B&K Precision 1762 - Manual - Manual (Page 42)

42
MAINTENANCE
ADJUSTMENTS
This unit was accurately adjusted at the factory before
shipment. Readjustment is recommended only if repairs have
been made in a circuit affecting adjustment accuracy, or if you
have a reason to believe the unit is out of adjustment. However,
adjustments should be attempted only if a 4-1/2 digit
multimeter with an accuracy of ±0.1% dcv or better is available
(B+K Precision Model 391A or equivalent).
If readjustment is required, use the following procedure. All
references to left and right are correct when facing the front of
the supply. The functions of the adjustments are shown in Table
2 and their locations are shown in Fig. 18.
I. “A” SUPPLY AND “A” METERING ADJUSTMENTS
1. Connect an accurate (±0.1%) external 4-l/2 digit
multimeter to measure the DC voltage at the output
terminals of the “A” SUPPLY.
2. Disengage the INDEP/TRACK mode switch (out) so that
the power supply is in the INDEPendent operating mode.
3. Set the “A” VOLTAGE controls (both Coarse and Fine)
to maximum (fully clockwise).
4. Adjust R6 (“A” SUPPLY +5V REF) on the main circuit
board (located on the right rear side of the supply) for a
reading as close to 30.40 volts (on the multimeter) as
possible.
5. Set the 0-30 V/4-6.5V switch to the 0-30V position and the
Right V/A switch to the V position.
Table 2. Functions of Calibration Adjustments
ADJ FUNCTION OF ADJ LOCATION OF ADJ
R6 “A” SUPPLY +5 V REF. MAIN BOARD
R10 “B” SUPPLY +5 V REF. MAIN BOARD
R119 “B” SUPPLY SERIES
TRACKING MAIN BOARD
R122 4-6.5V A METER & A
LIMIT MAIN BOARD
R133 4-6.5V V METER MAIN BOARD
R134 4-6.5V 3.9V REF. MAIN BOARD
R159 4-6.5V 6.8V REF. MAIN BOARD
R163 “A” SUPPLY A METER MAIN BOARD
R164 “B” SUPPLY A METER MAIN BOARD
R304L “B” SUPPLY V METER “B” PANEL METER
R304R “A” SUPPLY V METER “A” PANEL METER
1. Adjust R304 (“A” SUPPLY V METER ADJ) on
the “A” panel meter board (located on the right side
of the supply behind the “A”/4-6.5V LED Display)
for a reading of 30.4 volts on the “A”/4-6.5V LED
Display.
2. Set the “A” Coarse VOLTAGE control for a
reading of approximately 05.0 volts on the “A”/4-
6.5V LED Display.