AR 100A400AM20, Operating And Service Manual

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Model 100A400AM20
Rev A 25
4.3.1 Power On Indication Doesn’t Display on Front Panel Vacuum
Fluorescent Display (VFD) when POWER Switch is Depressed
(Schematic 10042447)
1. If the Model 100A400AM20 is operating in an otherwise normal fashion, the front panel VFD or the
wiring to it could be defective.
2. Check the LOCAL/REMOTE switch on the unit’s front panel; it must be set to the LOCAL position in
order to operate the front panel POWER switch. Check the AC switch on the unit’s rear panel; it must be
set to the “1” (ON) position. Check the AC fuses in the power entry module.
3. If the POWER ON indication is not displayed and the cooling fan (Blower B1) is not running, check to
see that the unit is plugged into a live outlet and that the AC line cord is plugged securely into the unit.
4. Check the +5V housekeeping output voltage from PS1; this voltage should be as follows:
PS1, P8, Pin 1
+ 5.0 ± 0.2VDC
5. If output voltage is not present on PS1, check the AC input to PS1.
6. Check the voltage to the A4 Control/Fault Board on connector J3; the voltages should be as follows:
J3, Pin 2 + 5.0
± 0.2VDC
7. Check the voltage on A4 J10, Pin 1; it should be
≥
3.3V when the POWER switch (S1) is in the normal
position and < 0.1V when S1 is depressed. S1 is normally open; it is closed only when it is depressed.
The amplifier should change state every time the
POWER
switch is depressed.
8. If all voltages are correct and the unit still does not operate, contact AR to arrange for repair or
replacement of the A4 Control/Fault Board.