We have received a few reports concerning erratic operation of teh LCD
clock display when the Main dial is rotated, or the VBT or SLOPE TUNE
controls are operated. This appears as if you had pressed the SET, SCROLL,
or GRAPH switches.
This erratic operation may be caused by improper timing of the input pulses
applied to the auxiliary display microprocessor, IC1.
Perform this modification only if the symptom occurs, as a repair. This
change is not required otherwise.
This symptom is easily corrected by replacing IC2 MBM2764-30T1 with
MBM2764-30T2, on Digital Unit A. Early models of the improved IC will
carry the old nomenclature but will be distinguished by a white dot on the
top of the chip.
After the IC has been changed reset the main microprocessor by
pressing and holding the A=B key, and then turning the power switch OFF and
then back ON. Then release the A=B key.
After this change is made the sub-display will not immediately track
the main display. A slight delay has been introduced int he new IC to
prevent any timing errors. It may take approximately 0.5 seconds for the
LCD to track the main display.
Please return the old IC2 to the Service Department along with the WSR
Time required for this modification is 1 hour or less.