Technical data

98 4000 X-Series Oscilloscopes Service Guide
4 Troubleshooting
5 If the fan voltage is approximately +9 Vdc at room
temperature, replace the fan. If the fan voltage is not
approximately +9 Vdc, replace the system board.
The proper voltage range depending on temperature is
between +7.9 Vdc to +12.8 Vdc.
Figure 19 Location of the Fan Connector