Technical data

92 4000 X-Series Oscilloscopes Service Guide
4 Troubleshooting
• If there is no AC power at J1 of the power supply,
there is something wrong with the AC mains section of
the line filter assembly, and you need to replace the
line filter assembly.
• If there is AC power at J1 of the power supply, but the
instrument still will not power ON when the power
switch (S101) is in the ON position, go to “To check the
power switch” on page 92.
To check the power switch
This procedure verifies the operation of the power switch
(S101) on the line filter board assembly.
1 Follow the instructions in “To prepare for internal
assembly troubleshooting” on page 83.
2 With the power cord disconnected, verify the operation of
the power switch (S101) using a DMM in the resistance
measurement mode and a set of probes.
a Remove the “remote on/off” cable from connector J107
on the line filter board.
b Place the DMM probes on pins 1 and 2 of J107.