Unit Shuts Off - Noritz NR501-OD Service Manual

902 Combustion abnormality
Only connect and disconnect the connector after the fan has
stopped rotating and then disconnect the electrical power.
(The Circuit Board and Fan Motor may be damaged otherwise.)
Check the Dip Switch settings.
Normal
Check whether the p i r m a y r g
Normal * Check the r p m i a y r r p
Check whether the manifold gas pressure is normal.
Normal Abnormal
Check whether the manifold gas pressure can be adjusted.
Normal
Check for clogging of the heat exchanger,
deformation or clogging of fan blades, etc.
Normal
Check the carry over of burners.
Normal
During combustion, change the
hot water temperature and
water ow, and through the
peephole of the burner, check
that the number of burners
ignited switches normally.
A
Abnormal
Abnormal
s a r p s e sure is normal.
s e u s e r y b pressing a d n o h i d l g n b t o t h e h
Abnormal
Chec k the voltage of t e h G s a r P
Normal
CN 10: between Red 4 - Blue 3
* When adjusting
1
the gas manifold
2
3 BL
pressure, the
4 R
voltage change
5 W
6
O
within the range
7 GY
8 BK
DC 0.3 - 15V .
9
10 W
11
BL
12
13 W
14
15 BL
<CN10>
Abnormal
Chec k the voltage of Gas Solenoid Valve-2
(SV2) and Gas Solenoid Valve-3 (SV3) .
Normal
During combustion, press the "Maxmum Manifold
Pressure Set Button" and check the voltage below.
(SV2 )
CN10 : Gr ay 7 - Blue 11
1
DC 1-16 V
1
2
3 BL
4 R
5 W
6 O
7 GY
8 BK
9
10
W
11 BL
12
13 W
14
15 BL
<CN10>
50
<Condition of occurrence for error code 902>
"Output/FF+FB No .
(Maintenance #52 / Maintenance #51
M x a m i u m M n a o f i d l P e r s s r u a e nd Minimun Manifold Pressure Set Button .
Abnormal
p o r o o i t i n g n a V v l . e
Circuit Board
14
12 W
13
11 Y
12 BL
10 O
11 W
9 R
10 R
8
9 Y
7
8
Main
6 BK
7
5 V
6 BK Circuit
4 G
5 BK
3 O
Board
4 W
2 Y
3 W
1 W
2 BK
<CN59>
1 W
1
<CN63> 2
1 2 3
4 3 2 1
3
4 BL
<CN135>
4 R
3 BL
BR Y BL R
5
O
2 BL
6 Y <CN27>
1 R
7 W
<CN142>
<CN78> <CN104>
2
1 3 R
1
BL 2
2 BL
3 BL
4 1 G
R
5 W
<CN101>
6
O
7 GY
8 BK <CN10>
9
10 W
<CN89B>
11 BL
3
12
2
6 BK
13 W
1
5 R 14
15
4 BL <CN75>
3 2 1
3
2 W
BL/W R/ R G
1 W
<CN42> <CN89A> <CN102>
Check for improper connection of wir ing,
then replace the Gas Valve.
Abnormal
Inspect for clogging of the heat exchanger,
abnormality of fan blades, etc.
Adjust the manifold gas pressure to a correct value.
Abnormal
(SV3 )
CN10 : Orange 6 - Blue 11
2
DC 1-16 V
Circuit Board
14
12 W
13
11 Y
12 BL
10 O
11
W
9 R
10 R
8
9 Y
7
8 Main
6 BK
7
5 V
Circuit
6 BK
4 G
5 BK
Board 3 O
4
W
2 Y
3 W
1 W
2 BK
<CN59>
1 W
1
<CN63>
1 2 3 2
3 4 3 2 1
4 BL
<CN135>
4 R
3 BL BR Y BL R
5 O
2 BL
6 <CN27>
Y
1 R
7 W
<CN142>
<CN78> <CN104>
2 3 R
1
1 BL 2
2 BL
3 BL
4 R 1 G
5 W
<CN101>
6 O
7
GY
8 BK <CN10>
9
10 W
<CN89B>
11 BL
3
12
2
6 BK 13 W
1
5 R 14
15 BL <CN75>
4
3 2 1
3
2 W
BL/W R/ R G
1 W
<CN42> <CN102>
<CN89A>
Check for the or
Plat e, then replace the Manifold Plate that
does not open.
50%"
50%)
To correct the setting
Check the gas supply
valve, etc.
Primary gas pressure list
Gas group
LP NG
Pressure
Maximum
14.0 10.5
inch H O
2
pressure
Standard
11.0 7.0
inch H O
2
pressure
Minimum
8.0 4.0
inch H O
2
pressure
Replace the Circuit Board set.
* It is not necessary to replace the
Display Window Circuit Board.
Display Window
Fuse
Circuit Board
Data
Display
W 3 1 W
BK 4 2 BK
Po wer
Circuit <CN92>
Board
Dip Switch
1 2 3 4
R BL BL BL
<CN142>
Replace the Circuit Board set.
* It is not necessary to replace the
Display Window Circuit Board.
Display Window
Fuse
Circuit Board
Data
Display
W 3 1 W
BK 4 2 BK
Po wer
Circuit <CN92>
Board
Dip Switch
1 2 3 4
R BL BL BL
<CN142>
fold