Global Specialties PB-505 - Manual - Manual (Page 14)

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the logic indicator +5/+V operating voltage switch to +V; indicator display should remain
the same, regardless of the setting of the 1.3-15 volts +V supply.
By using an ohmmeter, you can check the potentiometers. To do so, select an
appropriate range for measuring 10K and connect the ohmmeter leads to R1-1 and R1-
2. With R1 rotated fully counterclockwise a reading of zero ohms should be observed.
As the potentiometer is rotated clockwise, the resistance reading will be seen to
increase linearly up to 10K ±20%. Now move the ohmmeter lead from R1-1 to R1-3;
with R1 fully clockwise the ohmmeter will read zero ohms, and the resistance will
increase linearly to the full value noted previously as the potentiometer is rotated
counterclockwise. Select an ohmmeter range appropriate for IK and repeat these steps
on R2 to verify its function.
To test SPDT switch S9, put S9 in the up position and connect and ohmmeter to S9-1
and S9-2. The ohmmeter should read zero ohms. When the switch is brought to the
down position, an open circuit should be indicated. Move the ohmmeter lead from S9-1
to S9-3 and observe a short circuit with S9 down, and an open with S9 up. These steps
can be repeated on S10 to test its functions.
To test the logic probe, connect a wire from Vcc to +5 terminal. Set mem/pulse switch to
pulse and TTL/CMOS switch to TTL. Connect a wire from input to +V terminal. Connect
the multimeter between GND and +V. Turn the +V pot fully counter-clockwise, read
approx. 1.2V on the meter. Slowly turn the +V pot until the HI LED lights. Read approx.
2.4V on the meter. Set pulse/mem switch to mem. Touch input lead to ground. Observe
low LED lighting and pulse LED lighting and staying on. Move pulse/ mem switch to
mem and observe pulse LED going out. Move TTL/CMOS switch to CMOS, reconnect
input lead to the +V terminal. With the +V pot fully counter clockwise, slowly turn the +V
pot clockwise until the low LED goes out. Read approx. 1.6 volts on the DMM. Continue
turning the +V pot until the HI LED lights read approx. 3.5 volts on the DMM.
To test the BCD to 7 segment displays, jumper together pins 1A, IB, and 1C. Connect a
jumper wire from these points to ground. Connect a second jumper wire from position
10 to +5V. Observe a number 8 showing on the display. Repeat this test for display
number.