English
Page 4
5.
Return the AC Calibrator to OPER. The DMM should
read between 28.3 and 31.8V dc
6.
Return the UUT to the scope output and set the level
sine to 1V rms 160 MHz. The DMM should read between 0.9
and 1.12V dc. Increase the frequency to 450 MHZ. The DMM
should read between 0.70 and 1.41V dc.
Troubleshooting
Isolate a problem to the probe by verifying the operation of
the probe’s input source and output DMM. Most probe
malfunctions are caused by the failure of diodes CR1 or
CR2. Suspect CR1 if there is no output when an input is
applied to the probe. Excessive linearity error may be due to
the failure of CR2. Use a continuity test for in-circuit diode
testing. If the diodes are good, check the input and output
connections to the printed circuit board and the continuity of
the output cable.
CAUTION
The diodes have glass bodies; care should be taken to avoid
stressing them, particularly when preparing the leads. The diodes
are also subject to failure from overheating. When soldering, hold
the lead near the diode body with a pair of needle nose pliers.
Avoid excessive heat.
Probe Disassembly
Use the following procedure to access the probe’s internal
components, including the calibration adjustment R2:
1.
Unscrew the bend relief and slide it away from the
probe.
2.
Lift off the probe cover. R2 is exposed.
3.
Remove the probe tip by carefully grasping the tip with a
pair of pliers and drawing it out of the front of the probe.
4.
Unscrew the ground lead from the probe body.
5.
Lift the rear of the printed circuit board slightly and pull it
firmly away from the probe tip.
6.
To reassemble the probe, logically reverse this
procedure. Make sure that the gold pin on the front of the
printed circuit board centers properly in the tip and that the
ground-lead nut is aligned with the hole in the probe body.
Cleaning
Use a soft cloth dampened in a mild solution of detergent
and water to clean the 85RF. Do not use solvents.
85RF PARTS LIST
DESCRIPTION
PART
NO.
C1
Cap, Ceramic Chip, 220 pF
758078
CR1 Diode,
Germanium
629261
CR2 Diode,
Silicon
639922
R1 Resistor,
cf,
220k
348953
R2 Resistor,
Var,
500k
574624
R3 Resistor,
cf,
1.3M
442558
Body,
Probe
606988
Cover,
Probe
581751
Tip,
Probe
607267
Wire,
Ground
Assy
607291
Decal,
Probe
585842
Contact,
Ground
586560
Contact,
Twist
Pin
294991
Tip,
Insulated
583682
Tip,
IC
583674
www.
.com
1.800.561.8187