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MODEL 1000N
d) Offset adjustment of the amplifier (Z5) when RX = ∞ (open)
• Supply the Model 1000 with 10.5 V DC.
• Connect the voltmeter between the T and D solder pins (the ground connection D can be
made on the spacer of the high voltage switch.)
• Select the 250 V / M Ω range and push down the on/off switch. The beeper must "beep"
approximately every 6 seconds.
• Adjust the potentiometer A101 to obtain a reading of 0 ± 40 µV on the voltmeter.
• Select the 50 V / G Ω range and verify the reading is still 0 ± 200 µV.
• Select the 1000 V / G Ω and adjust the potentiometer A103 to read 0 ± 200 µV on the
voltmeter.
NOTE: Because the two settings are highly sensitive, it is necessary to allow a few seconds
between adjustments in order to obtain a stable reading, especially for the G Ω range.
Never short circuit the terminals at this stage, a memory effect on the input capacitor may
produce an incorrect zero.
e) Adjusting the "1" point on the M Ω scale:
• Select the 500 V / M Ω range and measure 1 M Ω .
• Adjust the potentiometer A4 to read "1" on the M Ω scale.
f) Adjusting the "100" point on the M Ω scale:
• Select the 500 V / M Ω range and measure 100 M Ω .
• Adjust the potentiometer A5 to read "100" on the M Ω scale.
g) Adjusting the "1000" point on the M Ω scale:
• Select the 500 V / M Ω range and measure 1000 M Ω .
• Adjust the potentiometer A102 to read "1000" on the M Ω scale.
NOTE: The adjustment of the potentiometer A5 and A102 are interdependent. It is necessary to
perform these two tests until the two readings are perfect.
h) Adjusting the Ohmmeter:
• Select the 10 mA range on the instrument.
• Measure 100 Ω and adjust the potentiometer A2 to read "100" on the ohms scale.
• Measure 0.1 Ω and adjust A3 to read "0.1" on the ohms scale.
• During this adjustment check the reading on the voltmeter connected between the point T
and D. The value must be positive ( ≅ + 8 mV ). Otherwise, it is necessary to continue
adjusting A3.
• It is necessary to verify the linearity at several locations.
• The deviation should be less than or equal to 1 mV from the theoretical value (or 5%).
• For resistor values under 200 Ω the beeper must be "on" continuously.
4/21/2005
REPAIR AND CALIBRATION MANUAL
12
REV. 7: March 13, 2004
FILE LOCATION: Manuals - Cal. Man - 1000MAN.DOC
CAT. #185.100
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