Tweco HMC-410 - Manual (Page 34)

HMC-410
2-16 July 27, 2005
Power Supply/Motor Control PCB Assembly
(Refer to Figure 2-7)
The Power Supply/Motor Control PCB Assembly (PS/MC
Board) has two functions. It provides the various low
voltage control voltages used by the solid state circuitry
throughout the HMC-410. It also translates control signals
from the controller board into power for the motor.
The power supply section of the board utilizes the off
board transformer to divide the line voltage down to the
voltage levels used by the circuitry in the system. The
rough functionality of this circuitry can be performed by
visually inspecting the LEDs on the board. If the LED is
lit, then the voltage is at least approximately what it should
be. In order to verify the exact voltages, a meter can be
used on the following test points:
HI LO Expected Reading Status LED
TP1 TP2 –15 VDC (± .05 VDC) CR3
TP3 TP2 +5 VDC (± .5 VDC) CR7
TP4 TP2 +15 VDC 1 (± .05 VDC) CR2
TP5 TP7 +15 VDC 2 (± .5 VDC) CR9
TP6 TP7 +15 VDC UNREG CR8
(+25 to +35 VDC)
TP7 TP9 +12 VDC (±.5 VDC) CR17
NOTE
These measurements and repairs should be
performed only by a qualified electrical
technician.
The motor control circuitry drives the DC motor which
feeds the filler metal used in the MIG process. There are
various protection circuits which will disable the motor
control circuitry should it detect an excessive load on the
motor or control circuitry. Some of these protections
require that the panel’s power be cycled to reset them.
Also, the fuse F5 could blow should the motor current
exceed its limits. Should these shutdowns continuously
set, check that the filler metal can freely feed. If it is not
impeded, verify that the cabling is not damaged. The PS/
MC board interconnects to the transformer, the controller
board, and the interface/suppressor board.
CR9
Art # A-04363
Figure 2-7: Power Supply/Motor Control PCB Assembly