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Bird Model 4391A Power Analyst
24
Disassembly
Front Panel
Removal
1. Disconnect AC power from the instrument.
2. Remove the six screws that secure the front panel to the
Main PCB supports (Figure 18, page 25, item 1).
3. Remove the two screws and lock washers that secure the
front panel at the bottom of the housing (item 2).
4. Remove the two screws and lock washers that secure the
front panel at the back of the housing (item 3).
Display
indicates “0”
Power
Element wiper not
contacting the element
Readjust the element wiper to
make good contact (page 21).
Defective Plug-in
Element
Replace Plug-In Element.
Defect on Data
Acquisition PC board
assembly
Replace the PC board
assembly (attached to line
section). Refer to page 27 and
either page 31 or page 32.
One segment of
a display doesn’t
light
Defective Display Replace the display.
All decimal
points stay lit
Low charge on the
batteries
Recharge the batteries.
Defective circuit
component
Replace the Main circuit board
assembly. Refer to page 25.
Same segment
on all displays
doesn’t light
Defective circuit
component
Replace the Main circuit board
assembly. Refer to page 25.
One or more
keys do not
function
Defect on Main PC board Replace the Main circuit board
assembly.
PROBLEM POSSIBLE CAUSE REMEDY
WARNING
Be sure that the power cable is unplugged before opening
the wattmeter case. The power supply capacitor, C1, can
retain a dangerous charge that must be removed before
touching. Always have another person standing by who is
trained in electric shock first aid.
CAUTION
This instrument contains static sensitive electronic
components. Before opening or servicing the unit, make
sure that you understand and practice electrostatic
discharge component handling. Failure to comply may
result in permanent damage to sensitive components.