To install the cable, first make sure the adjustable frequency drive is powered down
and the DC bus is fully discharged.
1.
For D frame size units, follow the procedure in Section 7 for soft charge card removal
and disengage the soft charge card far enough to disconnect the cable plugged into the
MK3.
2.
For all frame sizes, disconnect the cable from the MK3 connector on the soft charge card
and connect one end of the test cable into the MK3.
3.
For D frame size units, reinstall the soft charge card.
4.
For all frame sizes, disconnect connectors MK100 and MK105 on the power card.
5.
For all frame sizes, connect the free end of the test cable into MK105.
6.
For all frame sizes, connect the SCR gate shorting plug into the cable that was removed
from MK100.
When reapplying main input power to the adjustable frequency drive, the soft charge rectifier
provides DC power to the power card. Testing with the use of the gate signal board and the signal
test board can now be carried out without the presence of DC bus voltage.
9.1.2 Signal Test Board (p/n 176F8437)
The signal test board provides access to a va-
riety of signals that can be helpful in trouble-
shooting the adjustable frequency drive.
The signal test board is plugged into power
card connector MK104. Points on the signal
test board can be monitored with or without
the DC bus disabled. In some cases, the ad-
justable frequency drive will need the DC bus
enabled and operating a load to verify some
test signals.
The following is a description of the signals
available on the signal test board. Section 6 of
this manual describes when these tests would
be called for and what the signal should be at
that given test point.
130BX66.10
Figure 9.4: Signal Test Board
9.1.3 Signal Test Board Pin Outs: Description and Voltage Levels
The tables on the following pages list the pins located on the signal test board. For each pin, its
function, description, and voltage levels are provided. Details on performing tests using the test
fixture are provided in Section 6 of this manual. Other than power supply measurements, most of
the signals being measured are made up of waveforms.
Although in some cases, a digital voltmeter can be used to verify the presence of such signals, it
cannot be relied upon to verify that the waveform is correct. An oscilloscope is the instrument
preferred. However, when similar signals are being measured at multiple points, a digital voltmeter
9 Special Test Equipment
High Power Service Manual for VLT
®
FC Series
Adjustable Frequency Drives
9-2
MG.90.L1.22 - VLT
®
is a registered Danfoss trademark
9
Summary of Contents for VLT HVAC FC 100
Page 219: ......