AEMC 1000N Calibration Manual page 18

MODEL 1000N
• Supply voltage to the circuits with a voltage level of 12 V while monitoring the current with an
ammeter connected in series. Normal consumption is typically less than 50 mA.
• Excessive power consumption may be attributed to a short circuit at (Q1), or to defects in the
integrated circuits identified as (Z1), (Z4), and (Z8). Because these circuits are situated upon
mountings, they should be disconnected one by one until proper power consumption is
obtained.
• If none of the previously cited circuits is defective, it is advisable to check the capacitors
identified as (C24) and (C25) for probable leakage or short-circuiting.
• When the proper power consumption has been obtained, check the + 5 V and the - 5 V
levels, as well as the voltage level of diode (CR1) (+ 2.5 V).
• Disconnect the power source and reconnect the primary of the transformer.
2) Checking the Zero Setting for 1000 V / G Ω :
• Reassemble the three printed circuit boards. Then fit the rod into the switch and select 250
V / M Ω .
• Supply 10.5 Volts to the instrument. Place the voltmeter between point T and point D, and
perform the calibration procedure contained in Section d on page 11.
• If the voltage at point T exceeds 0 ± 200 µV when the selector is in the 1000 M Ω position, it
will be necessary to clean all of the printed circuit boards.
• Disconnect the instrument and remove the small white push button for the high voltage
switch, the push button cap, and the respective ball bearing and spring. These components
should not be placed in the cleaning solution while the circuits are soaking. After drying,
reinstall these items within the panel and perform all of the indicated calibration
procedures. (Consult Section b on page 10)
3) The battery light is lit and the beeper operates properly but measurement is
not possible:
Select the 250 V / M Ω range and connect a voltmeter set to the 1000 Volt range to the
measuring terminals.
(a) No voltmeter movement (control component not functioning).
• The circuit boards will have to be removed.
• Place the circuit boards upon the respective supporting layer (transformer facing up) and fit
the rod into the switch. Then select the 250 V / M Ω range.
• Supply 12 Volts to the circuit and verify the supply and reference voltage levels.
It is possible to check the open loop control sequence by adopting the following precautions.
• Open the loop at the point identified as (h) on the high voltage board. Position the high
voltage board switch between the 50 V and 100 V plugs. A finite gain should be established
for the control loop by placing a resistor which can provide a sufficient number of K Ω
between the lugs identified as (2) and (3) within (Z1).
• The control loop should be placed in operation by supplying a voltage level of + 5 V (to
start from zero) to approximately + 2.5 V at point (h). This voltage level corresponds to the
theoretical control point.
4/21/2005
REPAIR AND CALIBRATION MANUAL
18
REV. 7: March 13, 2004
FILE LOCATION: Manuals - Cal. Man - 1000MAN.DOC
CAT. #185.100