January 2010


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Steven Cogswell <[log in to unmask]>
Reply To:
JEOL-Focused Probe Users List <[log in to unmask]>
Thu, 28 Jan 2010 10:45:45 -0400
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Hello Probe folks;

I'd like to thank the members of this list and others who've replied
to my problems of the broken spectrometer tension cable.  The
consensus appears to be that:

- Nobody likes to do it
- Some people take the baseplate out, and would rather realign it than
try and thread cables in place
- Some people just thread it in place
- It's frustrating and takes a long time no matter how you do it.

I'll venture forth some of my own experiences since I last reported
in.  Re-threading a used-but-intact cable is difficult because of the
kinks in the metal.  I haven't tried a new cable but I suspect it
would be easier.

For the short term "we need this to work again" I fashioned a terrible
solution from... a bungie cord.  Bought some stranded bungie cords,
and pulled out some individual strands, which are much stronger than
rubber bands.

The good part of this solution is that it was fast and easy.  Tie it,
loop it and snap it into place.  It's not pretty, but it does
stabilize the counter's cart.   We get consistent results again from
that spectrometer.

In the meantime I actually ended up being very successful re-threading
with... 50 lb fishing line.

The key to that maneuver was to tie an isolated loop of fishing line
around the turnbuckle pulleys to hold the spring taught before I even
started to thread.  That made the re-threading much easier since I
didn't need a hand to hold the spring and pulleys in place.     The
other advantage is that I could have ten feet of fishing line pulled
out while threading so hands could hold it tight and not have it slip
off.  Then I just tied a loop in the free end at the right length and
snapped it on the cart.    (I start with the loop on the turnbuckle as
seen in the picture, and finish attaching it to the proportional
counter travel cart).

Now, I haven't tried this on our actual production unit yet, but I've
been able to make it work on my parts unit.  The production unit
unfortunately is the spectrometer blocked by the gun pumping line, so
I'll have a tighter space to work in.   Our probe is in such heavy use
that any downtime is trouble.

In a completely unrelated incident on this same 733 we had the air
compressor fail, and in a comedy of cascade ended up toasting the
vacuum system control board (the little board at the lower left when
facing the front of the column, has all those manual valve control
switches on it).  In a pinch we whipped out the same board from our
Parts-733 and installed it and amazingly it worked perfectly,
roughing, hi-vac pumping, venting, everything - except the sample
exchange doesn't work right.   If you run valves manually everything
works, but if you do the automatic pumping for sample exchange
(pushing the button on the front of the door to start evacuating the
sample exchange) it dumps vacuum, gets the vacuum fault and restarts.
I suspect it's just a timing issue and V5 is opening too soon before
other valves have had a chance to close.   In the meantime we're just
venting the specimen chamber to put samples in and out.

Here comes the request, My production 733 (a 'brown' model) has that
circuit board as a VG-24L.  My parts 733 (a 'black' model) has a
VG-12L.  I have schematics for the 24L but not for the 12L (the parts
733's book has a schematic for a VG-24L in it).  I'm currently
repairing the blown-up VG-24L, but I'm wondering if anyone has the
schematic for the VG-12L (which I'm assuming must be different, it has
some components differently placed from the first look).   It's page 5
in my 733's schematic's book.

Ideally I'd like to fix the blown up board, and make whatever mods
need to be done to the 12L board to sample exchange right.

I will say I'm highly impressed that the subtitute board works as well
as it does, considering it's a different board, from a different
edition machine, and is all wonderful discrete analog-digital timing
and control with no fancy microcontroller or microprocessor drive.

Thanks again to you folks for your help, we muchly appreciate it.

Best regards,

Steven Cogswell