Philco 77 User manual

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Radio Service Bulletin-No. 13
Models 77 and 77 A Receivers
Model 77 Receivers are for operation on 110-120volt, 50-60 cycle AC lines
Model 77A Receivers are for operation on 110-120volt, 25-60 cycle AC lines
Table 1-Tube Socket Readings Taken with AC Set Tester AC Line-115 volts
TUBE FILAMENT PLATE SCREEN CONTROL CATHODE PLATE
VOLTS VOLTS GRID GRID VOLTS MILLI-
TYPE CIRCUIT VOLTS VOLTS AMPERES
24 1st R. F. 2.3 145 90 3 13 3.5
24 2d R. F. 2.3 145 90 3 13 3.5
24 Detector 2.3 36* 30t 1.4 12 0
27 1st A. F. 2.3 140 1 10 3
45 2d A. F. 2.2 . 230 46 30
45 2dA. F. 2.2 230 i 46 30
80 Rectifier 4.5 I 50/Plate
All readings taken with antenna disconnected and ground on. Volume control on full.
*Read with a 250,000-ohm voltmeter. tRead with a 100,000-ohm voltmeter.
Table 2-Power Transformer Voltages
TERMINALS
1-2
3
4
5-6
7-8
10-11
A.C. VOLTS
2.67
2.68
5.00
9-12
Rubber Covered Lead 750
No. on Table 3-RESISTOR DATA
Figs. 3 and 4 Terminal Resistance Color
ll-2
2-3
3--4
1-2
3--4
1,400 l
1,500 Long Tubular
2,000
250
800 Short Tubular
100,000 Silver Gray
250,000 White
500,000 Battleship Gray
85 Flatwire wound
Model 77 Condenser Block Part No. 3870
No.on
Figs. 3
and4
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Primary
Center Tap for 80 Plate
Center Tap for 45 Tubes
Heaters of 24 and 27 Tubes
Filaments of 45 Tubes
Filament of 80 Tube
Plate of 80 Tube
Center Tap for 24 and 27 Tubes
Table4-CONDENSER DATA
(Other Than Filter Block)
Volts D.C. With Receiver
Capacity MFD Turned On
.25 {95 on Screen Grid Cond.
15 on Cathode Cond.
.05 150
.5 12
.25 {95 Plate Resistor Cond.
40 Screen Grid Cond.
.00025 40
.01 25
Model 77A Condenser Block Part No. 3871
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Page4 Radio Service Bulletin No.13
COMPENSATING
Always use an oscillator signal when adjusting compensating condensers. With the Receiver set up
for operation, adjust the oscillator and Receiver so the signal is turned in between 120 and 140 on the
tuning scale. Have the Receiver volume control turned on full. Adjust the oscillator so that the received
signal is very weak. Using a fibre wrench turn down on the adjusting nut of the first compensating con-
denser until it is quite tight. This purposely throws the first stage out of balance while adjusting the
second stage.
After tightening this first adjusting nut compensate the second condenser in the usual manner, that
is, tune the Receiver very carefully to the oscillator signal and adjust the compensating condenser for
the maximum signal. After this adjustment has been made, adjust the first compensating condenser in
the same manner.
NEW TUNING SCALE ILLUMINATION
The tuning scale used in the Models 77 and 7_7-Ais translucent and is illuminated by means of.a
pilot lamp placed inside the drum of the tuning condenser. In case it is necessary to replace the pilot
lamp, remove the screw fastening the lamp bracket to the condenser housing and bring the bracket out
over the top of the condenser. Replace the lamp and fasten the bracket in place again. This can be do~e
without removing the chassis from the cabinet.
REPLACEMENT PARTS
No.on No.on
Fi~. 3and 4 Description Part No. Fi~s. 3and 4 Description
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Volume Control . 4094 @ Input Transformer
First RF Transformer 3884-A @ On-Off Switch
Tuning Condenser 4000-B @ Power Transformer (60 Cycles)
First Compensating Condenser. 3968-A Power Transformer (25 Cycles)
Second RF Transformer. 3884-B @ Pilot Lamp
Second Compensating Condenser 3772-A ® BC Resistor
By-Pass Condenser 3557 ® Choke.
Coupling Condenser . 3892-A @ Filter Condenser (60 Cycles)
Third RF Transformer 3884-C Filter Condenser (25 Cycles)
Fourth RF Transformer. 3884-C @ C Resistor.
By-Pass Condenser 3615-D @) BC Resistor
Resistor 3767 @ Output Transformer
By-Pass Condenser 3583 @) Voice Coil and Cone
By-Pass Condenser 3557 @ Field Coil .
Resistor 3768 Knob (Volume Control)
By-Pass Condenser 3082 Knob (Tuning Condenser)
Resistor 3769 Knob (On-Off Switch)
Resistor 3767 Dial Indicator
Condenser 3903-F Scale
Resistor 3769 Speaker Plug and Cable (Short)
Tone Control 4037-A Speaker Plug and Cable (Long)
PHILADELPHIA STORAGE BATTERY COMPANY
Ontario and C Streets, Philadelphia, Pa.
Part No.
3872
4095
3868
3869
3463
3864
3422
3870
3871
4121
3865
2848
2794-B
2850
3579-A
3580-A
3676-A
4006
4118
L-1101-A
L-1102-A
May, 1930 Form No. ;?320 Printed in U.S. A.
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