MDS-JA22ES C13 Error

[bluecrab]

Any clue as to how I might even begin to go about addressing this issue...JPN MDS-JA22ES, which was working fine, now displays C13 read error and will not read any discs, except for a Maxell Cleaning/Test MD...it reads that fine. I am using a 120v > 100v stepdown that definitely works. I have never had any success fixing a C13, but thought I'd ask just in case. Really a bummer.

 

I now see from a prior thread from 2008 (that I started, regarding an MDS-JB940), that it -could- be the battery. Still, though, don't know why the Maxell Cleaning disc would be read OK but nothing else will. Prepared for the worst.

[PhilippeC]

Please contact jonathanpotato, he can help you I think

http://www.jonathandupre.fr

[NGY]

15 hours ago, bluecrab said:

Prepared for the worst.

You may not need to be, just as of yet.

Did you check the odometers of the unit? To get an idea of the usage of the laser head, whether or not it can be the cause for the error. Over time, as the laser weakens, can lead to read errors. (Also, as once Jim Hoggarth pointed out, a weakening spindle motor can cause a similar problem. But as yours reading the test disc OK, spindle is probably out of question.)

Recently I managed to fix a couple of decks with C13, by properly adjusting the laser power and IOP. If it is the case with your unit, even if C13 was the result of the laser slowly giving up to the ghosts, an adjustment still can give you some time, before replacing the OP becomes necessary.

BTW, replacing the laser with new sparepart is still doable these days (or, find a donor with a less used part), so no need to worry about that your high quality deck goes out of order for good.

 

[NGY]

1 hour ago, PhilippeC said:

Please contact jonathanpotato

It seems that the chance of getting any reply from him is near to zero :-( .

I tried to contact him by at least three different means, still could not get thru. (Luckily, I managed to solve my questions since then, so I stopped chasing him.)

[sfbp]

10 hours ago, bluecrab said:

Any clue as to how I might even begin to go about addressing this issue...JPN MDS-JA22ES, which was working fine, now displays C13 read error and will not read any discs, except for a Maxell Cleaning/Test MD...it reads that fine. I am using a 120v > 100v stepdown that definitely works. I have never had any success fixing a C13, but thought I'd ask just in case. Really a bummer.

 

I now see from a prior thread from 2008 (that I started, regarding an MDS-JB940), that it -could- be the battery. Still, though, don't know why the Maxell Cleaning disc would be read OK but nothing else will. Prepared for the worst.

How can a single disk both clean and be read? I have never had one of these so I am speaking from sublime ignorance. What I have seen for CDs is that there is some kind of brush or abrasive rotating CD-shaped material which one moistens. A truly horrible thing to do to one's optical pickup IMO. If seconds are ticking off it probably means timing information is available but that is NOT the same as actually reading a real MD. I *think* that would mean it is not a mechanical problem.

Another thought.... does it read a prerecorded MD? This is a less demanding test requiring less adjustment prior to its execution. If not it may well be mechanical problems as per Jim.

C13 usually means that IOP is out of whack with the capability of the laser. Fastest way to fix is with a laser power meter (assuming there are no mechanical difficulties). Don't even think about trying to write anything for the moment - the write adjustment is much coarser than the read adjustment, and recording always includes reading back something that was written, so you can have a situation where you wrote something perfectly but the operation cannot complete because in order to write the TOC, it must read it first (after the recording but before the playback, if you see what I mean).

If you don't have a LPM the best advice I can give is to open up the drive and see if the IOP number is written by hand in blue ink on the paper stuck to the top of the laser. It's no use trying to get at the one that's printed and stuck to the bottom of the pickup - that means you take the whole thing apart so now you pretty much need to give the unit the Full Monty. But generally someone will have tested the laser and written on it the IOP value (unfortunately for you, without the decimal point but I am sure you can divide by 10 or 100, should be obvious). Now you need to get in to the service mode and see if that is close to the number for IOP that's been set.

Maybe it's time to follow Gyula's instructions and build your own LPM !?

