HP 428B, Operating And Service Manual, Page: 51 / 52

Model 428B
44
5-58.1. OUTPUT ADJUSTMENT.
5-58.2. A meter calibrator and a one kilohm resistor
are required for his test.
a. Place RANGE switch in 10 amp position
and adjust R46 for zero volts DC ± 0.2 mV at
the· Output Level jack.
b. Switch the 428B and the meter calibrator to
the 100 mA range. Connect a test lead
between the meter calibrator output leads and
clip the 428B probe to the lead.
c. Set the meter calibrator to 100 mA output
and read full-scale on the 428B. Adjust R69 if
necessary.
d. Connect a voltmeter to the output jack of the
428B in parallel with the 1000 ohm resistor.
e. The voltmeter should read 0.73 V ± 10m V.
Adjust R63 if necessary.
Page 5-8, Paragraph 5-69. Replace V11 by Zener
diodes CR10, CR17.
Page 6-2. Change CR13 through CR16 to 1906-0034,
Duo-Quad, -hp-, for all replacements.
Change C63 part no. to 0160-2025.
Pages 6-2/6-3. Change C24, C52, C55, C70, and R60
to "starred" (selected) components.
Nominal values are as follows:
C24, 0160-0138, .39 µF, 200 Vdcw.
C52, 0140-D178, 560 pF, 300 Vdcw.
C55, 0140-0197, 180 pF, 300 Vdcw.
Page 6-3. M1 is a 0 - 5 mA meter.
Pages 6-3 and 7-5. Change R 15 to 216
Ω
.
Page 6-4. R82 is 2 K/200 ohms.
Page 6-5. Part Numbers in the Operating and Service
Manual are for blue instruments; part numbers for
brown instruments are listed below.
00428-00204 Dust Cover (rack only)
00428-62101 Probe Assembly
00428-00201 Panel (cabinet only)
00428-00203 Panel (rack only)
00428-64401 Assembly: cabinet
5020-6849 Bezel
►
Page 6-6,Fig. 6-1. Change Part No. of Coil Spring by
probe nose section to 1460-0600 and change PIN of
Cable Clamp by connector plug to 00428-41201.
Page 7-1. Note that resistors are in ohms and
capacitors are in pF unless otherwise marked, and that
selected ("starred") components marked wit an
asterisk may not even be present.
Page 7-3, figure 7-5. TP5 is connected to pin 1 of V9.
Reverse F1 and F2.
Page 7-3, Figure 7-2; Page 7-5, Figure 7-7. Change
CR13 (near TP2) to CR11.
Interchange: R26/R30; R27/R29 and C14/C18.
Page 7-5, Figure 7-10. R8 is 40 ohms. R68 is 50
ohms.
R61 is 45 ohms.
R62 is 90 ohms.
R 12 through R20 may be any mixture of the values
shown on Pages 7-5 or A-D.
Nominal value of C52* is 560 pF.
Nominal value of C55 * is 180 pF.
C2 is 16 - 150 pF.
R91 is not a "starred" component; it is no longer a
selected value.
Page 7-5/A-0. Add another contact to S1A as shown:
Page A-0. R41 is 28.4 K. Change R78 (near CR11) to
R71. Add R65 between the junction of R61, R62 and
54 (as in Figure 7-10). Change R60 to R60*. Change
the LINE switch (230 V-115 V) from S3 to S5. Change
the power transformer from +7v to T7. R33 is 12.3 K.
Page A-2. Add CR11, CR12 as on page 6-2.
Pages A-2, A-3. R 12 through R20 may be individually
replaced by the parts shown on Page 6-3.
Page A-4. Add R111, R112 as on page 6-4.
CHANGE NO. 1: For Serial 0995A06603 and Greater.
Page 6-2. Add C33*, 0140-0149 C: fxd 470 pF 300 V.
Add C72* 0160-0174 C: fxd .47 µF 25 V.
Page 7-5. Add C33*, 470 pF, between base and
collector of Q3. Add C72* .47 µF between emitter and
collector of Q3
.
10 April 1974