Hobart Brothers 6910, Operation And Maintenance Manual With Illustrated Parts List

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(c) Adjusting for RATED Speed Operation
The function of the new speed control board, is to govern the engine at RATED speed. To
check for proper adjustment, proceed with the following steps:
•
With the engine running and properly adjusted for IDLE speed, flip the engine MODE
switch to the BUILD-UP VOLTAGE setting. The engine should be running at 2000 RPM
and output frequency should be 400Hz.
•
If the reading is high or low, proceed as follows:
With the generator set operating at RATED speed, turn the adjustment pot on the speed
control board in the CLOCKWISE direction to increase RPM’s or COUTERCLOCK-
WISE direction to decrease RPM’s.
After making any adjustments, switch to IDLE speed, allow the engine to stabilize, then
switch back to RATED speed.
(d) Checking the Actuator
The actuator does not require any adjustments. An actuator malfunction, when it occurs, will
result in the actuator being totally inoperative, either due to the actuator coil being open or
shorted to the actuator case. Resistance measurements will reveal either of these conditions.
(e) Checking Operation of Controller Under Load
Apply a load to the generator set, then remove the load and observe the length of time re-
quired for engine speed to again stablize. Engine speed should stabilize within 3 to 5 dimin-
ishing oscilllations. If this does not happen, proceed as follows:
•
With the generator set operating at no load, turn the GAIN setting slightly in the COUNTER-
CLOCKWISE direction.
•
Apply load again to the generator set. Then remove the load again and observe the length
of time required for engine speed to stabilize. It should now stabilize in 3 to 5 diminishing
oscillations.
NOTE: If engine speed STILL doesn’t stabilize, recheck governor linkage. If linkage is set properly, the
governor controller is probably defective.
(f) Checking Magnetic Pick-up signal
Connect a high inpedance voltmeter to magnetic pickup input terminals (10 and 11, Fig. 6) on
controller terminal board. The voltage value at no load, governed speed should be 4-V AC
MINIMUM.
NOTE: A signal as low as 2.5-V is sufficient to operate the control unit satisfactorily. If a no-voltage
condition is indicated, the magnetic pick-up is too far away from flywheel teeth, or it is defective.
May 1/91 Revised 2-3
Page 17
OM-2028