[bluecrab]

I want to thank all of you for the responses. Despite the apparent unavailability of Jim and Jonathan and my lack of an LPM, I think I may have a few spins left in that JA22ES (which arrived in what looks like near-new condition about a month ago). I let the unit sit unplugged—not just powered off, unplugged—overnight and for now it has at least read one disc. I have been through this before with a JB940...that is, it gave the C13 consistently, and then after a day or two of being unplugged it would work—at least until it didn't and the C13 reappeared.

Stephen, all I can tell you about the Maxell disc—I was surprised myself by how it works—is that you insert it and it is read. There are 6 tracks. The spoken instructions, which start with Tr. 1 or 2, tell you to move to Track 3 to clean. After that there are some sound checks and music samples. There must be some physical diff between the Maxell and ordinary discs. I'll take a look later.

In any case, I find it disheartening that not only is MD so fragile, but also that fixes and replacements are difficult and expensive. I feel like this is beginning of some kind of end for MD for me. This after 17 or 18 years with the format. Thanks again.

Bruce

[Azureal]

Don't say that Bruce!

 

We always have the professionals here for guidance on resolving problems like this ...

[sfbp]

3 hours ago, bluecrab said:

I want to thank all of you for the responses. Despite the apparent unavailability of Jim and Jonathan and my lack of an LPM, I think I may have a few spins left in that JA22ES (which arrived in what looks like near-new condition about a month ago). I let the unit sit unplugged—not just powered off, unplugged—overnight and for now it has at least read one disc. I have been through this before with a JB940...that is, it gave the C13 consistently, and then after a day or two of being unplugged it would work—at least until it didn't and the C13 reappeared.

Stephen, all I can tell you about the Maxell disc—I was surprised myself by how it works—is that you insert it and it is read. There are 6 tracks. The spoken instructions, which start with Tr. 1 or 2, tell you to move to Track 3 to clean. After that there are some sound checks and music samples. There must be some physical diff between the Maxell and ordinary discs. I'll take a look later.

In any case, I find it disheartening that not only is MD so fragile, but also that fixes and replacements are difficult and expensive. I feel like this is beginning of some kind of end for MD for me. This after 17 or 18 years with the format. Thanks again.

Bruce

That's a very appealing design. I still don't much like the idea of randomly scraping my OP ;(

So probably it's heating up. That's definitely a symptom. You may find it runs better with the lid off, hahaha. You will probably see the OP vibrating as it tries to seek. However the likelihood is it's the laser power at this point. You can certainly haul out the BD unit and check the mechanism to see if there is significant (ie different from normal) resistance to seeking using your fingers to turn the stepper motor manually (with the power off of course).

Sadly I cannot help as the drive appears (assuming it's the same as the JA20ES non-Japan model) to be MDM-6A and I do not have a machine with that drive in it. Is that because of the way the disks are loaded? In which case maybe the JA333ES you have may be compatible. You could start swapping bits to see what is actually wrong. They both have the "tray" type of mechanism, correct?

[bluecrab]

Alas, I have neither the 333ES or the prior JA20ES any longer, so there is nothing to swap. (they do both have the tray, though.) Finding it runs better with the lid off is exactly what happened with a 940 that also had a C13. It succumbed eventually, though. It also seems to me that the 22ES's display is dimming.

[sfbp]

Ha! ( I almost typed "HA!") That might be simple to fix. Try running for 5 minutes without the stepdown? I recall the same situation with my PX3, not realising it was supposed to be on 100V when I first got it. However it was indeed the laser power that needed adjusting. Before I

a. fixed the BD (minidisk) unit

b. got a stepdown to 100V

it did used to get very hot.

Maybe you can get proactive and start measuring power supply voltages when it's turned on? Is it possible that your stepdown is not delivering 100VAC?

I wonder what it is that all your units seem to go this way? What's the mains voltage in Reading, MA?

Stephen

[bluecrab]

Mains voltage here is said to be 120v/60hz, as elsewhere in the US. I'm sure there are the usual 100-120 fluctuations. Think I read that on average, 177v would be about right.

The thing about the stepdowns is that I have tried two of them (different brands) with the same result.

So you think that running @120 for 5  minutes won't hurt the unit?

