MDS-JB980 C13 Read Error (SOLVED)

[BearBoy]

Turned on my MDS-JB980 this morning. Screen displays the title of the MiniDisc I had left in the deck overnight. I press play and the name of the first track appears but I can just hear the disc spinning and no audio. After about 10 seconds of this I eject and re-insert the disc at which point I get TOC Reading followed by C13 Read Error. Tried the disc a couple of times with the same results. Try a number of other discs and the same thing happens. The discs all work fine in another deck.

I'll disconnect the deck and take the lid off this evening to try cleaning the lens with some isopropyl alcohol but in the meantime I thought I'd try a lens cleaning disc. This worked fine. The deck recognised the disc without any issues and it played fine. Unfortunately it does not appear to have had effect on the deck's ability to play any other discs.

I'm guessing that the lens cleaning disc is a pre-recorded/pressed disc. Is there any reason why the deck would recognise and play this without any issues but not play any home recorded discs? Something to do with the required laser power or something?

[kgallen]

Interesting...

(Sorry if you already know this) Pressed discs use "pits and lands" the same way as a CD. These discs are "high reflectivity" regarding the detection mechanism used to extract the data. Recordable MO discs use the Kerr effect of rotation of the (laser) light polarisation due to magnetic field and are "low reflectivity" in the detection mechanism. The reflectivity type is coded with a dimple on the disc case, but also in the lead-in data that the machine gets when it first reads the disc. This lead-in data is put there when the disc is manufactured (CD and MO type) and is not changeable on MO discs (it is in pits and lands format, but "low reflectivity" - see Primer page 34).

I'm not aware the read laser emit power is different for each of the disc types, but I could be wrong, I'd have to re-read the MD technical primer [*] on minidisc.org to refresh my understanding. ETA looks like both CD and MO discs use the same laser read power (~0.5mW, Primer $6.3 p40). So it's interesting you see a difference between your MO and (possible) CD "cleaning" disc. Have you any other CD discs you can try?

According to the Primer doc, p39, the same detector elements (I and J) are used for detecting both pit and MO signals, so it wouldn't seem there is a fault with the detection optics/electronics. (But as ever we should look at simple explanations first, rather than some catastrophic component failure on an otherwise known-good machine!)

However I'm not sure what these "lens cleaning" discs look like. You say it's a playable disc, rather than one with "some fluffy stuff" on it!

Whilst you have the lid off, try the ribbon cable remove-and-reseat that seems to have recovered some of our machines from C13!

Good to hear from you now SIF is back online!

Kevin

[*] http://minidisc.org/manuals/minidisc_training.pdf

[BearBoy]

21 minutes ago, kgallen said:

However I'm not sure what these "lens cleaning" discs look like. You say it's a playable disc, rather than one with "some fluffy stuff" on it!

Here's a photograph of this particular one. Not sure how easy it is to see from the photograph but the bottom of the disc is almost completely exposed and it has a small white fluffy brush attached to it. The disc has three tracks on it that play some classical music whilst a lady reads some instructions and then confirms that the cleaning has completed.

[BearBoy]

21 hours ago, kgallen said:

Whilst you have the lid off, try the ribbon cable remove-and-reseat that seems to have recovered some of our machines from C13!

Good to hear from you now SIF is back online!

Kevin

I had been reading your thread about the C13 errors on your MDS-JE530 and how the ribbon cables were the culprit. Was going to reseat them whilst I had the lid off but was just a bit confused as to why my deck could read the cleaning disc without any issues.

Good to see you've found your way back too Kevin!

Edited May 7, 2020 by kgallen
Cheeky insert link to Forum topic on MDS-JE530 C13

[kgallen]

That cleaning disc is crazy - is that tiny speck the brush? How funny is that they mounted a tiny brush in the middle of an otherwise "normal" playable disc - and that you play some music, the music pauses whilst the laser lens gets a brush-up, then the music/I've finished speech starts up again!

[BearBoy]

Yes, that sort of white blur about halfway across the disc is the brush. Absolutely no idea if it actually does any good. Certainly didn't in this case lol

I've got another cleaning disc which is a head and lens cleaner. That looks like a standard recordable MiniDisc but does have a brush attached to the underside of the disc too. The topside of the disc has some sort of matt pink coating. You supposedly play it to clean the lens and record on it to clean the head. Again, no idea if it actually does anything useful...

