Factory Selected Components - HP 333A Operating And Service Manual

Section V
Model 333A/334
lem. Theseoperations should
be
undertakenonly after
it has been established that the difficulty cannot be
eliminated by the Adjustment and Calibration Proced-
ures.
An
investigation should also be made
to
insure
that the trouble
is
not a result of conditions external
to the 333A/334A.
5-35. Conduct
a
visual check of the 333A/334Afor
possible burned or
loose
components, loose connec-
tions, or any other obvious condition which might
suggest
a
source of trouble.
THE 333A/334A CONTAINS
VERY
HIGH
IMPED-
ANCE. HIGH FREQUENCY CIRCUITS. CON-
TAMINATIONOFTHE SWITCHES, CIRCUIT
BOARDSOR TUNXNGCAPACXTORWILL CAUSE
HIGH IMPEDANCE LEAKAGE PATHS AND
SUBSEQUENT DETERIORATION OF THE
PERFORMANCE OFTHE INSTRUMENT.
AVOIDTOUCHINGANYOFTHESE CIRCUITS
WITH THE
BARE
FINGERS, AS SKIN OILS
ARE
EXTREMELY CONTAMINATING.
5-36. Table 5-8 contains
a
list of typical front panel and
internal trouble symptoms, as well as the probable cause
oftrouble. If the instrument malfunction cannot be loca-
tedthrough use of the table, refer to Paragraphs 5-38
through 5-44.
I
COMPONENT
A2C22*
A2C23*
A2C30*
A2C29*
A2R30*
A3Cll*
A3R17*
c 9
*
Ft3*
S3R14*
S4R6* through
S4Ft26*.
5- 37. Trouble in the Model 333A/334A can g e n e r w
be isolated to circuits of one of the two principu
instrument functions-voltmeter or distortion.
order for the distortion function to Operate properly,
the voltmeter function must operate properly. There-
fore, troubleshoot the voltmeter function
first to
assure that
it
works normally before attempting
ta
locate a
trouble in
the distortion function.
558. TROUBLESHOOTING VOLTMETER
FUNCTION.
5-39. Follow the steps below
to
troubleshoot the volt.
meter function:
a.
b.
C.
Set 333A/334A controls as follows:
FUNCTION
.
.
. .
. .
.
.
.
.VOLTMETER
Connect a 1 V rms, 1 lrHz
signal
to 333A/
334A INPUT TERMINALS.
METER RANGE.
. .
.
.
1 VOLT
Measure ac output of impedance converter
at A2-pin 4 for approximately 1 mV rms
(Use 10 M51/10 pF impedance probe), If
proper signal i s present, proceed to step c;
if
not proceed
to
step d .
Measure
ac
input to meter amplifier at A2-
pin 6for approximately 1 mVrms.
If
proper
signal is present, check meter amplifier
circuit. (See schematic diagram of Fig-
Table 5-7. Factory Selected Components
FUNCTION
Sets range of A2C21
Adjusts meter frequency response
in 2 MHz region
Adjusts meter frequency response
in 20 Ha region
Adjusts meter flatness on 0.0003 V
range at 300 lcHz
Adjusts meter amplifier gain on
0.0003 V range a t 400 Hz.
Adjugts bridge amplifier frequency
response in 1 MHz to 3 MHe region
Adjusts gain of rejection amplifier
Adjusts tracking of frequency
dial
Adjusts range of S2R8
Adjusts flatness of 1OOO:l
atten-
uator in 2 MHz to 3
M?iz
region
Must be individually matched
to be
f
1/48
Low
0 PF
100 pF
10 p F
0 PF
15051
56 pF
1 k51
0 PF
051
7.551
--
VALUE
Normal
47 pF
240 pF
22 p F
390 pF
30051
127 pF
2 k52
2.2 pF
39052
100
--
High
47 pF
320 pF
50 p F
680 pF
300
SZ
127 pF
3 k51
6.8 pF
39051
1051
5-12