On Sat, 6 Feb 2010 20:42:51 -0000, "ian field"
wrote:


"Mycelium" wrote in
message ...
On Sat, 6 Feb 2010 17:40:02 -0000, "ian field"
wrote:


"Mycelium" wrote in
message ...
On Sat, 06 Feb 2010 14:44:53 GMT, Bob Quintal
wrote:

When I look at the picture labeled chip-cap.gif, i see 2 horrible
looking solder joints. There is insufficient solder. The solder is
crystallized. There is insufficient solder in the meniscus.and it
shows evidence of insufficient heating I do not see any perceptible
bulging out of the cap at either end.

You obviously are unaware of the new solder joint acceptability spec
for RoHS assemblies.

Grainyness is the norm. Also, "modern" motherboard houses have been
using stencils that are too thin for years, so they have all been low on
solder for a long time.

There is no such thing as a clean, bright, shiny solder joint any more.
The days of 63 / 37 perfection are gone.

44780 style LCD modules seem particularly intolerant of lead free solder.

A relative, always looking out for bargains, picked up a DAB radio alarm
clock "reduced to clear" - on getting it home they found it was pretty
much
unusable with the LCD not working, so they passed it on to me for the same
as they paid.

When I opened it up and attempted to pull the LCD's ribbon cable connector
from the PCB receptacle, the ribbon cable pulled out of the solder joints
on
the LCD module instead.

The same relative also has another DAB radio that has an intermittent LCD
backlight, and I have a music centre with dim backlight and intermittent
display.


I still sometimes reminisce about the days of 'zebra strip' attachment
of LCDs, which made them very serviceable. :-)

I had a calculator given to me that failed due to Coka-Cola spillage,
and I took it apart, and cleaned up the strip and strip attachment area,
and reassembled it , and used it for a decade after that. It may still
be around somewhere in storage. I think it was a TI-30 or 35.

IIRC the TI-30 came in 2 versions, one had an aluminium front and the other
was entirely plastic and much thinner, if it is the one I'm thinking of the
LCD glass was clamped directly to the flexiprint by a spring clip in the
aluminium front one. On mine the keypad had suffered long term damp and
can't be dismantled for cleaning, also the traces on the flexiprint were
cracking up - I fixed a couple of them with kynar wire but in the end it had
intermittent segments so I binned it.

The TI numbers could be a bit confusing as some came in both LED & LCD
versions of the same TI-number.

I keep the slim TI-30 on the desk because its simpler than the assortment of
Casios I have, I use the TI when I don't want to volunteer for too much
brain ache all at once.


I think you may be a few version later than the first ones then.

This one had a zebra strip that went between the LCD bare face edge,
and the PCB or flex strip.

I actually had more than one calculator that was configured that way.