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NOTE
The internal temperature rise of the power
supply has an effect on the accuracy of the
programming coefficient. For example, an
interna/ temperature rise of 15°C (typical of
the temperature difference between no-load
and full-load operation) causes the supply
output to change by 0.15%. Since the
factory calibration procedure for instruments
equipped with Option 020 or 040 sets the
voltage programming coefficient to within
0.1%, the resulting accuracy specification
including the effect of the 15°C temperature
rise would be 0.25%.
5-86
Constant-Voltage Programming Accuracy,
Standard Instrument. To calibrate the constant-voltage
programming current of a standard instrument, proceed
as follows:
a. Connect 0.1 %, 1 /8 watt resistor of value shown
below between terminals -S and A2 on rear barrier strip.
Model
Value
6259B
2000ft
6260B
2000ft
6261 B
4000ft
6268B
8000ft
6269B
8000 ft
b. Disconnect strap between terminals A1 and A2 on
rear barrier strip.
c. Connect digital voltmeter between +OUT and -OUT
bus bars.
d. Connect decade resistance box in place of R3
(mounted on standoffs on main circuit board; see Figure
7-7).
e. Rotate CURRENT controls fully clockwise and
turn on supply.
f. Adjust decade resistance box until digital voltmeter
indicates exactly maximum rated output voltage.
g. Replace decade resistance box with fixed, composi¬
tion, 5%, 1/2 watt resistor of same value.
5-87
Constant-Voltage Programming Accuracy, Option
020 Instrument. To calibrate the constant-voltage pro¬
gramming current of an Option 020 instrument, proceed
as follows:
a. Perform steps (a) through (c) of paragraph 5-86.
b. Rotate CURRENT controls fully clockwise and
turn on supply.
c. Adjust potentiometer R112 (labeled "VOLTAGE
PROG" and accessible through hole in rear panel) until
digital voltmeter indicates exactly maximum rated output
voltage.
5-88
Constant-Voltage Programming Accuracy, Option
040 Instrument. To calibrate the constant-voltage pro¬
gramming current of an Option 040 instrument, proceed
as follows:
a. Connect 0.1%, 1/8 watt resistor of value shown
below between terminals -S and A2 on rear barrier strip.
Model
Value
6259B
2010ft
6260B
2010ft
6261B
4010ft
6268B
8010ft
6269B
8010ft
b. Disconnect strap between terminals A1 and A2 on
rear barrier strip.
c. Connect digital voltmeter between +OUT and -OUT
bus bars.
d. Rotate CURRENT controls fully clockwise and
turn on supply.
e. Adjust potentiometer R112 (labeled "VOLTAGE
PROG" and accessible through hole in rear panel) until
digital voltmeter indicates full rated output voltage ±0.1%.
5-89
Constant-Current Programming
Calibration
5-90
To calibrate the zero current programming
accuracy, proceed as directed in paragraph 5-91,5-92,
5-93, 5-94, or 5-95 whichever applies to your particular
instrument. To calibrate the constant current program¬
ming accuracy, proceed as directed in paragraph 5-96 or
5-97.
5-91
Zero Output Current, Standard Instrument With
Resistance or Fixed Gain Voltage Programming. For
instruments using either local programming or the remote
programming setup shown in Figure 3-7 or 3-8, zero the
output current as follows:
a. Connect test setup shown in Figure 5-7.
b. If unit is to be used in local programming mode,
turn CURRENT controls fully counterclockwise. If unit
is to be used in remote programming mode, connect remote
programming setup and adjust remote resistance or voltage
to zero.
c. Connect decade resistance box between pads in zero
adjust section of A1 main circuit board that are marked
"G" and "H" in Figure 5-9. (These pads are for R117.)
d. Rotate VOLTAGE controls fully clockwise and
turn on supply.
e. Adjust decade resistance box until digital voltmeter
reads exactly zero volts.
f.
Replace decade resistance box with fixed, metal
film, 1%, 1/4 or 1/8 watt resistor of same value.
5-18
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