User`s guide

8-2
8.3 Troubleshooting the Power Supply
WARNING !
Potentially lethal voltages exist within the DCM-200
enclosure. Only qualified service personnel should be
permitted access.
WARNING
To avoid damage to the electronics caused by static discharge, ensure that
proper ESD control procedures are followed.
See Chapter-11 for additional information.
Whenever trouble-shooting is performed on any type of electronic device, the most
logical place to start is with the power supply section. It may be helpful to refer to the
block diagrams in Chapter-3 when working with the power supply. A handheld voltmeter
is required for executing the service steps detailed below.
1) Check if the green LED labeled ‘AC PWR’ on the main power supply board is
illuminated. If so, then skip ahead to step # 5.
2) Unscrew the two Phillips screws that hold the metal shield plate in position. Carefully
remove the metal shield plate, keeping in mind that live AC mains power is likely to
be present along with the potential for a lethal shock hazard.
3) With the voltmeter in the “AC Volts” test mode, verify that the correct AC line voltage
is present at the two left-most terminals of the terminal block. Depending on the
installation site, this voltage may in the range of 90 to 277 volts AC.
4) Often times it is possible to check the condition of fuses by performing a simple
visual inspection for black burn marks within the glass tube. If this is not the case
then each fuse can be checked with the voltmeter while in the “AC Volts” test mode.
A good fuse will have a voltage reading very close to zero, while an open fuse show
the entire AC line voltage across it.
Blown fuses should only be replaced with components of the same type and rating.
Fuses must only be replaced while the AC mains power is completely removed. If fuses
continue to blow then there is likely to be an overload condition exists somewhere within
the DCM-200.
For power supply boards built prior to 2006 (stock number 1001-0302) it should also be
verified that the fuses are installed into the correct positions and that the quantity of
fuses is correct. Although there are three fuse positions available on the power supply
board, it is never permitted that all three should be installed at the same time. Table 2-1
in Chapter-2 lists the correct fuse installation verses AC input voltage range.
For power supply boards built in 2006 and later (stock number 1001-0310) verify that the