In article , Trevor Wilson
wrote:
Martin "Schöön" wrote:
"Trevor Wilson" writes:


One more question though. Earlier on I tried adjusting the only
potentiometer I could see and if that is the laser intensity
adjustment I may have cranked it up which may be harmful. Any advice
on how to adjust it? I tried, I think, to return the potentiometer to
its original position but I am not sure.

**Unless you have a service manual which includes this adjustment (very
rare nowadays), and/or a laser power meter, you should never attempt to
adjust. So, no advice. Sorry.

I don't know if this will help with commercial laser diodes, but...

When testing exerimental devices one of the standard tricks is to monitor
the voltage and current as you slowly wind up the applied voltage via a
resistor. The curves often have a knee or jump in them at the point where
coherent lasing starts (this is above the current where they light up). If
you find this you can then set the bias just about the knee, and if the
system works, leave it there. This will give you the minimim needed for
lasing, so if it plays discs OK minimises the dissipation and should
maximise life, etc.

I've used this with other types of diode. But I've never repaired or
experimented with commercial optical drives. So don't know their
characteristics.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html