Guildline 6675A - Page 149

Section 7
7-19
5. a) Link Rs C
1
to Rs P
1
. Link Rs P
2
to Rs C
2
.
b) Connect a 10 , 0.01% GR resistor across Rs P
1
and Rs P
2
.
c) Link Rx C
1
to Rx P
1
. Link Rx P
2
to Rx C
2
.
d) Connect a 10 , 0.01% resistor across Rx P
1
and Rx P
2
.
e) Re-enter Sofcal Diagnostic mode, set the number of turns to
0. While observing the waveform on the Scopemeter, set the
number of turns to 8747.
f) Check that rail-to-rail ringing dampens quickly when the
turn switching is done.
g) Set the turns to 648 and 6480.
h) Check that waveform at TP200 is less than 2.5 Vp-p
(including 50/60 Hz envelope).
i) Exit Sofcal Diagnostic mode.
6. If the DC level is out of tolerance or the rail to rail ringing does not
dampen quickly or the TP200 waveform amplitude is greater than
2.5 V p-p, the Servo-loop circuits may require adjustment. Due to
the complexity of the adjustments, it is recommended that these
adjustments be done at the factory. Contact Guildline Instruments
for further information.
7.2.4.3.5.Servo-loop Adjustments (Board 19107)
a) A/D Converter Calibration
1. Leave the 10 , 0.01% GR resistors and the links connected to the
Rs and Rx test set front panel terminals.
2. Connect a precision voltage standard (set on its 20 V range) to
TP305 and TP302 on the Servo-loop PCB (connect the positive
terminal of the standard to TP305). Leave the standard's output
disabled.
3. Turn the 6675A Power ON and enter the Sofcal Diagnostic menu.
4. Select the "Monitor" function by pressing the corresponding menu
key.
5. Set the voltage standard for +9.9927 V and enable the standard's
output.