Can anyone tell me how most DVD players detect the disc? I have a JVC XV-N40 Super VCD/DVD/CD player on the fritz. It was providing only a trashy picture until I blew canned air into the port where the disc caddy goes in and out. That gave me an even trashier picture, so I took the cover off and sprayed some CRC QD contact cleaner over the laser/read head (thinking it was already broken, so...) Now it comes up and reports the absence of a disc, even when it has a disc. Have I totally trashed my device, or is there still hope? I did run a Q-Tip in and around the area, but to no avail. I am guessing that the laser is seen to reflect off the disc, and the disc is then spun up to speed for reading. How far wrong am I here? Any help is appreciated. Wondering if I just have ot trash this one...
There is a good chance that you now have an relatively opaque film over the= optics. This will prevent the laser light from passing through and thus n= ot be able to detect a disk. Nothing should ever be sprayed onto or near t= he optics. At this point, try cleaming the surface of the lens using a cott= on swab and alcohol. You have nothing to lose.
There is a good chance that you now have an relatively opaque film over the optics. This will prevent the laser light from passing through and thus not be able to detect a disk. Nothing should ever be sprayed onto or near the optics. At this point, try cleaming the surface of the lens using a cotton swab and alcohol. You have nothing to lose.
Dan
Thank you, Dan. That was basically what I suspected I had done, just didn't think of the alcohol. One question: Radio Shack had a head cleaner which is basically a disk with a line of brush fibers across it. Could this be of any help, do you think? Just wondeirng...
Tried the Q-Tip, both wet and dry, but the laser appeared to be recessed in a small well, which captured anything drifting by and held it in place on top of the laser. Soooo (you are NOT going to believe this) I used my Dremel rotory tool to cut a 1/2" hole in the plastic top of the carriage (with the disc caddy in the OUT position) to reveal the laser sitting precisely underneath where I had cut the hole. Spun a dry Q-tip in the well, and pulled out some debri. Put a data CD in the caddy and pressed IN/OUT. I could actually see the laser running back and forth across the surface of the disc (from the top), as the machine spun the disc up to speed (telling me that it had indeed detected the disc.) Put it all back together and reloaded it underneath the screen in the bedroom, inserted a DVD and watched as the episode selection screen came up. Told it to play all, and it is WORKING. I knew that dremel rotory tool would come in handy, but...
So anyway, you were correct about the semi-opaque film on top of the laser, and I modified the carriage of the DVD reader to allow cleaning of same, so it is now working.
Thanks for your response. If I hadn't gotten your response, I might never have tried what I did. Too bat-shit crazy to have a chance of working. Only it did. I just figured it was trash already, so what did I have to lose?
The need for "cleaning" is completely dependent upon the environment. The = cleaners available with the brushes are a waste of money. Over hte years I = have cleaned 100s of players. The most common cause of problems: Smoking.= Smoke will contaminate the lens over time making the unit extremely sensi= tive to vibrations. Also, those units close to the kitchen often have grea= se films as well.
Disagree. DVD players seem less prone to benefit from cleaning, since they are generally better sealed from the start, but audio cd players often require (and benefit from) cleaning.
The spinning disc does nothing to keep dust from the lens. Even so-called cleaning discs can't do the job, and they have brushes on them.
William may live in a clean place, but many of my customers do not. I've been doing this for 30 years, and measured the level of many CD "eye" patterns before and after cleaning, and have seen up to a 100% improvement - increase in RF level, that is, after cleaning.
For example, often a player will show symptoms first on a CD-R disc before having any issues playing a factory disc - and the same CD-R plays fine after cleaning.
I suppose that we can debate the relevance of years of experience, as I too= have been repairing this equipment for over 30 years, but...
DVD units use a higher power laser light and have a finer granularity of "t= racks" on the disc. While I have not measured the RF levels (I never found= that to be particularly useful), I have had 100s of cases where a good cle= aning of the lens DID restore the unit to proper operation. I suspect that= the light was more scattered by the "dirt" rather than being totally block= ed thus making the reading of the disc difficult.
