Technical data

Troubleshooting 4
4000 X-Series Oscilloscopes Service Guide 93
Figure 18 Verify power switch operation
• With S101 in the OFF position (switch contacts closed)
you should measure less than 1 ohm of resistance.
• With S101 in the ON position (switch contacts open)
you should measure infinite resistance.
If you do not measure these two values, there is
something wrong with the power switch (S101 on the line
filter assembly), and you need to replace the line filter
assembly.
If the power switch is good, and the AC input to the
power supply is good, but the 13 V bulk power is not
being properly supplied, it is likely that the power supply
is bad. To rule out a bad DC supply cable, see “To check
the power supply DC output” on page 94.