TROUBLESHOOTING & REPAIR
F-70 F-70
RANGER 305D
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WELD CONTROL BOARD PWM GATE SIGNAL TEST (continued)TEST PROCEDURE
1. Perform the Case Cover Removal
Procedure.
2. Unplug any device that may be attached to
either the 6 pin or the 14 pin Amphenol
receptacles.
3. Place the idle switch in the “HIGH IDLE”
position.
4. Place the mode switch in the “CC-STICK”
position.
5. Place the Weld terminals switch in the
“WELD TERMINALS ON” position.
6. Start the engine and let it run and stabilize
at high idle RPM.
7. Locate plug P3 on the control PC board.
See Control Inner-Connection diagram.
8. Use the frequency counter to test for 20kHz
PWM gate signal between leads #23+ (P3-
10) and #25- (P3-9).
9. If the 20KHz gate signal is present, place
the weld terminals switch in th e”REMOTE-
LYCONTROLLED” position. Thegate sig-
nal should turn off.
10. If the 20 KHz gate signal responds as
described above, this test is complete.
11. If there is no 20 KHz gate signal, test for the
presents of 80 to 100 VDC, at leads 13+
(P3-8) to 14- (P3-16) of the weld control PC
board.
12. If voltage isvery low or not present, check
leads #13 and #14 for faulty or damaged
wiring or connections between the control
PC board and the chopper module.
13. Test for 80 to 100 VDC at the terminals
where the #13 and #14 leads connect to the
chopper module. See the wiring diagram. If
there is no voltage at the chopper module,
perform the chopper module function test.
14. If the 80 to 100 VDC supply voltage is pre-
sent at the weld control PC board, but there
is no PWM gate signal, check the voltage
between leads #2+ (P1-4) and #4 (P1-3).
See figure #1
The voltage should be about 0 VDC.
15. If about 5 VDC is detected, the welding ter-
minal control circuit is open. Check for
damaged leads for faulty connections at
leads #2 and #4; also check for a defective
welding terminal switch. See the wiring dia-
gram.
16. If the PWM signal remains after the welding
terminal switch has been placed in the
“REMOTELYCONTROLLED” position,
check the voltage between leads #2+ (P1-
4) and #4- (P1-3) at the control PC board.
17. If the voltage reads 0 or very near 0, Check
for damaged insulation at leads #2 and #4,
also check for a shorted welding terminal
switch, or damaged or contaminated
Amphenol receptacle. See the wiring dia-
gram.
18. If the above wiring and components are
undamaged and functioning properly,the
control PC board is defective and should be
replaced.
19. If the voltage reads about 5 VDC, and the
PWM signal remains, the control PC board
is defective and should be replaced.
20. Perform the Case Cover Replacement
Procedure.