Section 4 -- Maintenance 4-4
© 2008, Satake USA Inc.
(ALL RIGHTS RESERVED)
If a lamp goes out, or is too dim (even after the ballast has increased the lamp
current to maximum), the ballast sends a signal and the lamp fault will be indicated
by LED DS2 or DS3 on the Monitor Control PCB illuminating red (See Figure 2-25).
The lamp ballasts are initially adjusted so that the lamp current (and thus its light
output) is only 50% to 70% of its maximum new capability.
Then as the lamp ages, and the light output decays, the ballast increases the current
to bring the light level back up and maintain it constant. This will continue over a
long period of time as the lamp ages, until the lamp current reaches maximum.
Then lamp fault LED DS2 or DS3 on the Monitor Control PCB will illuminate red,
signaling the need to replace the lamps.
In some applications, more than one type product may be run on the process line. It
may be necessary to sort one product using a certain color of lamps, and to sort
another product using a different color of lamps. If installing lamps of a different
color than previous, select the type of lamp to be installed in the sorter with the
SETUP2 screen (See Section 2.5.2.3).
The SETUP SCREENS are used to set the ScanMasterII lamp ballast to provide the
required amount and color of light for one product, and a different amount and
color of light for another product.
Initial lamp setup is made at the factory. Lamp replacement in the field should be
done according to the following procedure. With the sorter configured for the first
product type to be sorted (correct type of lamps installed) the range of adjustment
of the lamp level is checked for the front and rear lamps. On the SETUP1 screen,
turn the LAMP LEVEL setting to a higher number until the measured voltage no
longer increases. Note this measured voltage. A typical value is 24 volts. Next, turn
the LAMP LEVEL setting to a lower number until the measured voltage no longer
increases. Note this measured voltage. A typical value is 8 volts. The normal setting
is just below the midpoint of this range from high to low. For this typical example,
the new lamp setting would be 14 volts. During the final checkout procedure, the
LAMP LEVEL setting is adjusted to achieve this value for both the front and rear
lamps. This will be an approximate setting of the light level as seen by the
photoresistor on the lower lamp holder in each viewer cabinet. After the final
background setting adjustments have been made and the viewers are up to normal
operating temperature, the final setting of LAMP LEVEL will be made to achieve the
correct voltage value. This PRESET will be saved to memory, so that it can be
recalled when the product is to be run.
If only one type lamp is used, this completes the adjustment. If a second lamp type
will be used, these lamps will be installed and the adjustment process will be
repeated.
WARNING: When changing lamps, do not disconnect the fluorescent lamps with
power on the circuit, as this will permanently damage the regulated power
supply (lamp ballast), and it will have to be replaced. Turn off the power switch
on the front panel before removing the lamps.
It is important to understand how fluorescent lamps age. During operation, the
phosphor deteriorates and the light output decreases. As this occurs, the
photoresistor detects the drop in light level and the lamp ballast automatically
adjusts the power to the lamps in order to bring the light level back to the preset
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