710 / 710 ASME Service Manual
Ver. 1.00
29
CONFIDENTIAL
10-14. Computer board
Unit Part #
#701
AOS Part #
319143-279
Checkpoint
N/A
Function
Controls the functions of the most parts in the water heater.
Failure event
Malfunctioning computer
Effects on the water
heater if the computer
board fails
When the computer board failed, the control from the computer and/or
the multi-system control will be abnormal.
The following are the typical examples of when the computers fail:
1. Unable to control proper combustion during operation.
2. Unable to detect correct signals from any/all water heater sensors.
3. Unable to control water valves, which may cause output temperature
fluctuations.
4. Errors in its self-diagnostics. In order to self-diagnose properly, the
computer sends a low voltage signal into its circuit. When the computer
does not detect a return signal, from this circuit, the "701" error code will
appear.
5. Unable to communicate to other computers in the water heater models
and/or the multi-unit controller (Part # 9007675005) during the multi-unit
system operation.
Error codes when the
computer board fails
701
721
741
761
Diagnostic
Visual inspection: connection / breakage of wires and or burn marks on the
computer board.
Color / Number of wires
N/A
8
-
1
/
8
"
(
2
0
6
m
m
)
5 " ( 1 2 9 m m )
1 - 5 / 8 " ( 4 0 m m )