AR 10045879, Operating And Service Manual

Page: 47 / 54

Model 250U1000
Rev A 29
4.3.1 General - Reading Faults
The Model 250U1000 incorporates relatively simple fault detection circuitry, which makes use of the digital
display panel to alert the user or technician which component(s) need service. Use of these indications can
usually expedite troubleshooting of the amplifier. Most faults can be immediately determined down to the
assembly level. If a reset is still indicated, turn off the RF power signal to the input of the amplifier, read and
record the fault indication displayed on the digital control panel for later reference. Then, use the RESET
function to see if the fault clears. If the fault clears, slowly bring the amplifier’s drive level back up and
ensure that recommended RF power levels are not exceeded. If the fault indication is no longer visible, the
fault may have been brought about by a temporary transient condition, component thermal condition or
excessive RF drive to the amplifier’s input. If the fault does not clear with the RF drive off, some other
problem exists in the amplifier.
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 via the control software on the front panel touch screen as shown in
Figure 2-3 herein. 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.)
4.3.3 Thermal Fault (Schematic Diagram No 10042997, 10044731)
During a Thermal Fault, the front panel display should read THERMAL FAULT.
1. Try to reset the unit; if the unit resets and operates normally, check to see that the cooling fan (B1) is
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 is operating normally, check the voltage at the A12
Control/Fault Board, J5, Pin 23, 26 or 27 should be ≤ 0.1V.
3. If the voltage on A12 J5, pin 23, 26, or 27 is high, check the connection to J3-5 and C53.
4.3.4 Interlock Fault (Schematic Diagram No. 10044731)
The Model 250U1000 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 250U1000 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 display 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?