A.O. Smith T-H2-DV Service Manual page 52

Error Code
Water control valve fault
(Bypass valve function)
661
1 PCB and bypass valve fault
(Refer to section 10-11 & 10-18)
V isual inspection of Water control valve: connection/breakage of wires,
motor drive locked due to scale buildup, and/or water leakage.
Normal: 13.0 to 16 VDC between (blue-brown)
Normal: ON: 12.5 to 16.0 VDC / OFF: 0 to 1 V
Normal: 1 V Less than (0˚ position)
V isual inspection PCB: connection/breakage of wires and/or burn marks on
the computer board.
Error Code
1 PCB fault
[1] Fault of preparation for the mixing thermistor
701
operation.
[2] Fault of driving circuit for Gas Proportional
Valve(VG
1 Check the PCB and/or gas proportional valve
(Refer to section 10-5 & 10-18)
V isual inspection PCB: connection/breakage of wires and/or burn marks on
the computer board.
V isual inspection gas proportional valve: connection/breakage of wires of
the gas proportional valve.
Normal: 20 to 40 Ωbetween (white) & (red)
Malfunction description
Malfunction description
)
0
T-H2-DV/T-H2-OS Service Manual
Turn off the power or water supply
Diagnosis
Turn off the power or water supply
Diagnosis
52
CONFIDENTIAL
Ver. 1.01
Cancellation method
Checkpoint
Cancellation method
Checkpoint
J
H1