Generac Power Systems NP-40G - Manual (Page 101)

Section 7.1- GENERATOR & SPEED CONTROL SYSTEM
Troubleshooting Reference Chart
PROBLEM POSSIBLE CAUSE REMEDY PAGE
1. Engine starts, accelerates,
shuts down at 4500 rpm
a. Carburetor linkage sticking with
throttle stuck open.
B. Stepper Motor failed or seized.
c. Stepper Motor wire connections
broken or disconnected.
d. Stepper Motor not properly
connected.
a. Repair sticking throttle
b. Replace Stepper Motor.
c. Reconnect or repair.
d. Reconnect wires.
3.4-3
3.6- 1
3.6- 1
3.6- 1
2. Overvoltage condition and
speed control system cannot
reduce output voltage.
a. Carburetor linkage sticking with
throttle stuck partly open.
b. Stepper Motor failed or seized.
c. Connection to Stepper Motor Is
broken/dlsconnected with throttle
open.
d. Stepper Motor not properly conn­
ected.
a. Repair sticking throttle.
b. Replace Stepper Motor.
c. Repair or replace connections.
d. Reconnect Stepper Motor wires.
3.4-3
3.6- 1
3.6- 1
3.6- 1
3. Engine speed Is maintained
and no-load voltage is good.
However, when load Is applied
output voltage drops and eng­
ine shuts down.
a. Carburetor linkage sticking with
throttle partly open.
b. StepiMr Motor failed or seized.
c. Connectlonm to Stepper Motor
Motor broken or disconnected.
d. Stepper Motor not properly
connected.
a. Repair sticking throttle.
b. Replace Stepper Motor.
c. Repair or replace connections.
d. Reconnect Stepper Motor.
3.4-3
3.6- 1
3.6- 1
3.6- 1
4. Engine does not accelerate
when load Is applied. After 10
seconds, engine shuts down.
a. Carburetor linkage sticking
with throttle stuck closed.
b. Stepper Motor failed or seized.
c. Stepper Motor not property
connected.
a. Repair sticking throttle.
b. Replace Stwper Motor.
c. Reconnect Stepper Motor.
3.4-3
3.6- 1
3.6- 1
5. Engine speed and AC output
voltage erratic under constant
load. AC output does not turn
off Intermittently.
a. Stepper Motor failure.
b. Connection to Stepper Motor
broken or disconnected.
c. Stepper Motor not properly
connected.
d. CCQ board failure (erratic de­
tection of "zero voltage* cross­
ings).
a. Replace Stepper Motor.
b. Repair or replace connections.
c. Reconnect Stepper Motor.
d. Replace CCG Circuit Board.
3.6- 1
3.6- 1
3.6- 1
1.5-4
6. Engine starts but Stepper
Motor does not move. Shut down
occurs after several seconds.
a. Power Supply winding (PS1,
PS2) Is open.
b. Stator Timing winding Is open.
c. Power supply winding In Stator
shorted to ground (See NOTE 1).
d. Timing winding in Stator shorted
to ground.
e. CCQ board does not detect
‘Zero Voltage* crossings.
a. Repair Ir replace bad wlre(s) PS1/PS2
or replace Stator.
b. Repalr/replace bad wlre(s) TIM1/TIM2 or
replace Stator.
c. Replace Stator.
d. Replace Stator.
e. Replace CCG circuit board.
1.5- 2
1.5- 2
1.5- 2
1.5- 2
1.5- 4
7. Engine shuts down but over-
speed above 4500 rpm did not
occur. e. One of four power windings In
Stator Is open.
b. Main windings shorted to ground.
c. Bad switch In Genistor.
d. No gate connection between CCQ
board and Genistor.
e. No connection between Genistor
and Stator (AC1, AC2, SL1, SL2)
f. CCG board failure.
a. Repalr/replace bad wire(s) AC1/AC2 or
SL1/SL2 or replace Stator.
b. Replace Stator.
c. Replace Genistor.
d. Repalr/replace bad wlre(s) or replace bad
CCG circuit board.
e. Repair or replace connecting wlre(s).
f. Replace CCQ circuit board.
1.5- 1
1.5- 1
1.5- 3
1.5- 4
1.5- 3
1.5- 4
8. AC output turns off Intermittent­
ly. Then, engine runs at Idle for 5
seconds. Finally, AC turns back
on and unit runs normally.
a. CCG board failure. a. Replace CCQ circuit board. 1.5-4
9. Under heavy load, output turns
off and engine speed drops to
Idle. a. CCQ circuit board failure. a. Replace CCQ circuit board. 1.5-4
NOTE 1- Shorted power supply win clings may cause circuit board ground trace to show evidence of burning.
Page 7.1-1