Edit: OK, I plugged it right into the wall outlet. The display got brighter but the C13 Error persists. It seems that when I leave the unit unplugged overnight, then plug it in in the morning, it will read and play one disc. After that...C13.

Edit #2: Further inspection reveals that the Maxell cleaning/test disc is a pre-recorded disc. These are physically different from blanks or home-recorded MDs. The Maxell will be read and will play every time. I feel like this means something, but not sure what.

[sfbp]

Aha, the prerecorded disk is completely different technology from the MO disks. All pointing towards needing to adjust.

However the bad display brightness is very suspicious, coming at the same time as a MO read-write failure.

I assume

a. the disk gets hot when you succeed in playing it

b. if you run so that you can see the overwrite head you will see a lot of oscillation (of the head).

These are signs you need to do a servo adjustment (of the laser power and maybe some other things, though usually not unless the system has been physically abused) in my extremely limited experience. These decks are all built like tanks, however once they get slightly off, there is a danger in running the motorbike completely off the road, if you see what I mean. That wobble will do it.

[bluecrab]

Sigh. Thanks, Stephen. Thus unit looks very far from abused, although the dim display is puzzling. I looked up the servo stuff in the SM...for one thing, I just don't have the necessary gear; for another, I'm not sure that my more-technically-skilled friend does either. Want to go into the MD deck repair business? I am an absolutely ace at getting difficult items shipped! I laugh at international borders! :-)

[NGY]

You may want to try one thing, that you can perform without any special equipment. This process below is taking a chance on the read power setting of the laser (assuming there is no mechanical issue or else, that caused this C13). In other words, you can try to figure out, whether or not it is related to the laser power settings, by a careful and smart adjustment. Smartness here comes from some data, that helps you "fly blindfolded", without making any damage to the device.

(I used to take notes on the settings of every single md deck I can get my hands on, and this little database began showing a nice pattern, that I can use as a reference, when working on a repair - and I refer to this data in the following).

First, if you go to the service menu, and then to laser power check, the first variable is the 0,9 mW laser power setting, related to reading. This variable is displayed as $XX, where XX is a two digit hexadecimal number - take a note of it.

The factory original setting for this first variable is generally somewhere between $0F and $12 (that is, four steps: 0F, 10, 11, 12), vast majority is $10 and $11. Here you will see whether this unit has a proper value, it if does, you can go further (or if it falls out of the range above, then stop there, because there probably had been some adjustments already, and without an LPM it is very risky to move forward).

When adjusting the laser power setting, one step is roughly 0,045 mW (roughly, and is not fully linear, but this approximation is enough for this quick test). Try to increase the $XX value by one step at a time, save, quit, "reboot", check, if no impact, repeat. Max. 4-5 steps will not harm the laser, and should give a result, if this was the cause. If this cannot fix your C13 error, just write back the original value you took note of at the beginning, for the sake of a clean setup, if once a pro wanted to repair the unit.

(One last note: when adjusting the laser power IOP also changes, but IOP can also be adjusted via the hardware, i.e., there is a trimpot on the laser head, normally set between 2,5... 3 kOhm, if it is not the case, the OP was probably tampered sometime - I left this out of the equation.)

[bluecrab]

Thanks NGY. I will have to consult with my friend about this, but I think between the two of us we can at least decide whether to try this. Not needing any special gear is very helpful. I am a little wary of this delicate process, but considering that what  have now is pretty much just a nice-looking DAC, it may well be worth it. Thanks again!

Bruce

[sfbp]

I just had my E909 refuse to spin up, not having been used for a while. Is it possible that the motor simply is sticky and the unit won't spin up?

[bluecrab]

We're going to find out, as my likes-to-repair-gear guy has agreed to take a look. He does not want to solder, but other than that he will keep on looking for a solution until he either gets it or deems it beyond his expertise. He'll be using the SM in conjunction with the invaluable suggestions here. I must say that even if the JA22ES never plays another disc, it is still valuable and worthwhile as an outstanding DAC. I am using it as such as I write this. Thanks again, guys! I'll report on the results when they come in.

[sfbp]

One more tidbit. In the situation you describe it may be despite contrary inferences that you actually need to turn the read power exactly one notch DOWN.

