PRG VARI LITE VL5, Service Manual

Page: 59 / 142

VL5 ™ WASH LUMINAIRE SERVICE MANUAL 49
Pan/Tilt Belt Tension Adjustment
Tools:
Wrench, Allen, 5/32", long handled
T-wrench, long handled
Loose pan/tilt drive belts can create calibration problems. When the luminaire reaches the end of travel, excess belt
slack can produce a vibration causing the encoder to continue producing a movement output signal to the processor
(even though the luminaire is at its stop).
To fix this problem, slowly increase the belt tension until the vibration is dampened.
CAUTION: Do not overtighten belt, pulley will break.
To adjust either the pan mechanism or tilt mechanism pulley belt:
Step 1. Pan or tilt luminaire head back and forth, noting the tension created on one side of belt and deflections on
the other. Figure 2-31. .
Figure 2-31: Belt Tension Adjustment
Note: Bilateral deflection may be observed by loosening the tension adjustment screw and rotating the head
assembly. As the head is rotated back and forth, the tension is created on one side and deflections are created on the
other.
Step 2. Using 5/32" Allen wrench, tighten belt tension adjustment screw until no bilateral deflection occurs. For tilt
mechanism, use long handled T-wrench going through hole in top of yoke cross member. (In VL5Arc
luminaire, T-wrench also goes through ignitor board assembly.)
Step 3. Using finger, test belt tension. With proper tension, you should be able to push the belt flat so that it just
touches side rail.
Deflections are present
when belt is loose.
Pan/Tilt Mechanism
Drive Pulley
Driven Pulley
Tension side of belt
Feed side of belt
Belt Tension Adjustment Screw
NOTE: When pushed, belt should just touch rail when tension is adjusted correctly.
Rail
Belt (See note)