HP 206A - Page 27

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TROUBLE SHOOTING CHART
assistance in trouble shooting a defective instrument.
TEST PROCEDURE AND REMEDIES
Replace fuse, if this fuse blows remove
V10, and again
replace the fuse:
If this fuse blows it is an indication of;
1. Short circuit in wiring associated with power trans-
former,
T1.
2. Short circuit in filament wiring.
3. Defective power transformer.
If the fuse does not blow when V10 is removed, it in-
dicates:
1. Defective rectifier
V10.
2. Short in direct current wiring.
3. Defective filter capacitor.
Measure oscillator voltage between center tap of R18
and ground; it should be 27-29 volts at
1000 %.
If the
oscillator voltage is present but of incorrect value
refer to Replacement of Lamp R13 (par. 4-3); if oscil-
lator voltage not present check:
1. Oscillator tubes V1 and V2, and Lamp R13.
2. The DC voltages in the oscillator section should
agree with those indicated on the schematic diagram
within
f 10qo.
3. A short circuit in tuning capacitor or associated
trimmers.
If foreign material is causing short remove
carefully; if plates have been damaged and
are touching, carefully straighten.
4. RANGE switch
(Sl) contacts may be dirty and not
making good contact, or if trouble is on one band
only it may be due to an open resistor.
Clean RANGE switch
(Sl) contacts or replace
RANGE switch assembly if any resistor is
defective. Recommended that instrument
be
returned to factory for such replacement;
a reasonable charge will be made for this
service.
Check DC voltages in amplifier sections (V3 through
V9); they should agree with voltages indicated on
schematic diagram within
+lo%.
Measure power supply voltages and regulator output
voltage. See paragraph 4-6.
1. Check oscillator output voltage: between center tap
of R18 and ground should measure 27-29 volts.
Reset oscillator output voltage (par. 4-7).
2. Check distortion at oscillator output: should be
-50 db or better.
Replace
V1, V2.or lamp R13.
1. Remove V6. At 1 kc there should be 28-30 db gain
from grid of V3 to cathode of V5.
Replace V3, V4, and/or V5.
The following information
SYMPTOMS
Instrument NOT
operating, pilot light
NOT on.
lnstrument NOT
operating, pilot
light ON.
Instrument operating,
high amount of
distor-
tion present in out-
put.
is designed to be of
POSSIBLE CAUSE
Line fuse blown due
to defective fuse,
power
line surge,0r
overload in power
supply section of the
instrument.
Oscillator section
not operating.
Oscillator voltage
correct, amplifier
sections NOT oper-
ating properly.
Incorrect DC voltages.
Distortion in oscil-
lator section.
Incorrect gain through
selective amplifier
section.