While this is in no way an absolute solution, it is a simple task that can = sometimes restore proper operation. I have needed to perform grating adust= ments from time to time as well, but that is rare. As with all repair expe= rience, your mileage may vary and will totaly depend upon the number and br= ands of units repaired.
People have often asked me about the reliability of certain brands and mode= ls. I never feel comfortable about making any comments as the only ones I = usually see are the broken ones.
Mostly agree. I think to some extent it depends on the type of crap that we're looking for, and trying to clean. On a standard CD player, the disc does not spin fast enough to have any 'dusting' effect on the lens, so on players that come from a dusty environment, an improvement can often be obtained by manually removing a collection of dust on the top of the lens. I say 'improvement' because cleaning the lens does not, of course, address dust that has also collected on the internal optics of the laser, ie the critical angle mirror and possibly the pickup array where this is located horizontally at the bottom of the head. Never-the-less, removal of the lens dust will often restore near full spec performance. A less satisfactory outcome is often the case where the lens is 'filmy' from tobacco smoke. Whilst the lens is easily cleaned with IPA, the film on the internal optics is likely to be as bad as the one on the lens, and although the laser may be recovered enough to again play discs, the performance is often still badly degraded, and from a service point of view, the only good outcome of this is that you will have proved that the base cause of its original failure to read discs, is indeed the laser, and not a circuitry problem.
DVD decks spin the disc much faster, and the rotating disc pulls a good wodge of air round with it. In my long experience of servicing the things, this makes it very rare for a DVD laser to appear on the bench, with a dusty lens. The exception to this is if the player has stood unused for a long period of time. Filmy lenses from smoke are much more common, and because of the more critical nature of data recovery from a DVD, I have found that cleaning seldom achieves a satisfactory result, presumably because scattering of the laser light on the film covered internal optics, just creates too many errors in the data stream.
As to the cleaning discs with a brush on them, my advice is to never ever - that's NEVER - try to use one, particularly in a DVD player. On most CD player lasers, the lens has a sort of 'wall' raised around its edge, and all this serves to do, is deflect the brush bristles so that at best, a few of them skate across the very middle of the lens. However, on a DVD deck, the laser head is often rather more 'petite' and delicate than a CD laser, and on more than one occasion, I have seen a laser destroyed by the bristles getting caught in the lens suspension, ripping this off its mount. Presumably, it's the high rotational speed that causes this.
Finally, I think that the OP has been incredibly lucky that his - how shall we say ? less than conventional maybe ? - attempts to restore operation to the unit, have not resulted in its total destruction ! :-)
Thank you, Arfa, for this informative post. And I don't think I could agree with you more that my unconventional approach and it's success had as much to do with luck as with planning or care in execution.. Thus, my earlier comment about it being "too bat-shit crazy to have a chance of working." But, like Dan suggested, what did I have to lose? :) Will probably never try anything quite like that again, but I doubt I'll forget it.
Have enjoyed following the conversation, and picking up tidbits on DVD players here and there.
I don't want to get into an argument over minor points, but...
I'm a non-smoker, and have never lived in an unusually dusty environment. I'm sure I'm hardly alone in //never// having had to clean an optical-disk player. (This includes two LV machines, two DVD players, one Blu-ray player, an SACD player, multiple computer drives, and I-don't-know-how-many CD players, including portables.)
I agree that cigarette smoke and cooking vapors (especially oils) are the most-likely cause of a dirty lens. They get there because they settle on -- then stick to -- the lens. Plain dust doesn't stick to the lens, so it can be blown away when the disk spins.
A moving surface drags air with it. (This is why dust tends to settle in corners -- there's no air motion at those surfaces.) This moving air should have //some// effect on non-sticky dust. I believe Geneva (Nortronics) made a faux CD with shallow vanes on the surface to increase the air motion. (It should be in the garage. I'll look for it.)
