HP 206A - Trouble Shooting Chart

SYMPTOMS
Instrumentoperating,
high amount of distor-
tion present in out-
put. (Cont'd.
)
Instrument operating
high distortion and/
or high output voltage
on one range only.
Noise and instability
of output waveform.
Calibration off on
all ranges.
Voltage at OUTPUT
terminals below
rated level.
Waveform at OUT-
PUT terminals
shows clipping.
-
TROUBLE
POSSIBLE CAUSE
Incorrect gainthrough
selective amplifier
section. (Cont'd. )
Distortion in inter-
mediate or output
amplifiers.
Defective resistor in
selective amplifier
tuned bridge.
AMPLITUDE control
(R57) dirty or worn.
C10, C11, or C26
leaky.
Short or dust in
tuning
capacitor C3.
Tuning capacitor
C1
damaged or slipping.
Oscillator output
voltage low.
Selective amplifier
gain too low.
Selective amplifier
gain too high.
SHOOTJNG CHART (CONT'D. )
TEST PROCEDURE AND REMEDIES
2. With
V6 in circuit,
at
1 kc gain from grid of V3 to
cathode of
V5 should drop to approximately 24 db
(see Adjustment of Selective Amplifier Gain
par. 4-8).
a. Replace
V6 and/or V7.
b. Blow dust out of tuning capacitor C3.
3. Check DC voltages in selective amplifier section.
Replace defective part and reset gain
(par. 4-8).
Replace each tube (V3 to V9) individually and recheck
distortion.
For range in trouble, measure resistors in amplifier
section of RANGE switch, and R39 or R93.
Replace defective resistor. (Ordinarily
re-
placement of a Wilkor with a Wilkor of the
same marked value will be satisfactory.
If
not, replace RANGE switch assembly. See
CAUTION preceding par. 4-12.
Check resistance between center tap of R57 and ground
for smooth variation with rotation of AMPLITUDE con-
trol. (Disconnect instrument from power line when
making resistance measurements.
)
Replace R57.
Test by substituting capacitor of same value known
to
be good.
Check visually.
Remove short, and/or blow dust out of tuning
capacitor C3.
Check visually.
1. Re set position of tuner, and tighten Allen
setscrews on tuner drive.
2. Replace tuning capacitor C 1. (See CAUTION
preceding par. 4-12.
)
Measure voltage from center tap of R18 to ground;
should be 27-29 volts (see par. 4-7).
1. Check
V1 and V2.
2. Adjust R18.
3. Check lamp
R13. See par. 4-3.
See Adjustment of Selective Amplifier Gain.
Par. 4-8.
Adjust R96.
See Adjustment of Selective Amplifier Gain, par. 4-8.
Adjust R96.