Control Pod Power Led - Janome QMP16SU Manual

Control Pod Power LEDs
Near the top of the control board are two green
LEDs. The control board receives an input of +48V
from the power supply and converts this voltage
into two different voltages levels. The left LED
(closest to the +18Vdc label) indicates that the 18V
power is functioning and the right LED (closest to
the +5Vdc label) indicates that the 5V power is
functioning.
If both LEDs are not on, check the
power cord, power source and power fuse. If one
or both LEDs are not on and the above checked out
OK, the turn off the machine and unplug the power
cord. Disconnect all cables from the control board
except the power cable at the top of the board (the red/black cable). If the LEDs are still not on there may
be an issue with the on-board power supply. If the LEDs both begin working again, this may indicate that
one of the peripherals is shorting out the control board.
Begin plugging the cables back in one at a time (powering off between the connection of each cable) until
you find the cable that is causing the issue. If it is a display cable, then the issue could be the internal
cable, the external cable, or the display itself. You could then try plugging that cable in with the display
disconnected to verify whether it is the cable or the display. If it is one of the other cables, then the
problem may be related to that particular component (needle/ speed encoder or motor driver).
However, if both LEDs are off, check to make sure the black power cord is plugged in and the power switch
is On. A volt meter may be used to verify that there is 48Vdc between the red and black power lines.
If you do not have 48V, then the power supply and attached cables should be inspected for any short
circuits or wires breaking away from connectors on the power side. If the volt meter indicates 48V is
present at the control board power connector and the control board power LEDs are off, then the control
board should be replaced.
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QMP16SU Service Manual