Drive Regulator Module Test

TM 10-3930-631-34

waveshape (fig. 9-7). Replace defective circuit control

switch module or defective conduction limit circuit in the

module (para 9-28).

control board, defective power

switch module or

(e) Shorted drive regulator input. Disconnect

defective drive regulator could exist.

the white wire from the S1 terminal of the #1 drive

9-9. Drive Regulator Module Test

regulator. Remove the S1 bus bar (fig. 9-6) from

a. Connect the positive lead of a voltmeter or

between the drive regulator modules. Connect one end

oscilloscope to the test point (1) (fig. 9-6) on the first

of a jumper to the white wire and connect the other end

drive regulator module. Connect the negative lead to

to each drive regulator terminal and individually and

the test point (2).

observe wave form (fig. 9-7) to determine if the module

(1) Sit on the operator's seat.

is shorted. Replace defective drive regulator module

(2) Turn the key switch to ON.

(para 9-28).

(3) Place the forward and reverse switch into a

c. If the pulse width does not vary with ac-

direction.

celerator depression, a defective conduction limit circuit

(4) Depress the accelerator sufficiently to

in the control board, defective power

energize the contactor.

b. The meter should read 1.0 + 0.1 volts or the

wave form should be as shown on figure 9-8. Repeat

this check on all drive regulator modules and replace

defective modules (para. 9-28).

VERTICAL 0.1V/CM

HORIZONTAL 0.1MS/CM

SWITCH:

VERTICAL 0.5V/CM OR 1.0V/CM

HORIZONTAL 1MS/CM

S1 NOT CONNECTED

S1 CONNECTED

0.3V-

2.0V

0.2V-0.1V-

2 PULSES SHOWN

1 PULSE SHOWN

0.1V-

FREQUENCY WILL

0V-

BE 3 TO 5 KHZ

BE 300 HZ

Figure 9-8. Wave forms for drive regulator module.

c. Connect the positive lead of a voltmeter or

frequency, and it will be pulse width modulated. Repeat

this check for each drive regulator module and replace

oscilloscope to the D1 terminal (fig. 9-6) on the first

defective drive regulator modules.

drive regulator. Connect the negative lead to B-.

Disconnect the white wire from the S1 terminal and the

9-10. Drive Current Test

S1 bus bar from the drive regulator. Connect a jumper

a. Connect a current shunt on the battery leads.

wire to the white wire.

Use a scope to measure the peak locked motor current

(1) Sit on the operator's seat.

as follows:

(2) Turn the key switch to ON.

(1) Sit on operator's seat.

(3) Place the forward and reverse lever into a

(2) Turn key switch to ON.

direction.

(3) Set the forward and reverse lever into a

(4) Depress the accelerator sufficiently to

direction.

energize the contactor.

(4) Apply the brake.

d. The voltage on the meter should be less than

(5) Depress the accelerator completely.

0.40 volts or the wave form should be as shown on

(6) The peak current should be 600 amperes

figure 9-8. Apply the white wire jumper to the S1

minimum.

terminal. The magnitude will be approximately 2.0 volts,

b. When using an oscilloscope to check current

the frequency will be the control board

limit the prime consideration is the peak of the

9-13