"Michael A. Terrell" wrote in message
...


Gareth Magennis wrote:

Hmm, occasionally I attempt to replace either a laser or complete
laser/motor assembly using cheap generic parts, and it just doesn't work.

Today I recieved 2 x KSM213CCM to replace the ones in a Tascam dual CD
player - DJ type thing with separate remote with pitchbend faders etc.
One works fine, the other doesn't. It clicks, jumps and pops, and
sometimes
takes a while to recognise the disk.
(This particular Tascam unit has a built in anti-shock data buffer)

These KSM units contain the laser assembly, the 2 motors and all the
gearing, to move the laser and spin the disc.

I've tried swapping both complete mechs around, and also swapping the KSM
units from one loading mech to the other. Whatever combination/side I
try,
the fault is always with the same new KSM unit.
(I made sure the right mounting springs went back in the right place - one
pair are silver, the other gold)

Now these KSM assemblies are really, really cheap off ebay. They have to
be
or this just would not be an economical repair. (You can change both
within
half an hour)
They are so cheap that I would expect one or two to be DOA on occasion,
but
this seems to happen too often. Last time it was another KSM213C that
wouldn't behave.

(I am always very careful in handling these things, I never touch any of
the
delicate laser parts/electronics, until they are seated in the loading
mech
and the flexible cable plugged into the laser PCB. It is only then I
remove
the safety short with desolder braid)

So, a couple of questions.

I assume the laser power preset is adjusted during manufacture and should
not need adjusting after fitting. (I tried turning a few degrees either
way, it did not help)
Could there be some kind of incompatibility with the Tascam player (does
it
need its firmware settings readjusted somehow?)

Are these things really just plug and play?

Are these cheapo things often DOA or maladjusted/untested etc?

Have I missed anything else?


Is the soldering iron's tip properly grounded? Our limit at Microdyne
was three ohms form the tip, to the bench's ground connection to the
electrical system.






I'll check that monday. I am starting to wonder if it's me that's killing
these things somehow.

None of them actually died though, they all just wouldn't work properly,
hence all this head scratching.

I'm using this.
http://uk.rs-online.com/web/p/product/5102022/?grossPrice=Y&cm_mmc=UK|Shopping-_-Google+PLA-_-Weller|Soldering+Stations-_-5102022&kpid=&kpid=5102022&istCompanyId=f7e7b05b-2daf-4c0e-8825-3633baf8113b&istItemId=xwiixixli&istBid=tzit&gclid =CJLPxLHG2MUCFUH4wgod9UAAfQ



Cheers,


Gareth.