However he should start by looking at the iop number written on the op.

Good luck!

[BearBoy]

Afraid I cannot offer you any technical advice Bluecrab but would like to wish you good luck with getting it fixed. It would be a shame if such a nice player had spun it's last MiniDisc. 

[bluecrab]

Things have not gone well so far with the JA22ES's C13 Disc Error problem.

Here is what is now known (these notes are from the person who has been working on the unit:

Service Mode's self-diagnostic function provided  the following information on the unit:

• The unit has a 'total rec' time of 11 hours.  According to the service manual, this is 1/4 of the actual time spent recording.
• The unit has a 'total play' time of 87 hours.
• The unit has a 'total err' count of 'FF', which is the maximum value.
• The error history (last ten errors) are a collcetion of "E01" (disc error"), "E04" (address cannot be read - servo has deviated), and one "E0B" (not documented).  Six of the errors are E04.

Perhaps all of these counts can be cleared, but right now don't suspect that the original owner ever did so.

Current value of "ldpwr check": the hex value was "10", which is what is considered the initial value.

 

Testing that was performed:

1. Increase ldpwr from 10 to 11.  Restarted unit and still got C13 error.
2. Increase ldpwr from 11 to 12.  Same error.
3. Decreased ldpwr from 12 to 0F.  Same error.
4. Increased ldpwr from 0F to 10.  Same error.
5. Increase ldpwr from 10 to 11.  Same error.
6. Increase ldpwr from 11 to 12.  Same error.
7. Increase ldpwr from 12 to 13.  Same error.
8. Increase ldpwr from 13 to 14.  Same error.
9. Decrease ldpwr from 14 to 11.  Same error.
10. Reset ldpwr back to 10.

 

Looked for POT---could not find the pot, but found the handwritten '54 2'  in expected location.  This matched the C02 setting of 542 in RAM (IOP setting in RAM matched handwritten value), so no difference there.

 

At this point, it's unclear whether the POT should be adjusted  in combination with adjusting ldpwr on the unit.  To further dig around for the POT (which should be adjustable), suspect that a few bits need to be desoldered, which would make everything dicey. 

 

Any thoughts/ideas on what else to try? Guess is that the optical unit may have been heading south and/or the servo mechanism may have been jostled in transit from Japan to US. 

 

I am feeling like this is going to be a dead end, but I did want to report on what has transpired so far.

Many thanks for any clues anyone might have.

[sfbp]

What on earth is POT? I would be adjusting the IOP value not ldpwr right now. Even a couple of clicks can make a difference. Clearly you need a LPM to make this simple.

[NGY]

Great to see you back, and that you gave this nice unit a chance.

I tend to believe the OP is on its way to give up, though it can just as well be some other causes, but from here, the deck would certainly need thorough diagnostics with the proper instruments (DVM, oscilloscope, LPM, test jig, test discs).

If we bet on the weakened OP (I feel those run times are after a possible reset from previous owner/s), seeing the settings you tried did not bring result, turning down the pot on the OP may increase the level of the laser power, but it must be performed together an instant adjustment with the use of an LPM and the test jig with a DMM to avoid burning the OP out. In other words, I would not try even the smallest amount of change on the pot, if these instruments are not available.

(To locate the pot, you can refer to this Service Bulletin)

If we bet on the servo or the focus being out of proper settings, to check/adjust them at least a test jig and an oscilloscope should be at hand. But before that, the error rate can be quickly checked with the use of a test disc generated in the unit (as written in the SM). If the error value is high, i.e., in the couple thousands range, or, plain ”7350”, then we are back to the laser issue, otherwise a setting procedure can be attempted.

OK, I see Stephen just replied while I was writing this, let me read that and then continue.

[NGY]

6 hours ago, sfbp said:

What on earth is POT? I would be adjusting the IOP value not ldpwr right now. Even a couple of clicks can make a difference. Clearly you need a LPM to make this simple.

One can adjust IOP via either the pot or the laser power only - in the setup menu (I mean, that part that is public in the SM) there is no setting for IOP. "Write IOP” is just a note, to record the original IOP value written on the OP, and the result value after setting the laser power.

