TroubleshootingProcedures
6-40 WFM90D and WFM91D Service Manual
Battery-FaultAnalysis
NOTE. If the instrument functions properlywhen pow eredby the AC adapter, but
thereare battery or battery charging problems, use the following procedure. If
thereare no battery problems or if the instrument does not function properly
with the AC adapter,proceed to Low-Voltage Power Supply on page 6--42.
Use the following procedureto determine if the battery charger circuit is
operating properly:
1. Remove the AC adapter from the WFM90D or WFM91D.
2. Remove the batterycover and any installed batteries from the instrument.
SeeBatteries on page 6--28.
3. Use three jumperwires to connect a 30 Ω, 3 W resistor to the battery
connectorpins, as shown in Figure 6--19.
Jumperwires (3)
Batteryconnector

+

--

Testresistor
Figure6 -19: Testing the battery charging circuit
NOTE. If the jumper wires will not stay securelyattached to the battery connector
pins, removethe instrument bottom case to obtain access to the battery
connector pins on theBottom board. Refer to Bottom Cover on page 6--31.
4. Attach the voltmeteracross the test resistor shown in Figure 6--19.
5. Connect the AC adapter to the WFM90D or WFM91D.