly work with). Then you can measure IOP too as a bare minimum, and even having the laser power set "empirically" (=trial and error until it "goes"), you can get a solid feedback on whether or not the OP is still in its useable window. That can open a wholly different world for you in repairing these decks.

MDM-5:   DSC01578.jpg.868e4ec983748acd07b9a26a76a29de6.jpg   DSC01577.jpg.47953742e7cdc29bf10a41f68e4cb7c1.jpg   DSC01581.jpg.1d8bdb21ae02edafc8c4227385e07ab9.jpg   DSC01582.jpg.8524bb50a14ed8cd801038c3e2eb151b.jpg

MDM-7:   7_0452.thumb.jpg.41c5e536e5f90521ec69279126780218.jpg   7_0449.thumb.jpg.5c6f5443b22340085024266034d8fd10.jpg   7_0451.thumb.jpg.4523d482ab6d78772b3775e29834d995.jpg   7_1206.thumb.jpg.3e2793798b10c49a0076046becd892dc.jpg

 

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thanks for the pics, never thought of making a test jig, ive seen it in the service manual i downloaded, mdm 5 looks easiest, might have something knocking about from an old scrapped board for the plug end, then a piece of veroboard and some contact pins, no doubt the mdm 7 one can be done with veroboard also, if not will have a look at somewhere like farnells or rs components, apparently the iop is written on a sticker on the laser on the mdm 5's, the sticker is there but no writing, drat !! I cant be far away or it probably wouldent work very well or at all, ive put that deck in a box just now, suppose getting it working is a good start, had a quick look at that 520 that i have thats complete from a while ago and its iop is 54.1, i realise that it dosent really tell me anything , just probably its unique for that perticular machine, i tend to stick with the simple mdm shot belt issues, but of course the odd one turns up with a bit extra, like the 440 with a bd board swap and the 940 that started it all for me when we stumbled on the ribbon cable partial cure for some faults, it also had a fault with one of the optical inputs as it was getting no power, an invisable hairline through a track was the fault, so i jumped it with a wire link, all good education.

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8 hours ago, M1JWR said:

its iop is 54.1, i realise that it dosent really tell me anything , just probably its unique for that perticular machine,

Here is the thing: (I am sure you will get to the "aha"! :-) )

- the IOP value printed in the OP sticker is the nominal IOP value of that OP,  defined during the production of the OP, for the nominal laser light emission power (for recording mode), giving a note to assemblers, how to set that very OP later in a deck/drive.

- the IOP value hand written on the OP or on the drive frame (i.e., like on the MDM-3 drives), is the IOP value the factory measured when that OP went into a drive during production of the deck (should that be Sony, Sharp, Onkyo, JVC, etc., that share the same type of OP). This second one can be slightly different from the first one, either because of some other settings for that model/make, or simply because the factory measured slightly different laser emission during building the drive/deck.

- the IOP values digitally recorded inside the Service Menu is (should be, normally) the exact copy of the former two, for given purposes (mainly for service personnel, when a future repair is necessary, so they would not have to open and disassemble the machine to get this information. After an OP replacement, the measured IOP of the new OP should again be written back to the NV memory, for the same purpose.) Later models (MDM-7 flavours) have an additional feature, namely those drives can compare the IOP value input by a "human" with the value they measure themselves, and report back to the "human" whether the laser is "OK" or "NG" (good/not good).

But all three should tell you the same: if the OP emits its laser light with the required intensity (=laser power) at this electrical IOP value (=in a +/- tolerance range around it), then the laser diode is working properly. This piece of information is invaluable when hunting for C13 or similar errors. For example: if the measured IOP value is way off of this range, you will immediately know, that the laser diode is already gone (and saves your time swapping - potentially bad - OP-s in the hope that will help getting out of a C13 or stuck in standby).

I see your point on which kind of repairs you tend to deal with, it is just a potential addition to that cool feelings when something comes to live and begins working again :-) .

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there is also this, i for fun checked the 930 with correct matched drive unit inside in service menu, c27 55.1/54.3 on iop read, and the actual iop value on that deck is 54.3, so with two figures there, would that mean a possible error of correction sort of thing and a figure between those two would be ok, plus in the mix drive 930 as we will call it, again there are two figures originally 56.4/55.8(currently set to 51.8 instead of 55.8 as that was the setting for the laser out of that 940 drive that i tried first), i think i am starting to get it now, will leave that one in the box until i build a test rig, will see how i get on through the week.

thought kevin would have had a word or two by now, its deep stuff !!!

