Komatsu 830E Shop Manual page 258

9. ALT. TERTIARY OVERCURRENT - ISOA6 : alt tert current = 0.0 ac amps
(Screen value AC amps = 275 x DC input voltage).
NOTE: Prior to testing, the PTU screen will display erroneous data.
a. Test zero offset on isolation amplifier. Place a digital voltmeter between terminals "D" (+) and
"F" (-) on ISOA6. With control power On and no other signal applied, meter should read:
Less than 30 millivolts.
b. Remove wire from input terminal "B" on ISOA6. Connect test jumpers from "G" (+15 volt) to
"A", and from "C" to "F" on ISOA6 and measure the following:
Read +1.00 ±.05 volts from "D" to "F".
PTU should read +275 ±20 amps.
c. Remove jumpers and voltmeter. Reconnect wire to terminal "B".
10. MOTOR TERTIARY OVERCURRENT - ISOA7: mf tert current = 0.0 ac amps
a. Repeat same test procedure used on alternator tertiary current, except substitute ISOA7
instead of ISOA6.
11. ALTERNATOR OUTPUT VOLTS - VMM1: . . . . . . alt output volts = 0.0
(Screen value volts = 200 x analog input volts).
a. Verify that circuit 74C is disconnected at GFR.
b. Disconnect the wires from terminals "A" and "C" on VMM1.
c. Connect digital voltmeter between VMM1 output terminals "D" (+) and "F" (-). With no other
signal applied:
Meter should read less than ±.010 volts.
d. Jumper circuit 71 (battery +) to VMM1 input terminal "A". Jumper circuit 710 (ground) to ter-
minal "C". Attach second digital voltmeter to VMM1 terminal "A" (+) and "C" (-) to measure
actual voltage applied.
e. With control power On and battery voltage applied at terminals "A" and "C", read the follow-
ing at the output voltmeter attached to terminals "D" (+) and "F"(-):
Output voltage = Input voltage ÷ 200 (±.025)
PTU screen should read approximate input voltage.
Example:
If input voltage is 25.25 vdc, output should read .126 ±.025 vdc.
PTU display should read approximately 25 vdc.
E3-28 Statex III Electrical Checkout Procedure 2/02 E03012