I fixed my Aiwa CD Player!

This is actually not good *general* advice. Be sure that the laser will now totally fail in pretty short order. The laser pot is neither intended to be, nor ever should be, adjusted with 99% of the lasers used in audio and DVD equipment. It's setting is carefully determined at the factory as a result of measuring several parameters. One notable exception is Pioneer, where there is a proper laid down procedure for adjusting it.

I have repaired many thousands of Aiwas over the years, but far from saying that laser failure in them is common because of any manufacturing or design problem, I would venture that the reason I have seen so many, is that I service them for the trade, and they were a very popular item, sold through several of the large chains here, so as a value for money item, which I believe they are, they outsold many other brands and models.

The laser employed in them is one of the KSS series from Sony, and these lasers are extremely cheap anyway, so if you've gone to the trouble of stripping the unit far enough to get at the pot, you might as well replace the laser.

I am pleased for you that adjusting the pot got your unit going to your satisfaction, but it was possible that the fault lay elsewhere, and adjusting the laser would only have compounded the problem by resulting in laser damage. For that reason, if no other, I would STRONGLY advise anyone reading this thread, to NEVER adjust a laser as part of a diagnosis procedure, unless it is a valid and manufacturer-recommended procedure. Some lasers are very expensive ( and very reliable ), and altering the pot on them, when the real problem may well be some two penny resistor, is likely to result in a written off unit.

Arfa

For anyone else seeing this in the archives etc. You should have measured the ohmage of that preset to the nearest ohm with a DVM/resistance first, so you could get back to the initial starting point , if you had made matters worse.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

afterthought. Do not adjust this pot any more than 2 to 5 percent up or down of its original setting, hence requirement to measure firstly.

However, as I said, it really should not be adjusted in the first place. Some optical blocks are very sensitive to abuse, and even if setting the pot back to the original point - which incidentally can usually be achieved by setting the paint seal that you've fractured back to where it was ... - the damage may already have been done, giving you the possibility that you now have two faults. Unless you have the necessary diagnostic skills to know exactly what you are doing, and which laser types are likely to respond, and which to fail as a result of altering their pots, and are prepared to shell out on a shiny new replacement, that still might not work if the problem is elsewhere, then my strong recommendation has to be don't adjust the pot at all, ever.

Arfa

On Thu, 07 Dec 2006 11:42:15 +0000, Arfa Daily Has Frothed:

He had a soon to be 19 year old combo that's been sitting in the closet for almost 8 years. No harm in tinkering with the laser pot.

The OP said 1998, not 1988...

I have no problem with a slight adjustment to get it going if cleaning fails. In my experience the laser diode has a range if operating current within which it's OK. Every cd player laser circuit has an APC circuit to maintain diode current. As the laser weakens, the circuit juices it up some anyway. The OP's solution isn't perfect, to be sure - but the only alternative is to replace the laser, which actually is a LOT more disassembly to remove the whole CD unit, remove the main CD board for access, remove the CD subchassis, replace the pickup, re-assembly, etc. The cost of a KSS pickup isn't too bad from some suppliers, but from Aiwa or Sony could be cost-prohibitive. so the OP would need to hunt down a generic distributor.... The list of caveats for the OP gets longer and longer the more I consider the issue. Considering the class of the Aiwa in question, I say just tweak the pot a bit and run her 'til she dies, which could easily be a couple more years.

Mark Z.

Yes there is. If he had blown the laser, it wouldn't have been obvious as there would still probably be some indication of light from it and he would then spend 3 more days trying to fix a problem which at that point was hopeless without a new pickup.

If the laser output has to be turned up, it probably means that there is a loss of signal somewhere else due to dirty optics or some other cause. The lsaer power is regulated by optical feedback inside the laser diode package and that will try to maintain the same output power until the laser itself is no longer able to provide it, regardless of current.

--- sam | Sci.Electronics.Repair FAQ:

Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs.

Yes Sam, agreed. That is the point exactly. I did say that I was pleased for the OP that he had got his CD player working in this way, but the point that I took issue with was that this should be offered to others on the group as general good advice, and a first thing to try if cleaning did not cure the problem. KSS series lasers are cheap - even from Sony / Aiwa, and the generics are almost cheaper than the postage from many suppliers. Most of the Aiwa models, if you are used to working on them, can have their lasers replaced from the top, without having to dismantle all the bottom end, but even if you prefer to do it the 'long' way, it is but a few minutes extra work. I stand by my original contention that in the professional repair field, laser adjustment, except as I have detailed for the likes of Pioneer, should not be considered an option unless you have properly explored all other potential causes of the problem, and feel that you really must have a tweak to try and prove a low output laser to yourself. Having proved such, the laser should then be replaced, not left turned up. Amateur repairers, who have no 'feel' for carrying out such adjustments, should not attempt them, as they might wreck a previously functional laser that was not responsible for the original problem.

