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C
HAPTER
3. M
AINTENANCE
P
ROCEDURES
3-129
02.9631.0010
CONFIDENTIAL
15 Jan 98
3.3.24.2 Control Interface Board Trimpot Calibration
The control interface board contains offset null trimpots for the pan and tilt
servo circuits. These must be adjusted properly to eliminate jitter in the
pan/tilt mechanisms. Test EPROMs are used to provide zero data to the
digital-to-analog converter that drives the pan/tilt mechanism. The
trimpots are used to zero the output of the servo driver amplifiers with
zero data input. The output of the servo driver located on the low voltage
supply board is measured as the trimpots are tweaked.
Parts:
1 EA
PROM,(PRGMD:27C256-2) VL2B HI TEST (87.7138.0001)
1 EA
PROM,(PRGMD:27C256-2) VL2B LO TEST (87.7138.0002)
1 EA
PROM, (PRGMD:27C256-2) VL2C HI TEST (87.7149.0001)
1 EA
PROM, (PRGMD:27C256-2) VL2C LO TEST (87.7149.0002)
Tools:
Screwdriver, Phillips #1
Screwdriver, Phillips #2
Screwdriver, tweaker
Oscilloscope with 10X probe
Lamp run cheater cable
To calibrate pan/tilt trimpots:
Step 1.
Remove power to luminaire.
Step 2.
Open electronics chassis
Step 3.
Remove lamp control board from card cage. Refer to
paragraph 3-27.
Step 4.
Remove system EPROMs from lamp control board and install
either VL2B or VL2C luminaire test EPROMs. Make sure that
HI and LOW EPROMs are installed in correct positions.
Step 5.
Re-install lamp control board in luminaire.
Step 6.
Secure upper enclosure lid so that luminaire head and yoke can
move freely with lid open. (Clip luminaire safety cable loop to
pan stop.)
Caution:
Luminaire can become unbalanced and tip over in this
position. Exercise caution during this test.
Step 7.
At luminaire thumbwheel switch, set switch to 000.
Step 8.
Connect nine-pin connector end of lamp run cheater cable to
luminaire and then plug other end of cable into AC outlet.
Allow luminaire to run for 5 minutes to heat up low voltage
supply.