3 Apr
2011
3 Apr
'11
12:38 p.m.
On Sun, 3 Apr 2011, Tony Duell wrote:
I sort of thought I'd seen them available. Will re-engage my Google-foo
and try again.
The only way to cut the pins off above is to saw the body off with a
rotary cutter in the Dremel tool. Probably still safer than trying to
desolder the entire thing intact.
Excellent point. With the key matrix disconnected it won't think anything
is held down.
The card edges were easy enough to clean. The female edge connectors not
so much. My first pass was to use a brass rotary brush in the Dremel at
low speed. The brush is thin enough to slip down into the body and
soft enough that a light touch won't remove the plating. That took care
of a lot of the grunge. Next, I fold a piece of thin cardboard, soak it
in contact cleaner and run it up and down over the entire length.
The memory card connectors exhibited some "bowing" out in the middle that
was initially preventing connectivity. By carefully working a fine
jeweler's screwdriver behind the pins and bending them out, it started
cooperating. I'm aware that's a "Hail Mary" play that probably limits
their useful life, but it beats replacing them outright.
My experience is that no amount of soaking in anything I've been able to
get my hands on will ever passively remove the green stuff. Is your
experience different? Certainly the vinegar neutralizes the pH, but I've
never actually seen it get the fuzz off everything - particularly not from
gold contacts.
I saw some
information on the web about that, but it's hard to believe any
of the branded items (e.g. punches) will still be available from the
sources cited. Should be an interesting battle! I'm actually surprised
that no enterprising individual has offered sets of foom pads as a
product.
Form what I remembner (never having seen a Lisa, alas), this is a normal
Keytronics capacitive keyboard. I thought that somebody did sell
replacement disk kits for them on Ebay (possibly advertised as being for
some other machine, Sol-20 ??) electrolyte.
If I wiggle the connector the mouse is operational, though.
A good sign. Not looking forward to pulling the old DB9 right-angle
connector from the motherboard... This one is too far gone for cleaning
and will definitely need to be replaced.
I've not seen the old one, but if you can cut off the pins above the PCB,
do so. You can then remove the body of the connector and remove the pins
one a ta time (the easiest way to do this is to melt the solder on the
bottom of the PCB and yank the pins out form the top, then clear the
holes by meltign the solder with an iron on one side of the PCB and
suckign the solderout from the other).
If you can't cut the pins off, you will have to deoslder it in the usual
way. A good solder sucker helps, as does a new tip for said succker (They
splay out with use, the fine hole in a new tip is a major advantage). I
find it helpts ot melt a little new solder onto each connection and then
sukc the whole lot off. Wen you've done all the pins, wiggle them around
in the holes with a screwdrier or pliers and pull the part out. At the end of
the internal self-test (everything passes!) it complains
that the keyboard is not plugged in. I get this result with both
keyboards. Is that the symptom of dead foam disks? Somehow I thought it
would still know a keyboard was out there, so perhaps this is something
Normally dead foam disks mean that some or all of the keys don't work,
the keyboard should be dectededmy the machine. I think you have another
fault.
From waht Iv'e read, the keybaord has a 3
contact connector (1/4" jack
plug?), the connectiuons being a power line,
gorund, and a bidirectional
serial data line. I would open up the keyboard and check it's getting
power, I'd also take the PCB off the key frame (lots of little screws)
and try it again. If it fails then, I would see if the microcontroller in
the keybaord is running, what the data line is doing, etc. else
altogether. There was so much corrosion on the edge connector at the
rear of the CRT cage that it could simply be bad contacts at that point.
Will have to start checking continuity.
I would always clean such connecotrs, things do not work with bad
connections :-) and it's worth eliminating the 'sillies' first. I suspect
a dip in citric acid solution, followed by water and then propan-2-ol
would help a lot here. If it;s the female mart of the connecotor (rather than
the PCB edge
fingers it goes onto) that is corroded, I would consider replacing it.
Most edge connectors are still avaialble. It's tedious trandfering wires
from the old to the new onw (I've done it...) but ti doesn't take that long.
That's a last resort. Odds of getting two huge and two mid-sized Amphenol
bus connectors off the motherboard without destroying it are almost nil.
Certainly my luck on that type of operation is about 0%.
Steve
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