HP 333A Technical Manual Download Page 35

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Model 333A/334A

NOTE

Selector positions for the
selector will be referred

SENSITIVITY

to as follows:

MIN = Position 1, next step = Position

2, etc. , to MAX = Position 6.

Set Distortion Analyzer controls as follows:

FUNCTION Selector . . . . . . . SET LEVEL
SENSITIVITY Selector . . . . . .Position 5
SENSITIVITY VERNIER Control . . . . . MAX

METER RANGE Selector . . . . 0.01 VOLTS

Set Frequency Response Test Set controls (-hp-

Model 739AR)as follows:

RANGE SELECTOR . . . . . . . . EXTERNAL
OUTPUT ATTENUATOR . . . . . . . . 0.03

d. Set Oscillator (-hp- Model 200SR) frequency to

400 cps. Adjust AMPLITUDE control for an indica-
tion on Distortion Analyzer meter of 0. 9 on the 1. 0)
scale.

e. Adjust Frequency Response Test Set METER

SET for SET LEVEL indication.

f. Change Oscillator frequency to 100 Kc. Read-

just Oscillator AMPLITUDE control for SET LEVEL
indication on Frequency Response Test Set meter.

g. Adjust S2C 5 for a meter indication of O. 9 on the

1.0 scale.

h. Repeat steps d through f, calibrating sensitivity

at the settings indicated in Table 5-7.

NOTE

When switching the SENSITIVITY selector,
be careful not to move SENSITIVITY VERN-

IER control from MAX position.

Table 5-7. Sensitivity Switch Calibration

SENSITIVITY

Test Set

Adjust

Switch ATTENUATOR for 0

9 I

Position 5 0.03 S2C 5

Position 4 0.1 S2C 4

Position 3 0.3 S2C 3

Position 2 1.0 S2C2

Position 1 3.0 S2C 1

5-33. TROUBLESHOOTING PROCEDURES.

5-34. This section contains procedures designed to as-
sist in the isolation of malfunctions. These procedures

are based on a systematic analysis of the instrument
circuits in an effort to localize the problem. These
operations should be undertaken only after it has been
established that the difficulty can not be eliminated by
the Adjustment and Calibration Procedures. An in-
vestigation should also be made to insure that the
trouble is not a result of conditions external to the
333A/334A.

THE 333A/334A CONTAINS VERY HIGH
IMPEDANCE, HIGH FREQUENCY CIR-
CUITS. CONTAMINATION OF THE

SWITCHES, CIRCUIT BOARDS OR TUN-
ING CAPACITORS WILL CAUSE HIGH

TM 11-6625-1576-15

Section V

Paragraphs 5-33 to 5-42 and Table 5-7

IMPEDANCE LEAKAGE PATHS AND SUB-

SEQUENT DETERIORATION OF THE PER-
FORMANCE OF THE INSTRUMENT.

AVOID TOUCHING ANY OF THESE CIR-
CUITS WITH THE BARE FINGER, AS
SKIN OILS ARE EXTREMELY CONTAMI-
NATING. IF HANDLING IS NECESSARY,
WEAR CLEAN COTTON OR RUBBER

GLOVES. DO NOT USE A PENCIL TO
TRACE CIRCUITS IN THE INSTRUMENT.
GRAPHITE PENCIL LEAD IS AN EX-
TREMELY GOOD CONDUCTOR AND MN
ACCIDENTLY INTRODUCED PATH OF
THIS TYPE IS SOMETIMES DIFFICULT
TO LOCATE. TO AVOID SURFACE CON-
TAMINATION OF A PRINTED CIRCUIT
OR SWITCH, CLEAN WITH A WEAK SO-

LUTION OF WARM WATER AND MILD DE-

TERGENT AFTER REPAIR. RINSE THOR-
OUGHLY WITH CLEAN WATER AND
ALLOW IT TO DRY COMPLETELY BE-

FORE OPERATING. DO NOT USE ALCO-
HOL OR ANY OTHER CLEANING SOLU-
TION EXCEPT DETERGENT AND WATER.

DO NOT APPLY ANY COMMERCIAL
MOISTURE SEALING SPRAY TO THE
BOARDS. APPLICATION OF THESE
AGENTS WILL CAUSE LEAKAGE PATHS
AND SUBSEQUENT DETERIORATION TO
THE OPERATION OF THE INSTRUMENT.

5-35. Conduct a visual check of the 333A/334A for

possible burned or loose components, loose connec-
tions,

or any other obvious condition which might

suggest a source of trouble.

5-36. Table 5-8 contains a summary of the front panel
symptoms and internal adjustment symptoms that

might be encountered. It should be used in initial
efforts to select a starting point for troubleshooting

procedures.

5-37. Table 5-9, in conjunction with Figure 5-10, con-

tains procedures which may be used as a guide in

isolating malfunctions. The steps in Table 5-9 de-
scribe the normal conditions which should be encoun-

tered during the checks (circled numbers N ) in

Figure 5-10.

5-38. The checks outlined in Table 5-9 are not designed

to measure all the circuit parameters, rather to local-

ize a malfunction. Therefore, it is quite possible that
additional measurements will be required to complete-
ly isolate a problem.

Circuit parameters may vary

slightly between instruments; therefore, it should not

be necessary to precisely duplicate the values given.

5-39, BOTTOM SHIELD REMOVAL.

5-40. The bottom shield is attached by seven screws.

Access to six is obtained by removing the bottom
cover. Access to the other is obtained by removing
the left (as viewed from the front of instrument) rear
side cover.

5-41. SERVICING ETCHED CIRCUIT BOARDS.

5-42. The Model 333A has six-etched circuit boards

and the Model 334A, seven. Use caution when re-
moving them to avoid damaging mounted components.

5-11