> 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.