On Jun 8, 8:10*pm, "Arfa Daily" wrote:
"N_Cook" wrote in message

...









Dumped so I thought I may as well have a go at lens cleaning and pot
twiddling.
Recognised No Disc but would eject all CD and DVD
Cleaned lens but same
Service manual out there for this, but nothing on the optical deck ,
presumably
DR-02 IPT-2-1, no useful info out there
Sony part number comes up as nothing
2 SMD presets available to twiddle near the lasers
originally 302R and 470R readings
Decreased both, so readings of 254R and 391 , no disc reading
Turned up to 329R and 540R
Now reads all CDs and 4 out of 5 times reads DVDs, I've not (wasted) a
DVD-R
on this yet.
Continue twiddling a bit ?
Would be nice to know what these 2 presets do, is there any convention in
relation to closeness to
the 2 lasers as to which one is which. Both are returned to ground.

If the two pots are mounted on the optical block, then they are almost
certainly the power pots for the two laser diodes. In my experience,
increasing the laser power to get an optical block going again, is a very
short term fix. The increase in laser current from the original nominal
amount which produced the design output power, invariably seems to lead to
total failure in fairly short order ...

Laser diodes are, I believe, quite critical in this respect, and are easily
damaged from being over-driven. Probably a heat thing.

Arfa

I was under the impression that it wasn't just a power issue but
waveform as well. It may be possible to boost power by shotgunning it.
I've done it with audio CD's and it sometimes does work but to achieve
the proper waveform without a scope on it I think would be virtually
impossible. Lenny