"Sam Goldwasser" wrote in message
...
Meat Plow writes:

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


"N Cook" wrote in message
...
N Cook wrote in message
...
aasdf wrote in message
ups.com...
Hi, I have an old Aiwa CX-NA50 that I bought in 1998. It's a three
CD
(3 CD) mini system. From the beginning it would "reject" certain
CDs..
it would spin them a couple of times, with a slight clicking, might
bring up the track directories every once in awhile, but most often
would skip to the next cd. After about a year of this it wouldn't
play
CDs much any more at all. It's been sitting in the closet since
about
1999. Recently I took it out to play MP3s and XM Radio via an FM
transmitter because the little speakers are excellent.

Today I took it apart and fiddled with the little potentiometer
(potter, pot) inside the machine right next to (behind actually, a
few
inches toward the rear of the machine) the laser. It was a chore
getting it apart and I had to take off the side and part of the
back.
I turned the little potter about 1/8 turn counter-clockwise, and it
started working and now seems to read and play CDs. Whether this
will
"burn out" the laser at some point is not a concern to me since it
wasn't working at all before. I tested it to make sure this was
actually the reason by turning the potter back into the original
position, and sure enough it failed to work again. So I'm
reasonably
sure this is what's the matter with it, or a "kludge" to get around
what is really the matter.

Previously I had tried to clean the laser, to no avail. For those
of
you who have faulty Aiwa systems you should know that there was a
class-action settlement a few years ago that offered to replair the
systems for free, because many of the systems had this problem. It
is
a very common problem. Unfortunately the period of time to take
advantage of that has passed, so now you must do it yourself unless
you
simply want to pitch the system or pay money to have someone else
do
it.

So if your mini CD player is not reading the discs you put in, you
may
want to try this fix. Do this at your own risk.


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
http://home.graffiti.net/diverse:graffiti.net/



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

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.



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: http://www.repairfaq.org/

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