I forgot to add this: "pot” is an abbreviation (or, electricians' slang, if you like) for "potentiometer", that is, essentially a variable resistor.

[NGY]

Back to the post above: I see your friend knows what he is doing. If it helps you to save the machine, I can offer lending my silly little LPM and the test jig (I hope one of the three types I have will fit this drive, that I've never seen before), with basic instructions, rest is detailed in the SM. Without the battery, this fits a small and light bubblewrap envelope, and should not be expensive to mail it back and forth.

[bluecrab]

Thank you both. I have forwarded your responses and we will go from there for now. NGY, thanks very much for your offer to lend the LPM and test jig. I will let you know if we need them. Very kind and generous of you!

Bruce

[sfbp]

On 5/19/2016 at 10:34 PM, NGY said:

One can adjust IOP via either the pot or the laser power only - in the setup menu (I mean, that part that is public in the SM) there is no setting for IOP. "Write IOP” is just a note, to record the original IOP value written on the OP, and the result value after setting the laser power.

I forgot to add this: "pot” is an abbreviation (or, electricians' slang, if you like) for "potentiometer", that is, essentially a variable resistor.

Are you sure about this? It seems to me that the one time I had this problem with a brand new functioning optical pickup that as soon as the right number (from the pickup) was inscribed in the IOP setting, that the drive commenced working. But my recollection may be faulty, or I may have misunderstood something. And it was a different model with a different mechanism and BD board.

If there are problems with the actual laser power, I suspect the IOP would need a LOWER value for the servo system to respond correctly without calibration, so my first thought would be to leave everything as is and decrease the IOP by one or two (of the smallest digit). You may be surprised.

[NGY]

9 hours ago, sfbp said:

Are you sure about this?

Yes, I am. The SM-s are nearly identical in terms of checking/adjusting, and there is no option to adjust IOP via a variable in the service menu, none of the SM-s I have read mentioned anything like that. Just checked the SM of the JA20ES, and it is nearly word by word the same, as the others'. (IOP is on page 31). Newer models have a "feature", that compares the value on the label of the OP and the value measured when adjusting the laser power, but it has nothing to do with settings, it is just a "health check".

IOP is a measure, that tells how the laser diode is doing, i.e., at what electrical current can the laser emit the required light power. In practice: we adjust the laser power, and check back, how IOP looks like, whether or not it is in the factory defined range. If the laser can emit the required power only at a significantly higher IOP than its nominal value (i.e., more than 10%, or 10 mA according to Sony), that is a sign that the laser diode has (will soon have) a trouble.

[sfbp]

OK, fair enough.

[bluecrab]

Progress has been made. I am going to be concise as possible about what has happened and where things stand with the C13 Error on the JA22ES. I am editing heavily here (from my repair-friend's reports) while trying to retain accuracy.

It was considered that something mechanical, not electrical, might be the root cause of the C13 error.  While the tray mechanism seemed fine, the arm that hovers over the disc above the lens seemed a little stuck.  Moving this arm to the right (as you're facing the unit) indicated some tightness. 

 

After a manual adjustment to the arm was made, a minidisc was read!  Ejecting and reloading the disc led to the C13 error again, but after another manual adjustment of the arm, a minidisc was read once again.  Sequence repeated a few times more, with similar results.

 

A little lightweight grease was applied to two points on the sliders that the arm/lens mechanism slides on, and the slightest of pressure was applied to a spot that was resistant to moving easily (perhaps thrown out of alignment in shipping). The deck began to:

- Play any number of 74 MDs (including Princos that couldn't get read before)

- Play 80-minute MDs (previously failing)

Adjustment was no longer necessary (previously, had to move the arm a little to the right).  The greasing and nudge to a mechanism was all that it took.  Testing continued.

After a few days of playing MDs on the unit without any issue, the C13 occurred again. Despite unplugging the unit overnight, trying different MDs, etc, the issue seemed to be back...but not for good.

The unit was opened up once more, and the drive mechanism (in the MBU-5C section) examined carefully. Two small black teeth had snapped off the mechanism and were stuck in another cog. Repeated careful spinning of the wheels to move the mechanism back and forth generated the click-click noise being heard after a disc was inserted and the head attempted to seek the TOC. The teeth stuck in the cog  were dislodged and removed by using a paper clip with a small amount of grease on its end. Once this was done and the unit reassembled, discs began to play once again.

