85RF Fluke Electronics, 85RF Datasheet - Page 84
85RF
Manufacturer Part Number
85RF
Description
PROBE HIGH FREQ 500MHZ
Manufacturer
Fluke Electronics
Type
High Frequencyr
Specifications of 85RF
Impedance
10M Ohm
Voltage - Max
30VRMS, 200VDC
Lead Free Status / RoHS Status
Lead free by exemption / RoHS compliant by exemption
Ratings
-
Current Rating
-
Color
-
Termination
-
Wire Insulation Material
-
Cable Length
-
Other names
532457
8062A
Instruction Manual
4-22
Power On/Microcomputer and
Display Test
Power Supply
No display
Missing LCD segments
All LCD segments stay on
Entire display is dim
Some display segments are
dim or ghosting
VDD (voltage between
One way to check the input circuitry is to attach a high impedance
(>1000 M ) DMM at the input of the 8062A a/d converter, U3-6.
You can do a lot of troubleshooting without the LCD and
microcomputer pcb installed. Although there will be no display and the
a/d converter will not work, the power supplies still work so you can
check the input circuitry, the diode test and ohms sources, and the ac
converter. Another advantage is that you gain access to all the pins on
U3 without having to turn the main pcb over.
You can troubleshoot the input circuitry with U3 removed (be sure to
disconnect the battery before removing U3). Since U3 controls the
power supply, removing U3 will cause the ac converter and diode test
source to stop working. However, it will also eliminate any power
supply leakages that might be affecting the input circuitry. Since the
input protection, input divider and ohms reference resistors, amps
protection, current shunts, and a/d input circuits consist of passive
components (refer to the schematic in Chapter 7) you can check them
without having U3 installed.
TP7 and common)
Test and Symptom
5.2 0.12V
Table 4-6. Troubleshooting Guide
Dead battery, battery connections,
J4, power supply circuitry.
Microcomputer connector, U5, U3,
pcb lands open.
Low battery, power supply low,
display interconnect.
Display interconnect, contamination
on pcb connector or LCD.
U3, Q1, VR1
Display interconnect.
Possible Cause/Suggestions