Tweco SC10 - Manual (Page 35)

Manual 0-2479 5-5 CUSTOMER/OPERATOR SERVICE
D. Lifter Motor and Cable Tests
1. Remove cable from torch lifter assembly. Mea-
sure for + (up) or - (down) about 20v with meter
(+) on pin 1 and negative (-) on pin 2 of the cable
when TORCH UP or TORCH DOWN is pressed.
TORCH UP or TORCH DOWN indicator not ON
may indicate no output to motor however a
shorted motor or cable can prevent the indicator
from coming ON. If indicators are correct, remove
lifter assembly cover and check wiring to motor.
Also check for binding of the torch lifter assem-
bly slide.
NOTE
The mounting bolts attaching the torch lead sup-
port bracket to the Torch Lifter Assembly can bind
if the mounting bolts are too long.
2. If no voltage is seen in above step 1 repeat the
measurement at pins J43-1 and J43-2, if no volt-
age at J43 check at J10-1 and J10-2. If no voltage
at J10, Standoff Control PC Board is faulty other-
wise the J10 harness or motor cable is open.
If Torch moves up but not down. TORCH DOWN
indicator will not come ON.
a. Remove motor cable from J43 and check for
continuity between pins J43-7 and J43-8. If cor-
rect (less than 500 ohms) Standoff Control As-
sembly is faulty. If over 500 ohms possible
causes are:
• Open motor cable (pins J43-7 or J43-8)
• Open connection between motor cable con-
nector and micro-switch in the torch lifter
assembly
• Faulty microswitch
• Switch being held open, possible sticking
slide.
Torch moves up and down manually.
Check for proper START signal to Standoff Control
Assembly PC Board. If START indicator, D79, comes
ON, START signal is present, Standoff Control As-
sembly is faulty. START signal comes from the Re-
mote Control, RC6010, at J7-13.
NOTE
Refer to Appendix 3 and Appendiv 4 for schematic
of START signal circuits.
If START indicator , D79, does not come ON, jumper
J11-3 to J11-4.
CAUTION
Torch may start.
If START indicator , D79, comes ON and torch finds
height and pilot starts then problem is in the START
signal input to the Standoff Control Assembly. Check
the CNC cable input or the internal ribbon cable be-
tween the Standoff Control Assembly and the Remote
Control Assembly (RC6010) if used.
E. Tip-On-Work Micro-Switch Tests
To test the micro-switch, remove the motor cable from
J43 on the back of the Standoff Control Assembly and
with the torch not on the work measure continuity
between pins J43-7 and J43-8 of the cable. Then lift
up on the torch. The small slide should move freely
and come up about 1/2 inch and pins J43-7 and J43-
8 should measure open circuit. If correct then the
Standoff Control Assembly is faulty.
F. OK-To-Move Signal Tests
Check for internal indicator, OK PS indicator D82
comes ON when arc starts.
If indicator is OFF, jumper J8-5 to J8-6. If OK PS indi-
cator comes ON then the OK-To-Move signal is miss-
ing to the Standoff Control Assembly.
NOTE
Refer to Appendix 5 for schematic of OK-To-Move
circuit.
If indicator is still OFF, then the Standoff Control As-
sembly is faulty.
If indicator OK PS comes ON when arc starts, set
PIERCE DELAY to minimum and check for D37 PS
OUT indicator for an ON condition.
If indicator D37 does not come ON the Standoff Con-
trol Assembly is faulty.
If indicator D37 comes ON, then the Standoff Con-
trol Assembly is okay, go to System Troubleshooting
Section in the Power Supply Service Manual for the
OK-To-Move Test Procedure.
G. Arc Voltage Tests
If Arc Voltage display reads near zero, voltage signal
is not present to the Standoff Control Assembly. Mea-
sure voltage at J8-3(negative) and J8-4(positive).
Should be between 6 to 12 volts when cutting (9 volts
when cutting equals minus 150 arc volts).
If correct the Standoff Control Assembly is faulty. If
no voltage refer to the System Troubleshooting in the
Power Supply Service Manual.