Fluke 78 - RPM80 Inductive Pickup Test (Optional Accessory)

78
Service Manual
3-14
3-24. RPM80 Inductive Pickup Test (Optional Accessory)
To test the RPM-80 inductive pickup, a triangle wave from a Function Generator will
simulate automobile spark plug signals on a loop of wire containing a 10-ohm resistor.
The pickup will be clamped to the wire, and output voltage from the pickup will be
monitored by an oscilloscope.
To test the RPM80 Inductive Pickup, proceed as follows, referring to Figures 3-4 and 3-
5 as necessary:
1. Solder a 10-inch piece of 14 or 16-AWG wire to one end of the 10-ohm resistor.
2. Connect the other end of the resistor to the LOW and the wire to the HIGH of the
binding-post-to-BNC adapter. Connect the adapter to the output of the Function
Generator. See Figure 3-4.
3. Connect a 10X-scope probe from channel 2 (dc-coupled) of the oscilloscope across
the 10-ohm resistor (not across the Function Generator output).
4. Clamp the inductive pickup to the wire loop as shown in Figure 3-4. Make sure that
the jaws of the inductive pickup are closed completely, and that the side of the
pickup which says "SPARK PLUG" points toward the HIGH output of the Function
Generator.
5. Connect a 10X-scope probe from channel 1 (dc-coupled) of the oscilloscope across
the output of the inductive pickup.
6. Set up the Function Generator as follows:
FREQ RANGE Hz 2M
FREQUENCY 0.600 MHz
ATTENUATION None
MOD/SWEEP PERIOD s .1 (PM5133)
MOD/SWEEP PERIOD s 10 ms (PM5134)
MODE SINGLE
WAVEFORM Triangle
CONT Out
LIN In
DUTY CYCLE Out
OUTPUT 50 Ohms
PERIOD Halfway (PM5133)
PERIOD x1 (PM5134)
START PHASE π/2
DC OFFSET In
7. Set channel 2 of the oscilloscope for 0.5 V/DIV at 0.5 µs/DIV time base.
8. Trigger channel 2 on the triangle waveform. Adjust the amplitude of the Function
Generator for an output of 3 V peak. See Figure 3-5.
9. Set channel 1 of the oscilloscope for 1.0 V/DIV at 5 ms/DIV time base.
10. Trigger channel 1 on the inductive pickup waveform. Adjust the Function Generator
PERIOD for a 10 ms repetition rate.
11. Check that the peak voltage is greater than 5.5 V and decays to less than 1.0 V
between pulses. See Figure 3-5.
12. Turn the inductive pickup so that "SPARK PLUG" points toward the LOW output of
the Function Generator. Check that the waveform is less than 2 V.