Microprocessor Display Diagnostics; Microprocessor Replacement & Setup; Figure 5−5 Connector 6Mp Connections; Figure 5−6 Display Test Points - Carrier VECTOR 6500 Operation & Service Manual

5.6 MICROPROCESSOR DISPLAY
DIAGNOSTICS
Before replacing a microprocessor or display, the follow-
ing procedure should be done to determine if the prob-
lem is with the microprocessor, display or interconnect-
ing wiring.
NOTE
For diagnoses of problems with the micropro-
cessor, DataLink data recorder downloading,
file analysis using Reports or use of PC cards,
refer to Section 9.6
CAUTION
Most electronic components are suscepti-
ble to damage caused by electrical static
discharge (ESD). In certain cases, the hu-
man body can have enough static electric-
ity to cause resultant damage to the compo-
nents by touch. This is especially true of the
integrated circuits found in the Advance mi-
croprocessor.
a. Attach a grounded
07-00304-00) and ground it to a good unit frame
ground.
b. With the microprocessor powered up (check the Mi-
croprocessor Status LED - See Figure 2−9 - is blink-
ing at a 1 second pulse) and without removing the
spade connectors, check voltage between micropro-
cessor terminal QC1 (+) and QC2 (-). Minimum
voltage to microprocessor is 11 VDC. If voltage is not
correct, repair wiring to microprocessor.
c. Unplug the 6MP connector from the microprocessor.
d. With the negative meter lead on QC2 (without remov-
ing the spade connector), test voltage at the micro-
processor 6MP1 terminal, see Figure 5−5. If nominal
12 VDC is not present, the microprocessor has failed
and must be replaced.
Figure 5−5 Connector 6MP Connections
62-11389
wrist strap (CTD P/N
6MP1
6MP4
e. With the negative meter lead on QC2 (without remov-
ing the spade connector), test voltage at the micro-
processor 6MP4 terminal, see Figure 5−5. If nominal
5 VDC is not present, the microprocessor has failed
and must be replaced.
f. Plug the 6MP connector back into the micropro-
cessor.
g. Disassemble display to gain access to the display test
points. Refer to Section 8.4.4 for display disas-
sembly.
Figure 5−6 Display Test Points
h. With the negative meter lead on TP12, test voltage at
TP14, see Figure 5−6. If nominal 12 VDC is not
present, check wiring from microprocessor to display.
i. With the negative meter lead on TP13, test voltage at
TP12, see Figure 5−6. If nominal 5 VDC is not
present, check wiring from microprocessor to display.
j. If connections are good, replace the display board.
5.7 MICROPROCESSOR REPLACEMENT & SET-
UP
Under no circumstances should a techni-
cian electrically probe the microprocessor
at any point, other than the connector termi-
nals where the harness attaches. Micropro-
cessor components operate at different
voltage levels and at extremely low current
levels. Improper use of voltmeters, jumper
wires, continuity testers, etc. could perma-
nently damage the microprocessor.
Some microprocessor inputs operate at voltage levels
other than the conventional 12 VDC. These inputs in-
clude but are not limited to the pressure transducers and
temperature sensors. Under no circumstances should
12 VDC be applied at these connection points.
5−8
TP12 TP14
TP13
CAUTION