Tweco HMC-410 - Manual (Page 66)

HMC-410
5-4 July 27, 2005
H. Gas valve is stuck on or off.
1. Interconnecting cable between control panel and
feedhead may have a bad connection or short
circuit.
a. Repair or replace interconnecting cable.
2. Gas valve control relay failure on controller board.
a. Check relay control signal using diagnostic test
#50. Replace relay or controller board if bad.
3. Gas valve failure.
a. Replace valve.
4. 24 VAC failure.
a. Check 24 VAC out of transformer by checking
+15 VDC UNREG LED on PS/MC board.
Replace transformer if bad.
I. Front panel does not function.
1. Unit does not power up
a. Verify unit powers up. Verify PS/MC board
voltages are OK by checking the power LEDs.
2. Interconnect between C/D board and controller
board. Interconnect between controller board and
PS/MC board.
a. Verify cables are good. Repair or replace if de-
fective.
3. Defective controller board.
a. Replace controller board if bad. One easy way
to check if the controller board is working
without seeing the front panel is to select
diagnostics test #49 and #48 alternatively. If
the relay can be heard turning on and off (it is
very quiet but audible), the board can be
presumed to be functioning. Replace if not
functioning.
4. Defective C/D board.
a. Replace C/D board.
J. DIP switch functions do not work.
1. Bad DIP switch.
a. Replace controller board.
2. Controller board failure.
a. Replace controller board.
3. Incorrectly installed cable, switches.
a. Verify cables installed on controller board
correctly. Verify option switches are in the
correct position.
K. Schedule program data lost or corrupted after
controller power down. Also, if OFF is displayed
for Schedule Number.
1. Bad memory chip.
a. Replace controller board.
L. Control panel fails to respond to control input or
responds unusually.
1. Line voltage drop or spikes on the AC power line.
a. Isolate controller AC power lines.
2. EMI radiation from equipment in the vicinity of
the controller.
a. Remove suspect equipment from the vicinity.
Reduce interconnecting cable lengths to a
minimum. Be sure all weld system equipment
is properly grounded to earth ground.
3. Controller board failure.
a. Replace controller board.
4. Unusual weld starts or transients from the power
source.
a. Check power source for malfunctions.
M. The controller allows the weld cycle to progress
through the run in segment and terminates the
cycle.
1. Power source is not providing an arc established
signal.
a. Check power source manual for service
information.
2. Controller does not recognize the arc established
signal provided by the power source, may be a
bad controller board channel or interconnect to I/
S board.
a. Replace controller board, I/S board, or
controller to I/S ribbon cable.
3. Difficulty starting arc due to dirty work or improper
programming.
a. Reprogram run in parameters, lengthen time,
increase arc voltage and/or wire feed speed.