CD player laser (failure modes and service life) - Page 1
Forum section: electronics / repair

author: whatever
author_rank: Contributor
timestamp: January 19, 2024, 07:03:45 pm
content: I'm curious about the service life of CDP lasers from, say, the mid/late 1980s. Some serv. techs suggest 10-15 years (see Ref link); however, these accounts vary considerably.Say, it is a Sony KSS series, a very reliable laser head by reputation , used in a player that has been well treated by the cond. of the CDP on a visual inspection. The laser power trimpot is in the default (center) position with typical white mild caulk that fixes it into factory position.All else held equal: ie. CDP not abused, laser lens is clean, caps are good, one can see the typical red spot in the lens, and the laser does go thru the focus/read dance when looking for a disc.Do laser diodes simply wear out, DIMMING over time/use? I assume this is what the trimmer is for -- to adj. over service life.Is there a difference between power requirements for a laser diode/pickup between, say, reading TOC vs. reading just the reflective surface (disc detect).Or do they fail catastrophically? Simply: they work or they don't.Refs:https://www.diyaudio.com/community/threads/wondering-how-long-the-quality-cd-player-can-last.278327

author: coromonadalix
author_rank: Super Contributor
timestamp: January 19, 2024, 07:59:52 pm
content: some sony kss series where absolute junk, no way they last 15 year, the suspension of the lens dropped down, bad design, changed lots of themmore mechanical problems than electronicstray belts is one of the major problemssome fume on the lens degraded the signal, some cleanup helped

author: CaptDon
author_rank: Super Contributor
timestamp: January 19, 2024, 08:06:12 pm
content: Most of those Sony clamshell players died quickly which was very sad. They made one model that had the 0-9 buttons so you could direct enter a track to be played. D.J.'s loved them but the players didn't last very long. They would get flakey and die a week later.

author: Manolo Mos
author_rank: Contributor
timestamp: January 19, 2024, 09:22:54 pm
content: Maybe KSS laser pickups are reliable, but not very reliable. I prefer JVC optima laser pickups, or Pioneer. JVC maybe have not "reputation", but are more reliable.In DIYaudio I've wrote in some threads, about replace laser diodes in Sony KSS laser pickups.

author: Runco990
author_rank: Frequent Contributor
timestamp: January 21, 2024, 09:09:29 pm
content: Sony KSS pickups were the most replaced pickups back in my shop days. They were and are CHEAP!The most durable pickups were the original Philips CDM-0 and CDM-1's. Followed by the more compact swing arm versions.The least durable are all 3 beam or "modern" pickups. Most of the time they go blind from dust INSIDE the assembly.Laser diodes do wear out, but most of the time a hot shot tech turned up the laser current to compensate for the dust in the pickup. It's a fast downhill from there.I own mostly old Philips based players for their durability. Even though you can't get replacements, the pickups almost never die, it's usually capacitors or other electronic problems.

author: kripton2035
author_rank: Super Contributor
timestamp: January 21, 2024, 09:37:40 pm
content: I have a Proton AC300II cd player, from the 80s(?) that is still working fine !

author: Gyro
author_rank: Super Contributor
timestamp: January 21, 2024, 10:44:11 pm
content: @Runco990: I agree, the single beam CDM-0 to CDM-4 are extremely reliable (CDM-4 probably the most) and problems can almost always be related to other causes, for instance wear on the clamp pivot point causing vibration, and also failure of the electrolytic on the current control signal to the base of the laser driver transistor. The main cause of actual laser failure is people misunderstanding the power adjustment and setting them to excessive current. Some service manuals warn against touching the laser current pot, as it is only supposed to be used for manufacturing / new transport installation. The pickups and decoders are very tolerant of any long term reduction in light output. Other things, like glass optics rather than plastic, not to mention the use of swing-arm radial tracking rather than motor and plastic cog linear tracking, are 'built to last' features of the early CDMs. They were probably the sweet spot in terms of semiconductor lasers having become reliable and later cost reductions.I don't know if triple beam pickups need to work the laser harder, but once they became necessary for access speed in CDROM drives, they also became universal in audio players too. Again, triple beam technology require linear tracking (rather than radial) with guide rails and motor and cogs because of the beam shape. They also require a much more delicate lens assembly with more degrees of movement in the much smaller lens (fine side to side tracking and focus rather than just simple robust focusing), allowing more dust ingress and sensitivity. A few players were produced with linear voice coil tracking but I don't know if they have proved more reliable over the decades.

author: coromonadalix
author_rank: Super Contributor
timestamp: January 22, 2024, 04:01:04 am
content: some high end pioneer copper casing models where very sensitive, a small bang on the bench .... skipsame thing on other models, many where not skipping ...

author: p.larner
author_rank: Frequent Contributor
timestamp: January 22, 2024, 02:40:03 pm
content: what about the bose wave radios,ive 2 that have no laser output,seem to be not repairable?.