Kyocera CD Player Occassionally Can't Lock on Track

When playing straight through, apparently ok, how 'tap-sensitive' is it ? A clean laser in good order should stand a knock to the cabinet that is enough to shake the lens, when there is no disc in - if you see what I mean, That is, not violent enough to guarantee a jump, but hard enough to make a noise. If the laser is clean, but jumps easily when the cabinet is tapped, it is likely that the laser is low emission or dirty internally, either of which problem means replacing it. Again, if it is a laser problem, a burnt disc rather than a pressed one, will usually behave worse, due to its lower reflectivity.

Another possibility, if the player has setup pots, which most these days don't, is that the E-F balance is a little off. This can cause just about exactly the symptoms that you are describing. However, it is often the case that the E-F balance is poor because of internal dust in the laser, and without a pot to offset the opamp that the diodes drive into, you're stuck. If the laser is one of the Sony KSS series - particularly if it is a KSS213B or a KSS240A, then the problem is probably laser related. All the KSS series are readily available from multiple sources, and not expensive. They are not hard to replace in most players, and if you buy a 'genuine' replacement rather than a second source 'ringer', they are usually just 'drop in' without any setting up issues.

Arfa

Thanks Arfa. I went in and posted my results and a picture here:

Optical assy is the KSS-123A and they appear to go for $25. Results of the tap test are inconclusive. It does jerk it a bit, but maybe I'm just hitting it too hard? So, what do you think, adjust the E-F now? In which direction?

I've seen Kyocera's of this type have slightly sagging suspension springs, so that the disc scrapes slightly as it plays. You might check to make sure the disc rotates absolutely freely when clamped in PLAY position and that there is a bit of play in the vertical plane, meaning that the clamper or disc isn't very close to scraping.

Also, sometimes we see other things - even a bit of hair wrapped around the spindle motor shaft can cause a problem, and while we're on the subject, the tray load belt (underneath the mech) is a real troublemaker on these. Perhaps it's just not clamping fully.

Mark Z.

"Rob" wrote in message news: snipped-for-privacy@57g2000hsv.googlegroups.com...

OK. The forum site where you have posted the pics won't let me in without being registered. I'm assuming then, that if you want to try adjustment, you have a full raft of adjustments available ? These should include at least Focus Gain, Tracking Gain, E-F Balance (tracking balance on some players) and Focus Balance.

If you have a 'scope, a good way to make adjustments is by observing the 'eye pattern' waveform. This can normally be found on a testpoint called "RF". As a bit of a 'standard', although not guaranteed, the p-p amplitude of the waveform on here from a laser which is performing to spec, is usually

1v. You need to set a disc playing and get it to around the middle. Adjust the 'scope settings until you have a good solidly locked display, with the timebase opened out enough to be able to clearly see the 'diamonds' in the pattern. The adjustments can then be gently made to make the diamonds as 'stationary' and well defined as possible ie no bounce and no lateral jitter. It will not be possible to get this perfect, as disc imperfections will have an effect, but 'correct' points for each of the pots are usually clearly visible. If you are not experienced in making these adjustments, I would strongly recommend marking their existing positions very clearly, so that you can return to the original settings if needed. Note that you should only use a proper insulated trimmer tool or very small screwdriver to adjust them, *not* an all-metal jewellers screwdriver, as your body will have an effect on the adjustments, via an all-metal tool.

If you have good hearing, but no 'scope, there is an alternative method for adjusting E-F / focus balance. First pick a commercial (pressed) disc that's in less-than-perfect condition. Not so badly scratched that there are going to be playability issues with it, but normal day to day scuffs and light scratches. Start it playing and get to around the middle of the disc. Now turn up the focus gain (normally clockwise on the pot, but not always) and if necessary, the tracking gain until you can hear the laser assembly 'hissing'. You will need to put your ear quite close to the deck to hear it, and it will be virtually non-existent on a 'perfect' disc, so don't use one. You should not need to go more than 3/4 the way up on either of the gain pots to get a clear hiss. Now, listening closely, carefully rock the E-F balance pot a few degrees either side of its current position. If the servo loses lock because you go too far, just return the pot to approximately where it was. The servo will normally recover lock, and the disc will continue to play. You should be able to hear a clearly defined 'dip' in the level of the hiss. Maximum dip - minimum hiss - is the correct setting for the E-F balance. If you have a focus balance pot as well, you can adjust this in the same fashion, to further minimise the noise. Finally, return the gain pots to their original settings. You can leave them up a little to improve the shock handling of the deck, but you will get a higher physical noise level from it, which if you have got good hearing, may be audible on quiet music passages, even with the player's covers on.

Finally, if there is a pot called "PLL" or something similar (normally away from the others) DO NOT alter its setting, as there is a procedure involving disabling the loop and using a frequency counter, which must be adhered to exactly, to correctly set this control. Also, DO NOT touch any pot that is actually on the laser itself, and which is likely paint sealed.

If making these adjustments does not improve the situation, then it is likely that the problem is laser related, although there are other electronic possibilities, involving the servo circuitry. Mercifully, playability problems which are not the laser, are fairly rare on most makes and models.

Arfa

I'm repeating my post here, but there is a photo also, showing the E- F, E-off and F-off pots.

*** So I open her up for an inspection. First off, whats inside:

DAC: BB PCM54HP Optical Assy: KSS-152A Rubycon caps Motors: pickup sled and tray drive: RF-510T; spindle drive: RF-310T-1?? Mabuchi The tray is belt driven and is clearly dry and slipping.