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6 hours ago, M1JWR said:

with two figures there, would that mean a possible error of correction sort of thing

First number is the nominal IOP value (as on the sticker), second number is the IOP value measured at the time of installation of the new OP (with or without a handwritten note on the OP/drive). The difference shows whether or not the laser diode works in the required range.

Again, please note, these IOP "settings" in the service menu are not "Settings", these are simply notes in digital form, for human information only. In other words: as the IOP value on the sticker obviously "does not do anything" to the OP/drive electronically, nor do these values in the service menu either.

Ultimately, you can write ANY numbers there, it will NOT impact the behaviour of the laser AT ALL. I know it may sound weird, but this is the case.

What is important, that the IOP must be measured, in order to get the information on the laser diode status (="health").

The reason I keep repeating this as a broken record is that by simply (="blindly") swapping an OP and copy the IOP values from the service menu of one drive to the other  is not going to "repair" anything. Yes, if by chance (=status of the lasers unknown) you replace a "dead" OP with a still working one, your drive might come alive ("might", for the numerous other checks [see more on that here] required for setting up a laser in an - other - drive). Better do this "consciously", with the necessary information in hand. Otherwise then, if the swapped  laser was "good", it can just quickly die (and take other parts with itself too), also, an already "bad" laser can just kill other stuff in that drive too, or at least render (leave) the deck faulty, and the (new) reason would not be known.

When I have to work on a deck for any kind of repair, the first thing (well, amongst a few "trivial" stuff obviously) I do is I pop in the LPM, connect the test jig, and measure the laser power and the respective IOP values. This will show if the OP is worth to deal with or not, also, if the OP can be a culprit of an error or not (necessarily).

All I am trying to say here is stated in the service manuals way more precisely than I can ever phrase. Deep stuff I admit, that's why I thought some "plain" explanation might be some help for those for whom an SM seems "written in Chinese". But I keep my mouth shut up then :-) .

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I can’t add to perfection! :-D

The only thing I can reiterate is ESD precautions for both the laser and PCBs.  When handling an unmourned OP it is paramount that the ESD link on the laser is bridged and removed in accordance with the Service Manual. Also when replacing such, the SM does detail the procedure and subsequent calibration. Test equipment in absentia, NGY has documented the pragmatic steps. 

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9 hours ago, NGY said:

All I am trying to say here is stated in the service manuals way more precisely than I can ever phrase. Deep stuff I admit, that's why I thought some "plain" explanation might be some help for those for whom an SM seems "written in Chinese". But I keep my mouth shut up then :-) .

I always regarded the SMs as if they might well be written in Hungarian. No offence to your native tongue (which does have a reputation of sorts you will admit). Maybe that's why you and your countrymen are good at fixing electronics (Elektrotanya.com is from there).

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thing is i am more mechanical minded than electronic minded. some things i understand and some i dont, so yes some parts of the sm is in chinese to me, ngy has cleared up a lot of things here for me, ive had nothing to do with installing minidisc lasers before, its all a learning curve to me, thought i did quite well actually getting it working, i was expecting it not to, i live in cumbria, us cumbrians will get the for example lawnmower off the side of the road that the guy has chucked out because it maybe has dirt in the fuel or something, sort it out and get 10 years out of it until its a wreck, at that time the cumbrian will look for another, the same or similar, make something out of the two and try for another 10 years, just the way we are, just as ngy says i have 2 not totally compatable units and got something working and it gives you the "good feeling", i realise its not over yet until i make up a jig, then hopefully we may have something a bit more concrete to go on.

 

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I like your approach of trying to fix things that already been tossed away by others, if still can have useable lives after being repaired. I have a similar mindset since I was a kid. My first touring bicycle was pulled from a junk yard behind a Parisien bicycle sports club. It took me a year to gather the missing or broken parts, repair, repaint and re-assemble. I was then the "cool boy" in the school with that sports cycle (it had a Peugeot frame and alu rims I remember), to what not even the famous Czech Favorite came close that time. When grown up I gave it to a relative as a gift who rode it as well for many years. I wish I still had it today, it would be worth a "pretty penny" I guess :-) .

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yep, had a kawasaki z1000j motorcycle for years, one time the rear brake master cilinder went fubar(old age) good used ones were onobtainable, and new ones that were still available at that time the prices were unbelievable, so off to the breakers yard to find something similar, got one for a gpx750, fitted it and bled it etc and it worked spot on for the rest of the years i had the bike, it the case of the md drive, i suppose i fixed it "mechanically", but not yet electronically so to speak, wish i still had the z1000j they are worth lots now. its a case of not a lot to loose and everything to gain.

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