T-M50 / T-M50 ASME Service manual
Ver. 1.05
36
CONFIDENTIAL
11. Fault Analysis & Specifications
Remarks:
1. Proper range of values of voltage & resistance shown below.
2. Please refer to the wiring diagram for checkpoint positions.
3. Remove power to water heater when checking for continuity, disconnections, resistance values, etc.
4. The water heater contains 3 PCBs; Central computer and Left /Right PCB
Natural of Fault
Diagnosis
Check
point
1 Check the power supply
[1] Check the power supply from GFI to the central computer board
(Refer to section12-2)
[2] Check the power supply line to the water heater
2 Fault of GFI
Normal: 100 VAC between (white-black)
Normal: 100 VAC between (brown-brown)
A
A1
3 Fault of transformer
[1] Disconnection / breakage of wires
Normal: 120 VAC between (white-black)
Normal: 100 VAC between (brown-brown)
A2,A3
A1
4 Blown fuse at surge box (10 A)
5 Fault of central computer board
[1] No voltage at remote control terminal
Normal: 11 to 25 VDC between (white-black)
F
6 Disconnection/short-circuit/grounding of remote wires
Normal: 11 to 25 VDC between (white-black)
・
No display on
temperature remote
controller, even when
remote is turned on.
7 Fault of PCB of remote control
[1] Check for normal voltage at terminal
・
It takes long time to get
hot water at the fixtures
1 The time it takes to deliver hot water from the water heater to fixtures depends
on the length of piping between them. The longer the distance or the bigger the
pipes, the longer it will take to get hot water.
2 If you need to receive hot water to fixtures quicker, you may want to consider a
hot water recirculation system.
・
The water is not hot
enough
1 Check cross pluming between cold water lines and hot water lines.
2 Check whether the gas supply pressure is enough.
3 Check whether the temperature setting is too low.
・
The water is too hot 1 Check whether the temperature setting is too high.
・
The hot water is not
available when a
fixture is opened
1 Make sure the unit has a 120 VAC / 60Hz power supply.
2 If the remote controller is used, check whether the power button is
turned on.
3 Check that the filter on the cold water inlet is clean.
4 Check whether the hot water fixture is sufficiently open to draw at least
0.5 GM through the water heater.
