Tweco TD-750 Cutting Systems User Manual

Page 21

Manual 0-2475

SERVICE

NOTE

Connector J1 must be connected to the Arc Starter
PC Board.

• If red LED is ON proceed to Step 15.

• If red LED is OFF proceed to Step 6

6. Remove connector J1 from the Arc Starter PC Board

and reconnect making a good connection.

7. On the Arc Starter PC Board check the red LED indica-

tor.

• If red LED is ON proceed to Step 15.

• If red LED is OFF proceed to Step 8

8. Remove connector J1 from the Arc Starter PC Board.

9. Measure for 24 VAC between J1-1 and J1-3 on the con-

nector.

• If 24 VAC is at the connector, Arc Starter PC Board

is defective.

• If 24 VAC is not present at J1 proceed to Step 10.

10. Place the RUN/SET/PURGE switch on the Power

Supply to the RUN position.

11. Place the main power switch on front panel of the

Power Supply to OFF.

12. Remove the Torch Leads Extension Assembly from

the bulkhead connection at the front panel of the
Power Supply.

13. Turn the main power switch on the front of the Power

Supply to ON.

14. Check for 24 VAC between pins 5 and 8 of the Torch

Control connector (J14) at the Power Supply bulkhead.

NOTE

Refer to the Power Supply Operating and Service
manuals for more details.

• If not present, problem is in the Power Supply.

Check the 24 VAC circuit Fuse F3 (1A, 250V) lo-
cated on a panel above the Main Transformer on
the right side of the Power Supply (facing the front
of unit). Check the fuse and replace as necessary.

If the Fuse (F3) blows again on power up or when
you try to start the pilot, Arc Starter PC Board is
defective.

If Fuse (F3) blows once cutting starts there may
be a short in the OK-To-Move circuit. The same
24 VAC is used for OK-To-Move if selected by SW5

on the Power Supply Logic PC Board. Refer to
the Power Supply Operating Manual for OK-To-
Move options.

Note

If the Remote Control RC6010 is used the 24 VAC
OK-To-Move should not be selected at SW5 in the
Remote Control.

• If present, check for open in Torch Leads Extension

Assembly signal wires.

A-00809

Signal Connector

Torch (+)

Coolant Return

Secondary

Gas

Torch (-)

Figure 4-1 Signal Connector Pin Location

15. If the Arc Starter PC Board 24 VAC red LED was ON

from the test in Step 5 or 9, place RUN/SET/PURGE
to RUN position.

16. Press start after pre-flow and go through start se-

quence. PILOT and DC LEDs are ON. When the
Power Supply is activated and the DC and PILOT
LED's are ON, there should be greater than 220 VDC
between the torch tip (+) and electrode (-).

WARNING

High voltage (300-400vdc) is present in Arc Starter
Box.

17. Measure between E1(+) and E2 (-) on the Arc Starter

PC Board.

• If voltage more than 220 VDC is present Arc Starter

PC Board is defective.

NOTE

A dirty or incorrect gap in spark gap could cause
the same problem. Gap should be 0.015 +/- 0.001"
and is not adjustable.