Test Equipment; Power Supply Checks; Low Frequency Calibration - HP 3400A Operating And Service Manual

Model 3400A
c. When the pointer is exactly at zero, rotate
the adjusting screw slightly counterclockwise
to remove tension on pointer suspension.
the meter }X)inter moves to the left during
this adjustment. repeat steps b and c.
5-19.

POWER SUPPLY CHECKS.

5-20. Power supply voltage and ac ripple tolerances
are listed in Table 5-4.
cated in this table . When making ripple voltage
measurements. it may b e desirable to use a bat ­
tery powered A. C. Voltmeter (H-P 403B) to avoid
any undesirable ground loop currents.
5-21.

LOW FREQUENCY CALIBRATION.

5-22. AMPLIFIER GAIN ADJUSTMENT.
Connect test setup illustrated in Figure 5 - 1 .
a.
b. Set Model 3400A RANGE switch to 0 . 0 1 volt
position.
c. Adjust Voltmeter Calibrator for 0 . 0 1 volt
O.
rms. 400 Hz output; set DC Voltmeter to
read 1.
d. Remove Model 3400A top cover; adjust R4
(CAL) for 1. 0 volt as indicated on DC Volt-
If
meter.
R4 (CAL) does not have enough
range to calibrate the dc output. the value of
R3 should be changed.
from 820 ohms to 2 . 16 k ohms.
e. Adjust R6 (FULL-SCALE ADJUST) for Model
3400A full-scale meter indication.

TEST EQUIPMENT

POWER
AND
SUPPLY
CHECK POINT
-17. 5 Vdc COlU1ect DC Voltmeter,
AC Voltmeter, or Os-
cilloscope between
violet lead on video
amplifier (A4) board
and chassis ground.
+75 Vdc Connect DC Voltmeter.
AC Voltmeter. or 05cil-
loscope between red/wht/
blue on video amplifier
A4 and chassis ground.
Connect DC Voltmeter,
-6. 3 Vdc
AC Voltmeter, or Oscil-
loscope between Q3
.emitter (grey lead) and
chassis ground.
Test points are also indi­
The range of R3 is
Table 5-4.
DC VOLTAGE
SPECIFICATIONS
-16.8 to 18. 2 Vdc
70 . 0 to 78. 0 Vdc
-5. 9 to -6. 5 Vdc
5-23. 1/10 SCALE ADJUSTMENT.
If
Connect test setup illustrated in Figure 5-1;
a.
omit the DC Voltmeter.
b. Set Model 3400A RANGE switch to
JX)sition and adjust Voltmeter Calibrator for
0. 0 1 volt rms, 400 Hz output.
The 1/10 SCALE ADJUST should
be set slightly low (needle's width)
to reduce meter (needle) offset
with shorted input.
c .
Adjust R7 (1/10 SCALE ADJUST) for Model
3400A 1/10 scale meter indication.
value of RB
adjustment range of R7. The range of RB is
from approximately 270 ohms to 430 ohms.
See Table 5-7.
5-24. I VOLT ADJUSTMENT.
a. Connect test setup illustrated in Figure 5 - 1 ;
omit the DC Voltmeter.
b. Set Model 3400A RANGE switch to
position.
Adjust voltmeter calibrator for 1. 0 volt rms.
400 Hz output.
d. Remove right side cover (INPUT side) and
adjust R104
full-scale meter indication.
Power Supply Checks
REGULATION
(Vary Line Voltage Between
103. 5 and 126. 5 vac)
± 0 . 5 volt from nominal
reading at 115 Vac line.
± 1 volt from nominal
reading at 1 1 5 Vac line.
± 0 . 1 volt from nominal
reading at 115 Vac line.
Section V
O.
if it
is necessary to increase the
(I
V ADJUST) for Model 3400A
RIPPLE
SPECIFICATIONS
400 MV rms or
1. I mV p-p
J1
400 V rms or
I . l mV p-p
750 /.LV rms or
2 . 0 mV p-p
I volt
Change
I
volt
5 - 5