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Troubleshooting Procedures
WFM 90 and WFM 91 Service Manual
6–33
NOTE. If the jumper wires will not stay securely attached to the battery connector
pins, you will need to remove the instrument bottom case to obtain access to the
battery connector pins on the Bottom board. Refer to Bottom Cover on
page 6–23.
4. Attach the voltmeter across test resistor #1 in Figure 6–15.
5. Connect the AC adapter to the WFM 90 or WFM 91 Handheld Waveform,
Vector, Picture, and Audio Monitor.
6. Check for a voltage reading of +8 to +9 VDC on the voltmeter with the
instrument turned on or off.
7. If the voltage reading in the previous step was correct, replace the batteries.
If the voltage reading was incorrect, replace the Bottom board.
Use the following procedure to determine if the battery charger circuit is
operating properly:
1. Remove the AC adapter from the WFM 90 or WFM 91 Handheld Wave-
form, Vector, Picture, and Audio Monitor.
2. Remove the battery cover and any installed batteries from the instrument.
See Batteries on page 6–21.
3. Use three jumper wires to connect a 30 W, 3 W resistor to the battery
connector pins. See Figure 6–16.
Jumper wires (3)
Battery connector
+
–
Test resistor
Figure 6–16: Testing the battery charging circuit – WFM 90 SN B011363 and above;
WFM 91 SN B010471 and above
WFM 90 SN B011363
and Above;
WFM 91 SN B010471
and Above