OFFICIAL RADIO SERVICE MANUAL
Supplement No. 5
308-I
lk
PHILCO RADIO & TELEVISION CORP.
PHILCO
Service Bulletin
p -a No. 134
Changes in Models 71
-
22L
-
91
-
23X
-
15
A number of changes, made in the various
new models since the service bulletins were issued, are listed above.
Since these changes represent minor constructional
improvements, it will be unnecessary to alter
any sets in stock
except when difficulty is experienced.
It is suggested that you mark
up your copies of the bulletins so as to agree
with the latest production. The changes noted
can be easily understood if a bulletin is marked in this
manner.
All Philco Radio chasses bear
a rubber stamped number on the back of the chassis.
This is known as a "run
number" and is used to designate minor constructional
changes.
Models 71-22L
Refer to Service Bulletins 128--128-A.
Below run No. 4, unsolder top (ungrounded)
connection of volume control 0 and substitute in the
circuit a
240,000 ohm resistor, part 4410, one end grounded.
Disconnect the condenser g .01 Mfd., part 3903-J, from the
center tap of the volume control and from its
common connection with the control grid of the detector amplifier
tube and the ungrounded end of @ resistor
1,000,000 ohms 4409. This resistor is
no longer used, and can be removed.
Solder one side of the condenser @
to top of volume control and other side of condenser
to ungrounded end
240,000 ohm resistor.
Solder the control grid lead of the detector
amplifier tube to the variable
arm connection
of the volume control tube.
®-A Condenser .25 Mfd. part 04997, change
to .5 Mfd. part 05150.
Resistor 25,000 ohms 4516 used
on both 121 and 221 models.
Dial complete, part 03031, change
to part 04832.
Add tuning condenser drive cord,
part 04834 and spring 6508.
Models 91-121-221 and Model 23X
Refer to Service Bulletins No. 129 and
129-A.
Below run No. 5.91-121-221 and
run No. 4 Model 23X change ® resistor 1,000,000 ohms
to 2,000,000 ohms,
part 5872. Change ® resistor 1,000,000 ohms
to 2,000,000 ohms, part 5872.
Below run No. 4-91-121-221,
run No. 3 Model 23-X, add a 490,000 ohm resistor, part 4517,
across the two
outside terminals of the volume control.
Below run No. 3.91-121-221,
run No. 2 Model 23 X change @ condenser .001 Mfd.
part 6773 to .002 Mfd.,
part 6853.
Change 0 power transformer 6557
to 6804.
All 91.221 and 23 chassis using
power transformer part 6804, use B. C. resistor (4.6\-A
part 6808. Thisne w
B. C. resistor does not use section 1.2 in
series with center tap of high voltage secondary of
power transformer.
When replacing 6557 with 6804
use either 6808 B. C. resistor, or 6807 without connecting
section 1-2.
Change @ B.C. resistor part 6071
to part 6702.
(;) Shadow tuning, part 6477 change
to part 6497.
Add tuning condenser drive cord,
part 04834 and spring 6508.
Model 15
Refer to service Bulletin No. 130.
Below run No. 26 interchange the
two outside wires of the input transformer secondary.
Below run No. 27 change 0, resistor
490,000 ohms to 1,500,000 ohms, part 7009. Change
resistor 1,000,000
ohms to 2,000,000 ohms, part 5872.
Below run No. 25, place
a 490,000 ohm resistor, part 4517, across two outside terminals of
volume control.
Below run No. 22 add .002 Mfd. condenser
part 6853 across the plates of the pentodes.
Add tuning condenser drive cord,
part 04916 and spring 6508.
@ Electrolytic condenser (.6 Mfd.)
part 6707 changed to 4916.
® Electrolytic condenser (.6 Mfd.)
part 6706 changed to 4916.
Model 22L and 23X
Phonograph motor circuit controlled by radio
A.C. switch.
This is done by changing A.C.
power leads to
motor from live side of the radio A.C. switch
to the transformer side. Change switch indicator 4227
to 4277.
In the Philco Parts Catalogue under Power
Transformers change 71.221 part 6454
to 6457. Change 71-A-221
part 6455 to 6458. Change 91.221 part 6557
to 6804. Change 91-A 221 part 6558 to 6805. Under
Input Trans-
formers, add part 3241 for Model 3.
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