AR 10046246, Operating And Service Manual

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Model 125A250
24 Rev B
4.3.2 The Unit Cannot Be Operated Remotely
1. Verify that the front panel LOCAL/REMOTE switch is set to the REMOTE position.
2. Verify that the unit operates locally by resetting the LOCAL/REMOTE switch to the LOCAL position; if
the unit does not operate locally, see 4.3.1 of this manual.
3. Check the position of the ADDRESS switch assembly (A10); this assembly can be accessed through the
unit’s rear panel. Check to see that these switches are properly set for either RS-232 or IEEE-488
operation, as desired. (See Section 2 of this manual for the proper ADDRESS switch settings.)
NOTE: Address switches are only read at unit power-up; remove and re-apply AC power (i.e., reset
the circuit breaker) after changes are made.
4.3.3 Thermal Fault (Schematic Diagram No 10046262, 10039874)
During a Thermal Fault, the front panel VFD should read THERMAL FAULT.
1. Try to reset the unit; if the unit resets and operates normally, check to see that the cooling fans B1, B2 are
operating normally and that the air inlet on the bottom of the unit and the air outlets on the rear of the unit
are not blocked.
2. If the unit does not reset and the cooling fans are operating normally, check the voltage at the A4
Control/Fault Board, J13, Pin 28 should be
≤
0.1V.
3. If the voltage on A4 J13, pin 28 is high, check the connection to J3-5 and C53.
4.3.4 Interlock Fault (Schematic Diagram No. 10046262)
The Model 125A250 is equipped with an interlock connector, which is located on the rear panel. The
interlock circuit can be used to sense the openings of doors to screen rooms, test chambers, and so forth, and
to turn off RF energy when these doors are opened.
NOTE: The Model 125A250 is shipped with a mating connector, which has a jumper between Pins 1 and 8,
installed in the rear panel interlock connector. The unit will not operate unless the interlock circuit is
closed.
1. In the event of an Interlock Fault, the front panel VFD should read INTERLOCK FAULT .
2. Check to see if it is safe to be power up the unit—are there personnel present in the screen room, or are
doors to the screen room open?
3. After checking for safety, try to clear the Interlock Fault from the front panel by using the RESET switch.
4. If the Interlock Fault will not clear, check for continuity in the External Interlock Circuit (Pin 1 to Pin 8 in
the connector, which mate with J3 in the rear panel).
5. Check the voltage on A4 J13, pin 29; it should be < 0.1V.
6. If the voltage on A4 J13, pin 29 is high, check the interlock line to ground.