Input To Demodulator - HP 3400A Operating And Service Manual

Model 3400A
Section
V
Table 5-6.
Troubleshooting Procedure
i
CHECK
PROCEDURE ACTION
®
©
Apply a
1 volt
400
Hz
signal
and
set the
3400A
to
the
1
volt range.
Measure
ac signal
at
junction
of
C413 and C415.
The reading should be between
240
mV
and 280
mV
RMS.
PASSES: Proceed
to
©
FAILS:
Proceed
to
(l9)
(Trouble proceeding
the
Chopper
Amplifier)
PASSES: Proceed
to
®
FAILS: Proceed
to
©
(Trouble in the
Chopper
Amplifier).
Do
not
use an extender board
for
measurements on Chopper
Amplifier
board
A6.
Measure
ac
signal at
junction
of
C605 and
Demodulator V503 and
V504.
Refer
to
Figure
5-6
for
waveform.
Figure
5-6.
Input to
Demodulator
Table 5-6.
Troubleshooting Procedure
(Cont'd)
CHECK
PROCEDURE
ACTION
®
©
Investigate
meter
(Ml), R5,
and R6
for opens.
Remove
the
input to
3400A. Unsolder red lead
from
pin 13 (A6)
and insert
a +10
mV
dc signal
from
738BR through a 499
kfi
resistor (-hp-
Part
No. 0757-0327)
to pin 13.
Measure
ac signal
at
positive side of
C605.
Refer
to
Figure
5-7
for
waveform.
PASSES: Proceed
to
©
FAILS: Proceed
to
@
01768-4
5-9