[kgallen]

I think it's quite a neat idea! The brush has to be small so that the laser can keep aligned to the ADIP (address in pre-groove) that is used by the machine to keep track of where the laser is on the disc. When the brush passes the lens, there will be a burst of errors (no readable disc information) and a very brief machine panic of "I'm lost" before the brush passes and the laser can find the ADIP again. It probably looks to the machine like a "shock event" which of course it's designed to handle and one of the beautiful things about Minidisc (that CD players never really got working well due to the 1:1 read/output datarate of CDs versus the 5:1 of MD). I bet you don't even hear a gap in the music, due to the 10sec of RAM buffering of ATRAC data. Absolutely wonderful technology in these things!

Given you can use this disc to remove "everyday light dust" from the lens without needing to open the machine (which your everyday user would be well advised against!) it should work ok. However in this case we're looking for another reason. If you're inside the machine, then a wipe of the lens with some isopropyl-alchohol on a swab won't hurt but I feel we might end up elsewhere with this one. Let's hope it's no worst than a ribbon cable reseat...

[kgallen]

2 hours ago, BearBoy said:

Turned on my MDS-JB980 this morning. Screen displays the title of the MiniDisc I had left in the deck overnight. I press play and the name of the first track appears but I can just hear the disc spinning and no audio. After about 10 seconds of this I eject and re-insert the disc at which point I get TOC Reading followed by C13 Read Error.

Initially the title data is still in RAM from when the disc read ok the day before (there is a small lithium backup cell - when you take the lid off, a 15-20mm disc with purple/pink plastic around it). Subsequently ejecting a reinserting the disc, the RAM is cleared and the disc is read to retrieve this title data.

Interesting that prior to the eject you could "play" for 10secs (I assume no C13 error appeared) which would suggest the deck "knew all about the disc" from the data already in RAM but was somehow unable to retrieve any ATRAC data from the main data section of the disc...

[BearBoy]

Thanks Kevin - useful information. I was wondering whether it kept the details of a loaded disc in memory somewhere whilst in standby.

Do you know if those batteries ever need replacing?

I am 99% sure no C13 error appeared when I first tried to play the disc. From what I can remember, I manually ejected the disc as I could hear it spinning and nothing was happening (no audio and no time counter progressing on the screen - just the track name displayed). Like you suggest, I suspect the deck "knew" about the disc but was unable to actually start playing back the audio.

[kgallen]

23 minutes ago, BearBoy said:

Thanks Kevin - useful information. I was wondering whether it kept the details of a loaded disc in memory somewhere whilst in standby.

Sorry it is just "blather". Thinking out loud really and sharing the thoughts. All the better if it's "educational" or useful!

The Sony decks pretty much display the disc name/track name from the moment you turn them on if they already have the disc inside, they know if it's been ejected (TOC cloning aside) so don't bother spinning up the disc to get information they already have. It means playback can start much quicker as they already have the TOC/linked lists in memory so know where to put the laser to get at any requested track. Smart people did this stuff and with the demise of such equipment I fear the world is losing some of the skills of smart product design... 

23 minutes ago, BearBoy said:

Do you know if those batteries ever need replacing?

In practical terms probably not, but like any component there is manufacturing variability and they can fail. Although I've bought "spares" (my MDS-E10 saga is well documented!) I've not needed to replace it in any of my ummm 12-13 decks, including my MDS-JE520 I've had from new (1998, maybe 1999) even though that machine did spend some years in the loft (unfavourable temperature swings for any equipment!). As you'd expect from Sony, it's a top quality Panasonic cell.

A failed cell would probably exhibit as not retaining any machine settings or the data we discuss above. The machine is likely to operate normally when it's powered on (unless the battery failed with a low impedance short, but I don't know whether that is a viable failure mode for such things, probably not.

23 minutes ago, BearBoy said:

I am 99% sure no C13 error appeared when I first tried to play the disc. From what I can remember, I manually ejected the disc as I could hear it spinning and nothing was happening (no audio and no time counter progressing on the screen - just the track name displayed). Like you suggest, I suspect the deck "knew" about the disc but was unable to actually start playing back the audio.

For now, my assumptions are that the lens is clean (enough), the laser and detector block are fine, the spindle motor runs and the servo can track, so we hopefully don't have a major problem. One easy test for now would be the "unplug it for a few minutes" test. I'm not overly familiar with your machine but I suspect it's like my MDS-JE machines in that the on/off power button is "soft" in that it is handled by the machine's microprocessor rather than being a traditional clunky power switch that breaks the mains supply. This means that when plugged in, the machine has some "always on" circuity and is "woken up" by pressing the "power" button. It will be a "soft" button if you can have a disc in the machine with a dirty TOC, and pressing the power button will cause the TOC to be written before the machine "goes to sleep". Similarly on my MDS-JE machines, I can press the Eject button and the machine will eject the disc without "powering on" the machine first (and those smart engineers even put the machine back to sleep once the disc has been ejected).

