Repair manual

CALIBRATION & ADJUSTMENTS
5-26
I. Dual Autoluma Rework
The following rework procedure eliminates calibration error due to CRT drift. The rework
includes changing the firmware (EPROMs U8 and U9) on the logic board and the addition of two
resistors on the monitor board. The procedure also requires standard calibration equipment (refer
to the beginning of this section) and the additional material listed below. To perform the rework,
use the steps below. Mechanical and electrical schematics are also included for reference.
Required Materials
Item Quantity Polaroid Part #
1.84 EPROM U8* 1 CPS368
1.84 ERPOM U9* 1 CPS369
1.84 Gentest* 1 13437
2.49M 1/4W 1% resistor* 1 791326M
26AWG solid wire
* Available through Polaroid Material Services
Rework Procedure
Follow ESD precautions to avoid damage to components
1. Unplug the Digital Palette and remove the top cover (six screws).
2. Remove the monitor board from the system (three screws and all connections).
3. To add resistors, drill four holes (#65 bit) above R7 HCENTER pot leaving adequate
distance between conductors. Insert two resistors on component side and route three
jumper wires on etch side. (Refer to the next page for mechanical layout.)
4. Replace EPROMs U8 and U9 with 1.84 version EPROMs.
5. Reinstall the monitor board in the system.
6. For calibration of autoluma, turn on the Digital Palette and allow a 15-minute warmup
time. To prevent ambient light from affecting the readings, make sure the Digital Palette is
covered during these adjustments.
7. Using the Gentest diskette, bring up the main menu by typing GEN184.BAT.
8. Press F2, AUTOLUMINANT ADJUSTMENT, to access DARK CURRENT ADJUST.
9. Following the Gentest procedure, set the dark current to 4 by adjusting VR3 on the logic
board. The dark current level will actively appear on the Gentest menu.