In my opinion, a regularly used optical-disk player is not going to accumulate much, if any, plain dust on its lens. I remain to be convinced otherwise.
Another point -- has does /any/ contaminant get on the surface of the lens? If you argue that it's pulled in by the spinning disk, then... Well, you draw the conclusion.
As far as I know, the optical system in most optical-disk players is a sealed unit.
Quite often the internal portions of the assembly can be sealed. We are ta= lking about the surface of the lens itself.
Pioneer had an interesting way of combatting this problem... Their CD playe= rs had the optics mounted upside-down. If you recall, either the tray or t= he cartridge for these players required the CD to be label side down. They= did have another problem though, quite often, teh lens would fall out and = end up inside the machine. I have many listings in my repair log for these= repairs. These were frequent enough such that players that were otherwise= unserviceable were canabalized for the lenses. (I still have a few in stoc= k now.)
Modern optical blocks are rarely if ever sealed against getting contamination inside them. It's actually hard to seal them, unless you have a window of high optical quality glass under the lens, sealing the top of the optical chamber. By far the most common arrangement is for the lens to sit in its suspension, which obviously has to be free to move in all directions, right over the top of an open-ended vertical tube that leads down into the chamber which contains the critical angle mirror etc. On some compact lasers such as are found on slim DVD decks, the lens sits pretty much right over the top of the open optics. Very early Sony KSS150A lasers had a 'window' over the optics chamber, and when one of these came in with a dusty lens, it was the norm to flip the plastic cover off the head, gently move the lens out of the way with the tip of a scalpel, and clean this window. Once the '150 was replaced with the '210, the window had gone, and I don't think any of the (many) KSS series lasers that Sony have produced since, have had such a window. I seem to recall that one of the early JVC lasers had a similar arrangement - the Optima 6 or 7B maybe ? - but I might be wrong on that.
As to your contention that CD lasers shouldn't get dusty because of the air layer under the rotating disc, it simply isn't right. I'm sure that we've had this conversation before, and I'm also sure that more than just me has said that a dusty lens, even on regularly used players, is by far the most common problem that causes CD players to fetch up on our benches for repair. The extensive range of Aiwa 3 and 5 disc carousel all-in-ones are particularly prone to the problem, and over the years have made me a lot of money in service work cleaning and replacing lasers in them. Lens contamination from smoke and cooking vapours is not, in my experience, the "most likely" cause of a dirty lens, it is just an *alternative* cause. Fairly common, yes, but by no means the *most* common. Plain loose dust 100% holds that award.
You are right in that DVD players are different in this regard, because of the high rotational speed of the disc, but then I had already explained that in my previous post. For sure, on these lasers, film contamination *is* the most likely cause of a 'dirty' lens rather than loose dust, but as I also explained, because of the semi-open nature of the optics, the vapour-laden air will get inside and condense out to coat the optics - including the underside of the lens - resulting in compromised performance, even if the lens upper surface is restored to a Windex sparkle.
As to why you have not had a problem with your optical players, I think you answered your own observation. You are not a smoker, and you don't live in a particularly dusty environment. Of course you are not alone in this, and I guess many thousands of people enjoy similar trouble-free performance from their players, but many others do smoke and do live in a shit-hole, and they are the ones whose players we see in the world of service. Another factor is the type of player. I think that from what you have said in the past, you tend to go for more up-market equipment. Generally, CD and DVD players that fall into this category, have closed-in unvented cabinets. Basically, except through the tray opening, there is nowhere for dust and other airborne contaminants to get inside. However, that's not the case where a player is integrated into an all-in-one, where they may be in a cavernous enclosure with a nice hot amplifier in the bottom creating circulating air currents to carry the dust around that it drags in through the scores of air vent slots in the base and back. The situation is, of course, further exacerbated by the inclusion of fans ...
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