[BearBoy]

1 hour ago, kgallen said:

One easy test for now would be the "unplug it for a few minutes" test. I'm not overly familiar with your machine but I suspect it's like my MDS-JE machines in that the on/off power button is "soft" in that it is handled by the machine's microprocessor rather than being a traditional clunky power switch that breaks the mains supply. This means that when plugged in, the machine has some "always on" circuity and is "woken up" by pressing the "power" button. It will be a "soft" button if you can have a disc in the machine with a dirty TOC, and pressing the power button will cause the TOC to be written before the machine "goes to sleep". Similarly on my MDS-JE machines, I can press the Eject button and the machine will eject the disc without "powering on" the machine first (and those smart engineers even put the machine back to sleep once the disc has been ejected).

Thanks for the suggestion Kevin. I left the machine unplugged from the mains for about 30 minutes but unfortunately it has not made any difference.

You're right re your suspicion: the MDS-JB980 has a "soft" power button that puts the machine into a standby mode rather than actually powering it off. My MDS-JE500 has a similar "soft" power button on the front panel but also has a "Main Power" switch located on the back, which does actually appear to switch off the machine completely. They seem to have dropped this feature by the time they made the MDS-JB940 and MDS-JB980.

[BearBoy]

1 hour ago, kgallen said:

I've not needed to replace it in any of my ummm 12-13 decks

Ha - I thought I had too many MiniDisc machines

[kgallen]

3 minutes ago, BearBoy said:

Thanks for the suggestion Kevin. I left the machine unplugged from the mains for about 30 minutes but unfortunately it has not made any difference.

I know we haven't solved your issue but I'm kinda relieved it hasn't fixed it! I've never known "switch it off and on again" be a solution on any of my decent equipment. More a "solution" for "lesser designs" and anything computer related.

[kgallen]

19 minutes ago, BearBoy said:

Ha - I thought I had too many MiniDisc machines

I blame this forum for many of mine! :-D

Oh and buying machines for parts and then finding they just need a little fix to make them fully working, rather than breaking for parts. Then seeing a nice one on eBay and not being able to resist it getting past.

I often wonder, if the MDS-JE530 I bought a couple of years back (at the start of my MD resurgence) had worked out of the box (ultimately the ribbon cable joke!), would I have started buying my Tascam machines that lead onto the Sony MDS-E12 that lead on to a duff E10 and trying to fix that, that lead onto... :-D

Maybe I've had a series of MD epochs... the early years (1998-2000, [JE520/R700]), the resurgence (2018), broken down into the "belt" period, the "IIC Stop" period (still ongoing), the "ribbon" period, the "MDM7" period, the "SIF" period (still ongoing and growing) and currently the "LP2" period! For completeness I'm afraid I've never had a HiMD epoch or a NetMD epoch!

Anyway, enough of this! Back to the problem...!

(I just counted, it's 15 machines: 3 portables, 1 system, 11 decks... ooops.)

[sfbp]

Butting in here with a quick thought - any chance the function of the insertion of the cleaning disk that made it work, was to jiggle whatever sensor differentiates between CD and MO? (Easy to ask that from ignorance when I don't actually understand that mechanism).

Stephen

[BearBoy]

So the deck might be trying to read the MO discs as though they were CD discs and is thus unable to?

Kevin mentioned a "dimple" in his earlier post that tells the deck whether the disc is an MO or CD disc. I'll see if I can find out where that is and where the corresponding sensor in the deck is. Might be worth checking that, if I can, when I open the deck up later.

Thanks Stephen.

[kgallen]

It's the hole or otherwise next to the hole that has the write protect tab.

The machine can get the CD/MO information from the disc itself, but it's possible this case coding might help it read the premastered section. I'm still looking in the Primer document for this info, but I think we've covered this before in one of my posts. Stephen and I had a long conversation on this after he pointed me at this doc and I was having a read and learning lots about the technology. Possibly in my MDS-JE530 thread (we went off on one for quite a few posts on our journey of discovery).

