Trouble-Shooting And Diagnostics 5.6 - Partlow MRC 7800 Installation, Wiring, Operation Manual

P 40
AGE

Trouble-shooting and Diagnostics 5.6

This section consists of two columns. The first column is a list of some possible instrument
conditions. The second column is a list of steps that should improve the condition. The steps
should be performed in order until the condition improves or all the steps have been com-
pleted. If the instrument condition has not improved, contact the nearest representative or the
factory for assistance.
Trouble-shooting should be performed by qualified personnel using the proper equipment and
following all safety precautions. Whenever possible, the trouble-shooting should be accom-
plished with the electrical power disconnected. The instrument contains static sensitive
components so care should be take to observe anti-static procedures.
Condition
Display(s) is/are blank
Correction Steps
1. Verify that the correct instrument power, as indicated
on the wiring label on the platen, is supplied to TB1
terminals 1 & 2. Check the position of the power
select switch, on 230 VAC models, correctly indicates
the power that is connected to the instrument. If the
switch does not indicate the correct voltage, reposition
as necessary. If the voltage is not correct, check the
power source.
2. Turn off the instrument power. Wait about 5 seconds
then turn the power on again .
3. Turn off the instrument power, open the cover, loosen
the platen hold down screw, and swing the platen out
of the way. Inspect the instrument for poor
connections.
a. The white ribbon cables that connect the
Processor board (Appendix A-1, page 46) to
the platen must be properly aligned and
seated in the sockets.
b. The display board(s) white ribbon cable(s)
pins should be properly aligned and seated in
the sockets on the platen potentiometer
segment board.
c. Inspect the EPROM (U3), RAM (U8) and
microprocessor chips (U5) to see that the
legs are properly seated in their sockets on
the Processor Board (page 46).
d. Close the platen and tighten the hold down
screw. Close the cover and turn on the
power to see if the display(s) will now light.
4. Turn off the instrument power. Press and hold the UP
and DOWN keys. Turn on the power. Hold the keys
pressed for about 10 seconds. If the display(s) light(s)
the model number, Program and Alarm Set mode
parameters will need to be re-entered (pages 26 & 30
or Software Ref. Sheet, page 55, if already filled out).