Verify the adequacy of the power supply.
Line voltage must be 109 to 133vac at 60 Hz or 109 to 132vac at 50 Hz.
If the line voltage is not within tolerance you must replace the voltage source.
(a) Remove the front cover by removing the two screws on the top and
the two screws on the bottom of the front cover. See figure 1-8.
Figure 1-8. Multimeter connections for power supply adequacy test.