On Feb 8, 7:26 pm, "Arfa Daily" wrote:
wrote in message
...
On Feb 8, 11:49 am, "Arfa Daily" wrote:
wrote in message
...
My Sega CD, which uses the KSS-240a laser assembly, makes a spine
chilling sound when it gets warm.. I believe it to be a cogwheel is
expanding when it warms up..
http://www.youtube.com/watch?v=U55FF7NLgn4
Any ideas on how to actually fix this? The system gets no hotter than
it normally does...
I think that it is highly unlikely that anything is happening to the size
of
any gear wheels. The (very brief) sound that can be heard on your clip,
sounds like the motor pinion slipping against the intermediate drive gear.
On a typical mech that uses any of the KSS series lasers, the most common
cause of this is bad contacts on the laser 'home' switch, normally located
on the spindle / sled motor connection board, right underneath the
turntable. When the contacts don't make very well, the laser homes as
normal, but no signal is generated when it gets there, to tell the system
control micro to shut off the drive to the motor, so it keeps running, and
the gears slip against one another. After a while, the vibration caused by
this often gets the switch contacts to make again briefly, which then
causes
the drive to be cut. My first move would be to clean the switch.
Arfa
An update: I watched the laser move, and when it screeches, it's not
even near the home switch.. The motor spins, and the cogwheel does
move, but misses on the other gear (it never slips on the sled)...
There's a decent amount of play, because if I manually turn the
cogwheel, it does sometime miss too..
Thinking about it, there was an issue with some Sony decks (which this
almost certainly is) with two of the gears being right at either end of
their size tolerance specifications, and there was a mod kit for it with two
new gears. There was a service bulletin about it, as I recall, but I
wouldn't know where to lay hands on it now. If you have a local hifi repair
shop, they will have scrap Sony decks coming out of their ears, as many
warranty replacement lasers were supplied by Sony as whole KSM series decks.
You should be able to get a scrap deck from them, which may not be exactly
the same, but in general, the gears in the sled drive train are, so you can
rob and transplant them into your deck. The other alternative is a bit of a
'bodge'. You can slacken the screws which secure the sled motor, then push a
thin sliver of plastic sheet under the side of the motor closest to the
intermediate gear. When you tighten the screws back up, the motor will have
a very slight 'tilt' towards the intermediate gear, which will improve the
meshing. Not ideal, but I have done similar things in the past, when parts
have not been available, or have been prohibitively expensive.
Arfa
I will check at a local repair center and see if they have one..
Btw, I took the "drive" out, and noticed the home switch did have a
cold solder joint, i fixed it, but no change..
http://img.photobucket.com/albums/v3...gon/cdmech.jpg
http://img.photobucket.com/albums/v3...ragon/cold.jpg
I have an old Sony, and peeking in, it has a KSS 210B drive. Can that
work? Or is it not compatible?