94MS20 Rev. B4
9-17
Idle Setting
The idle level occurs when the unit is between exposures and when the
unit is at low power exposures. The idle setting determines the power
and temperature of the lamp while at idle. It also allows for much lower
idle power than was ever attainable before.
This lower power level provides a wider light output range, low power
consumption, lower heat generation, and increased lamp life. At low
power levels, the lamps normally become unstable; if over cooled, they
begin to dissipate less energy, which causes them to cool more. This can
continue until they extinguish. When lamps become hotter at idle, they
become more efficient and dissipate more energy, making them hotter
still. This becomes stable, and is commonly done in conventional light
sources, but will shorten the life of the lamp and waste energy. We have
chosen to servo the cooling, by sensing the lamp condition and adjusting
the cooling to regulate the idle temperature.
The idle setting is done at the factory and is rarely necessary in the field.
Always check all other causes of problems before changing the setting.
If the lamp becomes too cool during operation, the P.C. Board will sense
this level and initiate a warm-up cycle. During warm-up, the shutter will
close and will not open until the unit is sufficiently warm. A symptom
of this is after an exposure is started, the shutter will open then close
again for several seconds before finishing the exposure. This should
only happen if the unit is left for a period of time. Successive rapid
exposures would not fail, since it takes many minutes for the unit to over
cool. The most likely cause of this problem is a defective lamp. This
over cooling situation could also be due to a bad idle capacitor, which
would not allow sufficient energy to the lamp to keep it warm.
!
C
See Shrouding The Lamp before continuing.
After checking the capacitors, mark the factory setting of the trimpot
that is located on the back side of the P.C. Board, in the upper left hand
corner (see P.C. Board Layout). The trimpot sets the lamp idle power
level. Turning the trimpot counterclockwise will first slow the lamp
blower. As the lamp reaches the new idle setting, the blower will speed
up to hold the new level. Setting with a meter is done be measuring the
lamp voltage on the P.C. Board lamp lead hot and lamp lead common
(see P.C. Board Layout). The idle setting is 130V~. The voltage will
increase with a counterclockwise adjustment and decrease with a
clockwise adjustment. This voltage change is a secondary effect, after
the lamp has responded to the change in cooling. The changes should be
done in small increments, waiting 60 seconds between each adjustment
before taking the next reading.
The idle setting affects the power that the lamp attains on warm-up cycle,
before switching to idle and the idle temperature of the lamp. If the
setting is too high (too far counterclockwise), the unit will run at high
power with no cooling, until the thermostat switches the unit off. The
Summary of Contents for OLITE
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