AR 20S6G18-L, Operating And Service Manual, Page: 41 / 50

Model 40S6G18-L
Rev E 25
4.3.1 Power On Indication Doesn’t Display on Front Panel when
POWER Switch is Depressed (Schematic Diagram No.
10040925)
1. If the Model 40S6G18-L is operating in an otherwise normal fashion, the front panel LCD display 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.
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 output voltage from PS1; this voltage should be as follows:
PS1, P12, Pin 3,4 + 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 A12A3 Control/Fault Board on connector J15; the voltages should be as follows:
P12, Pin 2 + 5.0
± 0.2VDC
7. Check the voltage on A12A3, J3, 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 A12A1 Control/Fault Board.