The lens looked clean, but I went ahead and dabbed it down with 99% Iso, also air cleaned the mirror. The assy slides smoothly across the two sled bars.

I connected/disconnected all connectors.

Still, same problem. Seems to always be able to read the startup information (number of tracks, total time), but still occassionally cannot lock on a track when FF or Rev.

It has been suggested to possibly adjust the E-F. Is this advisable? Here is a photo of the pots available.

Any idea how I can get to that belt? There is a screw with suspension on the far end of the transport, but I can't seem to guess how to take her out. The face of the tray appears to be permanently mounted.

***

Apparently, this generation of deck has some intermittent problems with tracking and skipping. Every deck I've seen on eBay is "working perfect", but sold in "as is" condition, so there is the suspicion that other owners are experiencing these issues and not being forthcoming with them (as in my experience).

My problem does not seem significant, I can play straight thru and am not experiencing skipping, just the occasional inability to lock onto a track when using the skip track function. It may not make sense to tamper with it much at this point, though I am going to have to replace the belt. I also have the Dick Smith ESR meter, do you think it would be worth checking the caps? Seems that if this issue is that type that gets worse over time, that it be something like cap degradation? Should I concentrate on the caps around the adjustment pots, perhaps?

Also, in general, if I were to change a laser on a cd deck and the laser is the problem (may or may not be here), is this usually a "drop in" job with no further adjustments? I don't have a scope, but do have most other instrumentation.

If I were to adjust the E-F pot and mark the original position, is it very likely that I will at least be able to get back the operability that I currently have? Would be a shame to tamper with it then end up in a worse situation. What about cleaning the pots, can dirty pots cause these symptoms? You should be able to go to that site to see my type of pot (trim pot, haven't really checked for manufacturer), perhaps you have a cookie issue, it is not the type of site that requires registration.

Thanks for the help, I had not come across that E-F adjustment procedure, I have a pair of stethoscopes that could assist in hearing the symptoms you describe are needed for adjustment.

"Rob" wrote in message news: snipped-for-privacy@n39g2000hsh.googlegroups.com...

You shouldn't need anything other than the naked ear to be able to hear the servo noise. I would not recommend adjusting any pots marked "offset" as you really need to follow manufacturer's procedures to adjust them, but you will be fine with E - F balance and tracking and focus gain. Although E - F balance can be quite critical for proper tracking performance, it's not so critical that a few degrees either side of right, will stop the player from running. You would certainly be no worse off by just returning the pot to its original position. All that this pot is doing, is balancing the opamp to which the "E" and "F" pickup diodes are connected. These two diodes are responsible for keeping the laser's beam running down the centre of the track. If both diodes were perfect, and the beam collating and focusing optics were perfect, then when the beam was centrally on the track, the outputs from the diodes would be identical. Unfortunately, none of these things is perfect, including the opamp itself, so the balance pot is provided to compensate for all the imbalances, and allow the opamp to produce a net zero output when the beam is centrally on the track. If the balance is not set correctly, the beam will be slightly off to one side or the other, which will reduce the level of signal read from the disc, and can result in poor quality tracking servo data being extracted, which will make the servo's performance poor. If the beam is off to one side or the other, the tracking servo will be working hard, and this is the raised servo noise level that you can hear.

As far as replacing a laser goes, if you use a genuine replacement, they are usually just drop in. Cheapo second source types may be a little less forgiving, and require you to set E - F balance.

If you have an ESR meter, and the caps are conventional through-board electrolytics, then by all means check them all. A degree of 'feel' is needed to interpret the results for small low value caps, but I guess if you have a meter, then you are experienced enough with it to know this. There are a couple of older Sony models which used to suffer the sorts of problems that you are experiencing as a result of poor caps. When you do a track jump, the gain of the servo is knocked down to stop it resisting, and then back up again when it reaches where its going to achieve a quick re-lock. There are caps attached to the servo processor IC, which are involved with this procedure.

Arfa

The the edge of the disc appears to scrape some, but only at the beginning of the spin up. I can't figure out why its doing this. The spring does not appear to sag. The clamp is on pretty tight. How would I get the drive out to service the belt? The tray face appears permanently secured so you can't pull inward and the drive appears too large to go thru the front mounting opening.

It's been years since I've done one of these - I don't remember the specific tricks to get into one. I do remember you can stretch the springs a bit to fix the scraping.

Mark Z.

I took another look and I think the entire faceplate needs to come out (held by 6 screws), this sound right?

Sorry, not sure. Newer ones they almost always snap off, but older ones often retained the tray lip with screws. Sometimes it does help to remove the screws which hold down the deck, then remove the faceplate then lift them both, then tilt the tray out. Just about then you generally see how it was supposed to come out in the first place.

:-)

Mark Z.

I took a better look at the spring action. When the tray is out, the center of gravity shifts towards the tray and the unit pivots such as the black rubber washer that is on top of the spring makes contact with the hold down metal washer/screw. When the tray fully retracts, there is about a 1mm gap between the black rubber washer and the metal washer/screw hold down. If I manually raise the rubber washer up to the metal washer/screw, it has no effect on the cd scraping issue. In fact, nothing I do seems to affect this one way or the other. It is only the very outer edge of the disc that appears to rub.

Well, in the past I've had good luck just pulling out the compression springs and stretching them out a bit. Careful not to over-do it, though...

Mark Z.

With the tray closed, I lifted the rear a bit simulating a spring stretch and it did not correct the rubbing. I'll go ahead and stretch it a bit, though, when I disassemble to get at the belt. I'll follow up with the EF adjustments suggested and report back on how things turned out. Very elegant looking player, this is.