The two teeth that broke off are part of a track mechanism, with black track on top and white track below it; the white track seems to move somewhat freely from the black track, but normally both move in unison (both the black track teeth and white track teeth are lined up, and are both moved by a cog wheel which is turned, via other cog wheels, by a small electric motor.).  Some of the older grease has been removed, in case there's any chance of a repeat occurrence of the old grease being problematic.

Suspected faulty part officlal part numbers are:

265-4-996-257-01-RACK (SL)

266-4-966-256-01 SL (BASE)

It may be tricky getting to these parts if replacement is desired, as there is no easy way to get at the pieces without desoldering one or two spots on the board beneath the assembly.  The parts are not expensive, but they are not available. They would be good to have on-hand, just in case there's a subsequent issue. At least one other deck (I think it's the JE520) contains these same parts, so perhaps if an old one of these can be found, that would serve as a source for the parts.

The deck at this point is playing back with no issues whatsoever.  Fingers crossed that the deck is happy!

Best guess to how the unit arrived to this state:

• Unit, perhaps nearly brand new, sat in a box for a long time (years, perhaps).

• Unit was powered up, and possibly the first or second time a disc was played, the grease in the mechanism had frozen some movement, causing the teeth to snap, but allowed the unit to play for some period of time.

• Either through shipment or arrival or my initial use, the broken teeth got lodged in the cog, which prevented the mechanism from moving, preventing the head from doing proper seeking, and thus causing the C13 error.

• After the assembly was taken apart for the first time and grease applied to certain locations, that allowed the unit to play for a short time consistently.

• The broken teeth, which were lodged in the cog, moved ever so slightly, causing the mechanism to not move freely.  Once the broken teeth lodged in the cog were removed, the mechanism began to move freely once again.

That is where we now stand. Testing of the unit continues. I will report again as events unfold. Thanks to all!!!

 

 

[NGY]

53 minutes ago, bluecrab said:

Progress has been made.

...

The two teeth that broke off are part of a track mechanism, with black track on top and white track below it; the white track seems to move somewhat freely from the black track, but normally both move in unison (both the black track teeth and white track teeth are lined up, and are both moved by a cog wheel which is turned, via other cog wheels, by a small electric motor.)

...

Either through shipment or arrival or my initial use, the broken teeth got lodged in the cog, which prevented the mechanism from moving, preventing the head from doing proper seeking, and thus causing the C13 error.

 

Great update, thanks for keeping us informed. I was actually waiting for your news, see below why.

What a coincidence, a few days ago I just fixed a deck with a similar error. It was a little S40, that had multiple troubles, C13 was one of them, the one I could fix as the latest, as I kept insisting on it was the laser, without much success. And yes, at the end of the day it did relate to the laser, but just as you wrote, mechanically, not electronically.

I guess you saw something similar, like this below. Lacking an immediate replacement part, I had to take the time to fix the toothed rack - and it went well. The deck is fully operable since then.

I doubted your hi-end machine suffered the same error, so I was reluctant to advice to take this path, and potentially drive your friend crazy. But it seems, he found his way, congratulations.

 

     

 

 

[bluecrab]

"Lacking an immediate replacement part, I had to take the time to fix the toothed rack - and it went well. "

How did you do this? We're looking at missing teeth...how is that fixed without replacing the part?

[NGY]

18 hours ago, bluecrab said:

How did you do this? We're looking at missing teeth...how is that fixed without replacing the part?

"Dental implants" :-) .

Where the two teeth were missing, I cut a "notch" into the rack (see second photo). Then I cut a small block of plastic that would fit tight this notch, from a piece of plastic part I took from another broken Sony drive, so it would match the material. I pressed this block into the opening on the rack, also used a drop of super glue. I kept it in a vise under pressure for a few hours, letting the glue do its job properly. Finally, I shaped the teeth with a precision file. Done.

