Service manual

Electrical Service Manual V4.0

1-10

CENTRAL COMMAND I

TIMER BASED VACUUM SYSTEMS

The following model machines had timer based vacuum systems:

29, 35, 38, 40, 52, 3700 & 5100

There 2 different systems, 1 system for walk behind machines and another for rider ma-

chines.

WALK BEHIND MACHINES

The walk behind timer circuit is very straight forward. Pin #5 on the timer receives +24

Volts from the limit switch that is actuated by the squeegee lift bar. When the squeegee is

lowered the linkage contacts the switch sending +24 Volts from the + Buss bar to Pin #5

of the timer. When the timer receives +24 volts on Pin #5 it would turn on the timer and

output +24 Volts on Pin#3 which is connected to the vacuum solenoid thus turning on the

solenoid. When voltage is removed from pin #5, the timer maintains power on Pin #3 for 21

seconds. When the power is turned off by the timer after the 21 second delay the Vacuum

solenoid then turns off thus turning off the vacuum motor.

DIAGNOSIS

Turn the machine on.

Drop the squeegee assembly with the handle

Measure for battery voltage (+/- 1 volt) at the vacuum motor

If the voltage is OK replace the vac motor

If the voltage is out of spec proceed to the next step.

Check for battery voltage from the positive (+) buss bar to the negative (-) buss bar.

Check for battery voltage at the blue wire on the vacuum switch.

Check for battery voltage at the white wire when the squeegee is lowered

If OK proceed to next step

If there is no voltage make sure the switch is being moved by the squeegee linkage.

If the movement is OK replace the switch. If not adjust the switch.

Check for battery voltage at Pin #5 of the vacuum timer assembly

If there is no voltage then repair the wiring from the vac switch to the timer.

Check for battery voltage out of the timer on Pin #3

If there is battery voltage go to the next step

Using a volt meter set to the DC scale to accommodate 24 volts measure from pin

#2 on the timer to pin #1 there should be battery voltage there. If that is good them

measure from pin #2 to pin #4. There should be battery voltage there if either

of these terminals is missing voltage repair the wiring between the timer and the

buss bars. If there is battery voltage both places replace the timer.

Check for battery voltage on the yellow wire connected to the coil circuit on the vacuum

motor solenoid.

If there is voltage go to the next step

If there is no voltage repair the wiring between pin #3 and the vacuum motor

solenoid.

With the volt meter measure from one coil terminal to the other on the vacuum motor sole-

noid.

If there is battery voltage (+/- 1.5 volts) go to the next step