
94MS41 Rev C1 S/W Ver. 2.06
13-5
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The internal interlock is a loop that travels through the light head, passing
through the glass switch and two thermostats. This interlock is in series
with the control circuit of the large relays in the power supply. When the
interlock is opened, the relays will open and cut the power to the lamp
terminals. The PC board senses the drop in voltage and closes the shutter.
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The first place to check is the glass switch. The switch lever is located
near the edge of the glass on the end of the lamp where the cable enters.
By releasing the glass, the lever can be seen. If the lever can slip past the
glass, it should be bent slightly toward the reflector. If the switch is closed,
the loop can be traced. First measure the voltage between lamp wires (#4
AC Common) and wire (#10 Interlock). The presence of voltage between
these terminals indicates an open loop. This loop travels to the lamp
head on wire (#10), then to the glass switch, the far end thermostat, the
near end thermostat and terminates on wire (#4). The thermostats are
mounted in the air tubes leading to the lamp. There are no splices in the
air tubes.
Lamp Voltage
The lamp voltage measurement can provide useful information for lamp
striking, lamp output, and level switching information. The meter used
to measure can cause different results. We use traditional needle
movement meters in our factory, due to the trigger pulses on the lamp
before striking. The waveforms are not sinusoidal, so different meters
may produce different results. Here is a chart with typical measurements:
Lamp Voltage (Terminals 2 & 3)
Lamp Fan Voltage (Terminals 4 & 5)
Model
Idle/Low
Med.
High
Trig.
Idle/Low
Med.
High
Trig.
AL56/AL56-480 w/L1280
360-380
380-410
415-445
500+
80-95
90-120
115-125
115-125
AL56/AL56-480 w/L1281
400-430
420-490
440-510
500+
80-95
90-120
115-125
115-125
AL56/AL56-480 w/L1282
400-430
420-490
440-510
500+
80-95
90-120
115-125
115-125
AL66 w/L1280
360-380
380-410
415-445
500+
65-85
80-110
100-110
100-110
AL66 w/L1281
400-430
420-490
440-510
500+
65-85
80-110
100-110
100-110
AL66 w/L1282
400-430
420-490
440-510
500+
65-85
80-110
100-110
100-110
Lamp Power Path
The basic path that the power to the lamp takes is almost identical for all
units. The basic path is incoming line, main power relay, ballasts,
capacitors, trigger board, and then the lamp. See the point to point wiring
diagrams for each light source in Section 16.