It holds nicely, and strong enough, because the two teeth have a "root", that can transmit forces to the base of the rack. If I had glued back the teeth only, it would have not held sufficiently, I guess. On the third photo, if you enlarge it, you can notice the outlines of the implanted block.

[bluecrab]

Very well done and I have passed along the info to repair-friend, although I think the current inclination is to leave this as is (couple of missing teeth) unless that breaks.

[sfbp]

Great tale. I am away from the computer a lot at the moment so didn't comment before. I will now, though. This sort of fracture is why people are using (not necessarily buying!) 3-D printers. Not that I am planning to, but every time some piece of equipment is rendered inoperable by a small mass-manufactured piece of plastic getting bust, I think about it.

[Azureal]

Very impressive NYG!

Stephen is right on too.

 

I bought a Printrbot Simple Metal earlier this year and definitely see this as one of the many applications.  My limited experience with designing and printing usable objects tells me that the very fine teeth on the object in question here would likely not print at the resolution required to function as expected.

One would undoubtedly need to perform a simioar operation with a set of small files to shape and fit the part in the same manner as that used by NYG.

 

[bluecrab]

Thought I'd give a sort of intermediate update about the state of the recently repaired JA22ES. The unit is currently in use and is being fully tested for playback (not sure about recording) and is doing well. I expect it to be returned to me sometime later in July. It was agreed that unless and until the couple of missing teeth caused a problem, they could remain missing.

[NGY]

3 hours ago, bluecrab said:

 It was agreed that unless and until the couple of missing teeth caused a problem, they could remain missing.

Just a thought.

The toothed rack positions the laser over the tracks of the md. The black part moves the OP, and the white part compensates the backlash. Backlash is a small amount of play or gap between the gear and the toothed rack, that is needed for smooth and easy transmission, but results a decrease in the precision of positioning, especially when reversing direction.

This gap in our case can be up to two orders of magnitude (!) larger, than the actual track pitch. The white part is tensed against the black one with the help of a spring, thus the actual tooth of the gear is pressed from both sides, and the force of the spring (that is, larger than the force needed to move the OP) eliminates the backlash (to a decent degree, and the rest is taken care of the OP's lens mechanism, see below).

Now, the reason why I mentioned this.

The laser keeps trying to focus and keep in the groove, and even with virtually zero backlash, it may require repositioning a few or more times, depending on different conditions (you can observe this, if you take a look at the OWH of an open drive, while playing a disc). Although the tracking mechanism and the electronics of the drive are designed for this, the focusing part of the OP is also given a load of repositioning and refocusing, that can dramatically increase, if those conditions getting worse (in this case, although the white part's teeth take over the role of the black's broken teeth, without compensation backlash reappears, plus uncertainty in positioning adds, for the white part is not firm on the arm).

Therefore, even if your drive may be able compensate for the missing two teeth without audible errors, in fact the OP must work heavily to find the track and read the information. This extra work can wear the laser way faster, than the normal use.

(Same happens, when the disc itself hits, radial or lateral. Using such discs can speed up the wear of the OP. Certainly, everyday users won't open their decks to check their discs for hitting - I actually began doing it, and am proactively sorting out those, also, if I accidentally drop an md, I immediately check if it still runs true.)

So my point is, to preserve the laser head, it might make sense to have this part replaced, the earlier the better.

[bluecrab]

The JA22ES was, at long last, returned to me yesterday. The repairer  tested it and used it for quite some time, without issue. I briefly tested the unit last night and so far, so good. The repairer considered, NGY, your suggestion to replace the part, but he was concerned about going to that level of complexity—can't say as I blame him for that! The unit will last as long as it does, and that will be that. As much as I would like to use it for recording, I probably won't, in the hope that bot doing so will extend its life. I have a couple of other Type R decks that should do a very good job of recording.

That said, I will note that to my ears, the JA20/22ES sounds as good as or better than any MD deck I have ever owned, including the JA333ES. And it looks great in Champagne color!

:-)

[bluecrab]

Well, why not....here is a pic pf the now-functiioning JA22ES, and my thanks to all! It really is a great-sounding unit.

 

[PhilippeC]

And this is a type-R unit, as a read in recent posts. Do you have your other equipment with that same champagne color ?