TRANSWORLD MODEL A1-5020 CONTROL…
So you are experiencing intermittent exposures on your Transworld 300ma (or 600ma)
control. Sometimes this will deteriorate to no exposures.
The exposure circuit is really pretty straightforward. Most of the time the Power
Supply Board is the problem and it must be replaced with a rebuilt board. New boards are
not available. We sell rebuilt boards for $600 exchanged for your old board.
Prices are subject to change without notice.
In the unlikely event you are still having problems, the other culprit can be the
actual exposure switch. These switches are still available and we also stock them as well
as the bucky select and ON/OFF switches. The only difference is the exposure and rotor
switches are momentary contact while the ON/OFF and bucky are ON or OFF selectable. All
use a GE PA-85 bulb for illumination. Factory Service manuals are available from us for
the price of $100 should you desire complete service information.
ADDITIONAL HINTS FROM THE EXPERIENCE BOOK:
Assuming that you get ROTOR…the tube anode spins up and the Backup Contactor RY10
closes:
Verify that a jumper is tight across 14 & 15 terminals of TB4 if a Manual
collimator is in place. If a PBL collimator, try jumpering out 14 & 15 and eliminate
the possibility of collimator interlock problems.
Tighten all accessible terminals in the control. Expecially all terminals on TB3, and
TB4. TB-3 is the vertical strip on the left of the control looking from the front and TB4
is the horizontal terminal strip.
Open the electrical cover box on the HT transformer and tighten all wires, expecially
any Bucky wires that may be involved. If you are experiencing intermittent exposures and
have replaced the Power Supply board, but you are only seeing them on the upright bucky,
then be certain to tighten all bucky connections. I would further suggest trying exposures
with the Buckys both OFF. This will take their associated relay contacts out of the
circuit. You can make an exposure, but of course you will see the grid lines in this
condition. We seldom use buckys anymore, so you could replace the grid with a 103 line
10:1 or use the existing 85 line 8:1 or 10:1 grid. Some came with 12:1 which we think are
an overkill for most medical applications, but so be it.
The exposure switch itself can fail, especialLy after 20 years. It is more difficult to
replace it and the rotor switch and I have not had to do it in a while, but my
recollection is that you must remove the switch panel from the main chassis by removing
various nuts with a nutdriver from the back of the unit. Allow about 45 minutes, and you
will have some wires so solder to the new switch. If I were doing it, I would replace both
the Rotor and Exposure switch (don’t mix them up).
Finally, do a Line Check. If you have a low power line situation and the proper tap is
not selected for incoming power, the machine could intermittently not expose.
In 30 years, we have only had one case where we gave up on this problem because of time
limitations.
If the clinic is concerned about the ongoing service calls for this issue, then we
suggest a high frequency upgrade. Summit makes a wonderful HF control and generator
coupled with tube and cables that will upgrade the system electronically. If all of the
equipment is really worn, the entire system should be replaced with an AMRAD (made by
Summit) medical system. HF generators are available in the 30KW, 50KW, 60KW and up. The
30KW HIGH FREQUENCY single phase version will give the facility the "horsepower"
of a 500ma or 600ma single phase older generator without having to increase the incoming
power line.
Feel free to email me for additional comments or specifics on your situation.
