Amplifier Research 75A250A Manual - Page 16
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4.3.1.2
4.3.1.3
4.3.1.4
PS3 J2, Pin 1
PS3 J2, Pin 2
PS3 J2, Pin 6
If output voltages are not present on PS3, check the AC input to PS3.
4.3.1.5
should be as follows:
A4 J3, Pin 16
A4 J3, Pin 29
A4 J3, Pin 31
4.3.1.6
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.
4.3.1.7
arrange for repair or replacement of the A4 Operate/Control Board.
4.3.2 The Unit Cannot be Operated Remotely
4.3.2.1
4.3.2.2
position; if the unit does not operate locally, see subsection 4.3.1 of this manual.
4.3.2.3
Operate/Control Board; 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 subsection 2.2.2 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.)
Check the FUNCTION 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 circuit breaker on
the unit's rear panel; it must be set to the "1" ("ON") position.
4.3.1.3 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.
Check the output voltages from PS3; these voltages should be as follows:
+12.0 ± 0.3VDC
+ 5.0 ± 0.2VDC
-12.0 ± 0.3VDC
Check the voltages to the A4 Operate/Control Board on connector A4 J3; the voltages
-12.0 ± 0.3VDC
+ 5.0 ± 0.2VDC
+12.0 ± 0.3VDC
Check the voltage on A4 J3, Pin 3; it should be ≥4V when the POWER switch (S1) is in
If all voltages are correct and the unit still does not operate, contact Amplifier Research to
Verify that the front panel FUNCTION switch is set to the REMOTE position.
Verify that the unit operates locally by resetting the FUNCTION switch to the LOCAL
Check the position of the "ADDRESS" switch assembly (SW1) on the A4
Manual Text
4-3
REV A