Fluke 8062A, Instruction Manual

Page: 86 / 124

8062A
Instruction Manual
4-24
Table 4-6. Troubleshooting Guide (cont)
Test and Symptom Possible Cause/Suggestions
Voltage Test - DC (cont)
High impedance dc readings
0.00, normal dc
readings correct
R1
DC readings incorrect for
all ranges
Leakage from pcb, U3-6/7,
contamination
DC readings correct for
200 mV, 2V

incorrect
for 20V, 200V, 1000V
Input divider or input divider switches,
R2
Voltage Test - AC
DC reading correct,
ac readings incorrect
Switches S3D, S3B
Check power supply connections
J13 Vss
J7 Com
J12 Vdd
Resistance Test
All ranges incorrect Ohms source voltage inadequate -
using a voltmeter in the 2V or 20V
range, measure ohms source voltage
between TP11 and common. Refer to
Table 4-7 for correct values.
Q3, Q4, RT1, R2, R1, Z5
All ranges incorrect CR1 not supplying enough current
(particularly if 200
Ω
range noisy).
Select diode test, connect an external
1 k
Ω
resistor across the inputs and
measure the voltage drop across the
resistor - should be approximately 1V
(
±
10%).
CR1 supplying proper current,
but reading off
Check values of the reference
resistors for the range not working.
Check voltage drops across the
known and unknown resistors and
make sure the ratio works properly.