Nelson ALPHA 850 - Page 57

9 Repairs Page 52
Stud welding unit operating manual Date: July 2021
ALPHA 850 07.2021 / EN Rev.: A
Fault: Welding
Features:
• ALPHA 850 is switched on
• “System voltage" LED lights up
• Fan runs
• “Fault” multi-function LED lights up white
• Gun works at start trigger (air release)
• no weld
No.
Possible
cause
What is to be
tested or how?
Test
result
Test result achieved?
yes no
1
No contact detection
of ALPHA 850
Does the “Contact” LED
light up upon contact of
the stud and workpiece?
YES No. 8 No. 2
2
No earth connection
Check the earth
connection
OK No. 4 No. 3
3
No earth connection
Connect the earth plug
and earth clamps
OK ready No. 4
4
Weld point not
conductive
Clean the weld point
OK ready No. 5
5
Contact detection
defective
Check the PCB plug X4
1)
OK No. 7 No. 6
6 Connection X4
1)
open Make the connection OK ready No. 7
7
PCB defective
Replace the PCB *)
OK ready No. 14
8 Pilot current fault Does the arc ignite? YES No. 9 No. 12
9
Arc break or short
circuit
Lift set incorrectly?
YES No. 10 No. 14
10 Lift error Set lift OK ready No. 11
11
No phase L2
Check the transformer
connection on the power
switch
OK ready No. 14
12
Cabling error
Pilot current choke
connected wrong?
YES No. 13 No. 14
13
Pilot current choke
connected wrong?
Connect the pilot current
choke correctly
OK ready No. 14
14
Shut down ALPHA 850
Notify Tucker service!
Tasks indicated with *) must be done only by electro-technical personnel!
1)
The arrangement of plug connections X4 on the internal control card can be found in the illustration
on page 54.