Farnell TOPS 3D - Page 15

7. Turn P6 anticlockwise until 'overload' led in + ve output
switch just illuminates. Back of P6 slightly so that led is
extinguished. Remove load and ammeter.
8. Turn +6V output 'volts adjust' control fully anticlockwise and
connect voltmeter across +6V terminals.
9. Adjust P8 (set min V) to give an output of 3.90 volts.
10. Turn 'volts adjust' fully clockwise and adjust P9 (set max V)
to give an output of 6.10 volts.
11. Turn P7 fully clockwise, connect load in series with reference
ammeter and adjust ioad to give current of 4 amps.
12. Turn P7 anticlockwise until 'overload' led in +6V output
switch just illuminates. Back off P7 slightly until led exX
tinguished.
13. Remove load and ammeter.
Display section
1. Ensure all push buttons are out (i.e. set for measuring ex
ternal voltages). Switch TOPS 3D on and connect together
the + and - pins of SK3.
2. Adjust 'Set zero' pot (P2) until voltmeter reads 00.01, then
back off P2 slightly until reading just changes from .01 to
00. Remove shorting connection between + and - pins.
3. Feed 395.0mV into SK3 observing polarity marked on the
pins. Adjust P1 (set full scale) until voltmeter reads 39.50.
4. Remove connections from SK3 and feed 39.50 volts into ex
ternal voltmeter socket (observe polarity). Adjust P3 (cal V)
until the voltmeter reads 39.50 volts. The voltmeter is now
calibrated and can be checked for linearity if required.
5. Connect together + and - pins on SK4 and adjust P8 (set
zero) for current meter to read 0.001, back off P8 slightly
so that reading just changes from 0.001 to 0.000.
6. Feed 395.0m V into SK4 observing polarity and adjust P7
(set full scale) such that meter reads 3.950 amps.
The meter is now calibrated in voltage only and may be
checked for linearity.
7. Connect load in series with reference ammeter to -17V term
inals and adjust for 1 amp load current on reference ammeter.
8. Depress -17V push button and adjust P5 (cal |-17V) such that
TOPS 3 current meter reads the same as reference meter
to within 1 digit.
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