Arfa

On Thu, 07 Dec 2006 08:37:17 -0500, Sam Goldwasser Has Frothed:

My reply was based upon that If the OP was smart enough to tweak the pot he's obviously smart enough to return it if and when he replaced the laser.

On Thu, 07 Dec 2006 12:57:21 +0000, Mark D. Zacharias Has Frothed:

Need to clean my glasses.

Exactly my thoughts. It's not like it's a high end $1000.00 player or a repair for a customer as it was the OP's own unit. Bump the pot and maybe get another year or better out of it. After that if you want to fix it right replace the optics and recal.

On Thu, 07 Dec 2006 14:45:27 +0000, Arfa Daily Has Frothed:

He disclaimered his kludge with "do it at your own risk" that was good enough warning for me.

I've found that tweaking up the laser power on the "too cheap to fix" DVD players made in Eastern Europe get a few more months life out of them.

It's better than nothing. There are no parts available for them, and even if they were, they cost less than the shop time to fix them.

I gave up and took an old computer, a video card with a TV out, a standard DVD-ROM drive and an old remote control, added in MythTV, and got a DVD and almost anything else player. Sometime's it's anoying, and the setup was not really easy, but it works, and keeps working.

Geoff.

On Thu, 07 Dec 2006 16:51:14 +0000, Geoffrey S. Mendelson Has Frothed:

That's another point.

Thanks for the replies guys. Didn't realize this would generate so much controversy. I'm just a shmo who had a piece of equipment he thought wasn't ever going to work again, and certainly wasn't willing to pay half the purchase price to get it fixed. I definitely am not an engineer nor would I recommend any electronic repairman do what I did. But I didn't have any fancy gadgets that you mention to analyze the system, I just had a philips head screwdriver. I don't even know what that pot does! I assume it turns up the power of the laser. But I was just thrilled it worked at all that I figured I'd put it here for anybody who is my situation. It was a little project to distract myself from studying for finals :)

Keep up the good work and thanks for the informative replies!

aasdf

No problem ! Made for a lively and interesting debate anyway. Good luck with the finals, and as I said, glad the solution worked for you.

Arfa

On Thu, 07 Dec 2006 23:21:29 -0800, aasdf Has Frothed:

LOL some of these guys get a little over zealous. I knew from your initial post that you really had nothing to lose by what you did. And I support tinkerers and experimenters in the right situations. I'm self taught myself. 51 yrs old that soldered his first joint back in 1969 when I was taken in by a hobbiest and taught the rudimentary skills. I've done factory service for a whole slew of brand names since then. I specialize now in professional audio, mostly high wattage solid state power amps and tube amps.

"Meat Plow" wrote in message news: snipped-for-privacy@nntp.sun-meatplow.local...

I know what you're saying Meat, but I think you are missing the point of what I was saying. Any of us on here that are professionally involved in electronics service, could see the post and the poster for what it was, and I really didn't have a problem with him getting his (old) unit going by tweaking the pot - we've all done it. But by the same token, there are other amateurs that come on here to learn, and if they are going to do that, they might as well learn properly, as I am sure that you have done over the years after your hobbyist start. No one would advocate twiddling with pots that you don't even know what they do, and in the case of a laser power pot, it is one of the surest ways to compound whatever the original problem was. That was all I was trying to say for the benefit of learners who wanted the professional take on whether or not it was a good idea to attack this pot as a means of diagnosing a bad laser. Just as a matter of interest, we're about the same age so have come through the rapid advancement of microelectronics together. I don't know about you, but I find it harder and harder to keep up as the years roll by. I don't know whether its that the technology is advancing so fast, or whether I've lost the enthusiasm of youth, but I seem to find myself just not wanting to be bothered with it all any more. Was the time when I read nothing but technical journals. These days, I get more out of reading the newspaper ... ;~)

Arfa

On Sat, 09 Dec 2006 00:04:26 +0000, Arfa Daily Has Frothed:

My Panasonic PT51 was the first advanced deviced I've worked on in awhile. Still haven't got the left side converge tweaked (guess I need to go copy the service manual for instructions on the service man mode since nobody chimed in here) I'm out of the current tech loop and that's why I stick to the stuff I know like SS and tube amps (pro audio). I along with siblings own a music store so there is no shortage of repairs. I'm also a ham radio operator for 17 years and work on rf power amps and blocks. I guess my favorite things to repair employ tubes and I'm an avid tube audio buff. I always enjoy reading your posts and can tell you are very savvy in the industry and you do always mean well. Take care.

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There was a time when I used to regularly buy ETI and Wireless World, then only looking at them occassionally in a library and then not even that. First time for years I looked at one in the library recently , forget which mag, but all it had in it was Spice modelling, or similar simulations, and not one bit of hands-on anything

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on