"Arfa Daily" wrote in message
...
"Mark Zacharias" wrote in message
eb.com...
"Arfa Daily" wrote in message
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"Samuel M. Goldwasser" wrote in message
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"N_Cook" writes:
Samuel M. Goldwasser wrote in message
...
"N_Cook" writes:
First time for years (no salvaged one on hand) I replaced old with
new
but
had forgotten about those antistatic shorting links, wasting time
trying
to
find the short. Nothing on the box about the shorting link, only
graphic
showing use antistatic wrist strap for assembly
Do they all have these solder-across semicircle land pairs?
This one Sanyo SF-P101 has them , so do KSS213 and K SM213, all ?
Is there something in the laser assembly that is especially prone
to
static
damage?
Yes, the laser diode. There's generally very little circuitry
between the
cable and laser diode and it can be damaged by any number of things
including
ESD.
--
sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
But is a CD laser diode any more susceptible to ESD damage than a bulk
standard red LED or a 1N4148 say, in otherwise the same poor handling
circumstances?
YES! A 1 ns current spike with a peak just above the laser diode's
maximum
rating can destroy it. Accidentally connecting a charged 0.01 uF 5 V
cap
across a laser diode will destroy it. Etc., etc. Look at it the wrong
way.....
--
sam
All absolutely agreed. However, to answer one of Mr Cook's earlier
questions, given that they do have this extreme static sensitivity,
curiously, the answer is no - not all replacement optical blocks *do*
have the laser diode shorted for transit. As well as shorting blobs on
the pcb, other methods of shorting that may be found are a thin metal
plate in the ZIF connector that some have, and a tiny switch that I have
seen fitted to some DVD optical blocks. And of course the solder blobs
on the flexiprint tail rather than on the board, and the 'snip-off'
piece of flexiprint (two varieties) to be found on some Panasonic
lasers.
Arfa
And some models like the KSS-240 have the power limiting circuit built
in; no shorting required.
Mark Z.
Yes indeed. And talking of 240's, have you had problems with some players
which use one - particularly Sonys themselves - just not liking the
generic replacements, and suffering all sorts of playability problems
after replacement ? Whenever I had a Sony in that needed a 240, I always
used to quote for a genuine original part ordered from Sony, but it seems
that they are now no longer available from them. I have just picked one up
for repair from one of my feeder shops, and he has asked me to try a stock
240 in it, but based on experience, I'm pretty sure that it's not going to
provide acceptable performance. I wonder why this should be, given that
there doesn't seem to be a problem with generic replacements in any other
Sony models, or problems using a generic 240 in any non-Sony players ?
Arfa
Hey, Geoff.
Actually there's been so few replaced by me in recent years, I don't think
I've used a generic 240 yet. I've gotten "original Sony" pickups from a
reliable supplier, but none lately, so those "NOS" pickups may be gone.
I do believe that a lot of the "flaky KSS240" problems we experienced over
the years were actually bad flat wires. Had one a couple months back.
Of course I can see where a generic might be shipped unadjusted and that
could be disastrous. The are three adjustments on the 240 as you know, not
just the laser power adjustment. Kind of hard to adjust them while they are
playing!
Mark Z.