Service manual

5 125
Power Supply Troubleshooting
FIND OUT WHY THE FAN IS NOT ROTATING
5. Power Supply Troubleshooting
FIND OUT WHY THE FAN IS NOT ROTATING
If the fan is not rotating, the problem may be in the A40 pre-regulator, the A50 DC-DC
Converter or the fan.
1. Check the Line Voltage, Selector Switch Setting, and Fuse
Check the main power line cord, line fuse, and actual line voltage to see that they are all
correct.
Figure 5-6 shows how to remove the line fuse, using a small flat-bladed
screwdriver to pry off the fuse holder. For more information about the line cord and line
fuse, see the Power Requirements in Appendix C.
Figure 5-6 Removing Line Fuse
2. Check the A40 Pre-Regulator
1. Turn the analyzer power off.
2. Disconnect the cable from the A50S2. The A50S2 location is shown in Figure 5-7.
3. Turn the analyzer power on.
4. Check the voltage between pin 1 and pin 6(GND) of the cable within +22.0 V to +27.0
V using a voltmeter with a small probe.
• If the voltmeter reading is not within these limits, replace the A40 pre-regulator.
• If the voltmeter reading is within these limits, the A40 pre-regulator is verified.
Turn the analyzer power off and reconnect the cable to the A50S2. Then continue
with Check the A50 SHUTDOWN LED.