Date: Tue, 15 Nov 94 13:14:28 CST
Subject: SX50 CRT;water problems; FTP site?; meetings
From:
Status: OR
Here are 5 messages of interest to SX50 users:
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X-Sender: brucer@demperth.per.dem.csiro.au
Date: Tue, 15 Nov 1994 20:49:40 +0800
From: B.Robinson@dem.csiro.au (Bruce Robinson)
Subject: SX monitors, cold water risks
SX green monitors fold-around problem and
Cooling-water low-temperature hazards
Monitor Fold-Over
Terry Harrison, who is the electronics expert in our team, has supplied
the following notes from our maintenance records. Sorry this is late.
Our network dragon devoured the first draft yesterday.
We have fixed the X fold-around problem several times on the Thomson M1
and M2 monitors on our 1987 SX-50. We understand that later SX-50s had
"Clinton" ?brand monitors, which are very similar, I am told.
On our version, we use circuit diagram #29277204 1 of 5. There are three
transistors in the X-driver chain. They are Q2,Q6 and Q3. These are
BD529, BD530 and 2N3792 respectively. We used the equivalents BD131 and
BD132 for Q2 and Q6 as they were easier to get locally. Q3 is the main
driver and is on a vertically mounted board at the back of the Monitor box.
It is in the centre (of 3) in the bottom row (of two rows).
Q2 and Q6 are on the Ampli-X board which is mounted horizontally at the
bottom of the monitor box. The row of transistors nearest the back of
the box (starting from the column edge of the board) are Q22, Q6 and Q2
respectively. Q22 is nearest the column.
We have twice replaced both Q2 and Q6 at the same time, as recommended by
Claudio Cermignani (and presumably Edgar Chavez) at Toronto. Terry's
reason for doing this is that it is very hard to get to the board, so it is
simpler to replace both transistors at once than to risk replacing the
wrong one and have to come back to replace the other. Claudio and Edgar
may have an additional reason.
We have once replaced Q3 to solve the same problem.
********
If any users have a good third-party source of the monitor CROs, we would
like to know. We are thinking of getting a spare CRO tube. Ours have a
metal mounting plate fixed to the glass of the tube.
I would like to thank John Fournelle for keeping the users' list. It
promises to be increasingly useful. Perhaps we could accumulate a set of
maintenance hints like this which could be archived somewhere, so when
people have a problem they can look at the index under Monitors or
whatever.
*********
Under-temperature cooling water warning I have been intending to write a
note about the real risks of cooling water under-temperature. This has
been known to cause condensation of water in the electronics, inside
the lenses in the column and be generally nasty (water can drip from the
water-cooled green monitors down the electronics cards). Early SX's had
no temperature sensors. Later ones have both over and under-temperature
monitors. However, even this is not adequate if the SX power is off with
the cooling water continuing to run. If the water gets cold, below
dew-point, condensation will form in awkward places. When the power is
turned on again, it is too late for the sensors to issue a warning. It is
possible that the water has come back to normal temperature, but the
condensation is still wetting things. I understand that considerable
damage (? "resistors unsoldering themselves and falling on the floor") has
happened even on a temperature-sensored relatively new SX.
Suggestion. Someone should design a simple condensation-check system which
would continuously measure conductivity of a test strip attached to the
cooling system piping. If condensation had occurred, turning the power on
would be prohibited (or the power would be turned off, if it were on.).
The users' group could perhaps collectively design one, and distribute
notes on how to install it.
We have some plastic drip trays under the monitor cooling-pipe brass joints
to catch any drips and convey them to the floor, hopefully by-passing the
electronics. So far, our only problems have been over-temperature in the
water (40 degrees C), for which we have fitted buzzers and a thermal
cut-out. We do not have an "under-temperature" sensor on the SX (yet), but
we do
have one on the new cooling water system.
Regards from Western Australia
Bruce Robinson
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| Bruce Robinson |e-mail: B.Robinson@DEM.CSIRO.AU |
| Electron Beam Laboratory | ,-_|\ |
| CSIRO, Exploration and Mining |fax 61 9 387 6046 /CSIRO\ |
| P.O. Wembley WA 6011 |phone 61 9 387 0378 \_,-._/ |
| AUSTRALIA |home 61 9 384 7409 v |
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Date: Tue, 15 Nov 94 13:31:14 EST
From: "Todd Solberg, VaTech"
Subject: Re: SX50 crt info requested
I believe you would adjust a trim pot inside the monitor for wrap around.
wrap around problem.
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FTP Site for SX50 info???
This idea keeps popping up (as it should), including in Bruce's message
above. Is anyone out there interested in taking responsibility for setting
up an FTP site where SX50 info (maintanance routines, tasks, programs, etc)
could be archived?? If you'd be willing to help out, please send me a
note. Thanks.
- John Fournelle johnf@geology.wisc.edu
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Date: Thu, 10 Nov 94 08:19:38 CST
From: jinnys@rice.edu (Jinny Sisson)
Subject: Re: GSA Meeting
We had a good meeting at GSA. Most really enjoyed the chance to meet each
other. Mike Drake said that he really thought some of the reasons why he
had complaints about Cameca have been cleared up. I hope to have time
later this week to write up a short summary of all that was said and send
it out to all users. I've been out of touch because I had to leave for
another meeting in New Mexico and I just got back last night. Best wishes,
Jinny
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Virginia B. Sisson
Dept of Geology and Geophysics 713-285-5234 (Office)
6100 S. Main St., MS-126 713-285-5214 (Fax)
Rice University
Houston, TX 77005-1892
jinnys@rice.edu
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SX50 users get together at AGU in San Francisco Dec 5-8??
If you're going to the AGU meeting in 3 weeks and would be interested
in getting together with other SX50 users, drop me a line.
- John Fournelle johnf@geology.wisc.edu