Anyway there are two tiny pin switches - one white and one blue - just to the inside of the drive where the WP and "REFRECT" (sic) (=REFLECT) holes end up when the disc is mounted. Possible the REFLECT pin got broken? However the MO discs have the hole and on the CDs the hole is blocked. So in MO discs the pin switch would be "unpressed" as it goes into the hole. If the actuator on the REFLECT switch was broken it would thus read as MO, so I'd expect the deck to read MO disc ok and CD discs possibly not.

Primer Fig 2 (p2) and Figure 14 (p12).

[sfbp]

.... and if the pin DIDN'T go into the hole (ie got stuck pressed in) then the MO disk would appear to the machine as a CD?

 

[BearBoy]

Thanks both. I have located the dimple. Have tried peering through the loading slot but cannot see the pins. Hopefully I'll get a better view when I get inside.

[kgallen]

Not sure if your machine is one of the fancy tray-loading ones. In my machines, the disc goes in horizontally then drops vertically down by 5mm or so to locate the spindle and to lower the holes onto the WP/REF switches. So looking in the slot from the front, the switches are to the left at the front of the machine, but they are lower down than the slot. Easily seen with the drive in your hand, but probably still not easy to see from above with the lid off your machine. You're looking for a white and a blue pin, about 1mm diameter and 2-3mm high.

On the first frame of the YouTube video on this link, you can see the two pins to the left corner, left of his finger. So blue is WP and white is REFLECT.

 

[BearBoy]

My deck is a slot loading one too. I've just inserted a clear recordable disc (with the record protect tab slid into the protected position) and can see a small blue pin through the small hole in the edge of the disc (i.e. where the tab slides into) and am pretty sure I can see a white pin behind the blue one. Without a disc inserted I can see the white pin but the blue one appears to be obscured by a piece of metal, which I think drops down when the disc is inserted.

So it looks like both pins are there and I'm pretty sure they're both poking through the appropriate holes in the recordable disc.

[kgallen]

I don't recall anything but I wonder if in service mode there is anything that tells you what type of disc it thinks is in there. I wonder if any of the service items change based on CD vs MO inserted disc.

Do you have any other CD discs you could try? (With my own escapades I managed to get a copy - at sensible price - of Jeff Wayne's War Of The Worlds 2MD as a "collectable" and as CD-type discs for test purposes. They are my only MD-CDs...)

[BearBoy]

The only CD type disc I have is that lens cleaning disc. I never bothered buying any pre-recorded MiniDisc albums back in the 1990s as it was cheaper to buy the CD and a blank disc. I have looked at a few on eBay more recently but anything I was vaguely interested in seemed to be fairly expensive. I suppose just having anything might be useful for test purposes though.

If the Service Menu does tell you what sort of disc is inserted, I'm not sure I'd be able to access it quick enough before the deck ejects the MO discs following the C13 error message? I'll take a look in the Service Manual and see if I can find anything there.

[kgallen]

In Service Mode, it doesn't try to read the disc in the normal way (you can do naughty things in Service Mode) so C13 wouldn't be an issue :-)

[BearBoy]

:-) Good to know!

[BearBoy]

Well, that was, thankfully, fairly simple to resolve and didn't require me to go messing about in service menus or fiddling with tiny, fragile switches etc. :-)

I took the lid off and gave the laser lens a clean with some isopropyl alcohol. Whilst doing so, I noticed a small hair in the disc mechanism near, but not actually touching, the lens so I removed that as well.

Hey presto, the deck can now read any disc I put into it.

Two things still confuse me somewhat: 

1. Why it suddenly stopped reading discs overnight when I had left a disc in it. I hadn't noticed any gradual increase in the time it took to read the TOC leading up to the issue.
2. Why it was able to read the CD disc cleaning disc without any issues but not any MO discs.

Anyway, the main thing is my deck is now working again and I can put my search for a cheap donor MDS-JE480 back on hold :-)

Thanks for all of your advice and suggestions Kevin and Stephen; they were very much appreciated.

[BearBoy]

Oh, one other thing I seem to have discovered: those lens cleaning discs are not as effective as a cotton bud and some isopropyl alcohol!

[kgallen]

Super! All's well that ends well! Simple explanations are the best. Particularly on fairly costly and treasured pieces of equipment! We'll add 'hair' to the list... Well after we get though this Covid thing, a trip to the barbers will be pretty high on the list!

Hopefully we learned a few things on the way too. I'm still reading that MD technical document in between family and "proper" work! Wikipedia searches tonight have included Wollaston Prism and Canada Balsam :-D

Stephen - can this get any sort of "Solved" badge?