General Maintenance
Detailed Troubleshooting Procedures
The following tests should be run as indicated in the
Symptom and Causes
table.
(See Table 4 on page 23.). The procedures check for speci
fi
c problems or will help
you isolate a problem to a board. You can run them at any time for informational
purposes but if you do not run the procedures in the correct context, then the
fi
nal
recommendation identifying a root cause might be suspect.
General Checks
Check that the power cord is installed.
1.
Verify that the power cord is connected.
2.
Check that the monitor cable is connected on both ends and that the screws
are holding it securely.
3.
Check that all internal cables are correctly connected and seated.
4.
Check for any discolored or burned components.
Fan Failures
This instrument contains four fans, They are controlled by both hardware and
software. Hardware controls the fans to a certain speed, but software sets the
speed target as a function of the temperature measured on a variety of temperature
sensors.
If a fan fails, its corresponding LED on the Main board lights.
Fan 1 fails: LED DS12 lights
Fan 2 fails: LED DS11 lights
Fan 3 fails: LED DS23 lights
Fan 4 fails: LED DS22 lights
A fan failure is sensed through tachometer feedback; a fault will be asserted if
the fan is not connected, is stalled, or if the tachometer feedback line is not
working correctly.
If one fan fails, the control circuit will increase the voltage to the 13.5 V max
level, causing the remaining fan to run at maximum speed.
The normal voltage to drive the fans (pin 1) varies from about 6 V to
13.5 V depending on temperature and the options installed on the instrument.
If a fan is not spinning, measure the voltage on pin 1 of the connector on that
fan. If the voltage is near 13 V, then replace the fan. If the voltage is not above
10 V, then replace the main board.
26
WVR7200 Waveform Rasterizer Service Manual
