GE Superadio (1) Manual

Re-typed in HTML format, remaining as faithful as possible to the original.

GENERAL ELECTRIC
SERVICE INFORMATION
MODEL
7-2880A
FM/AM
PORTABLE RADIO


FILE TAB 7

CAUTION: THIS MANUAL IS DESIGNED FOR USE BY QUALIFIED ELECTRONIC TECHNICIANS ONLY. CONSUMER
USERS ARE URGED TO CONTACT QUALIFIED FACTORY AUTHORIZED SERVICE FACILITIES FOR REPAIRS.

FEATURES
  • Tuned RF on FM and AM improves reception
  • 38" swivel whip FM antenna
  • 7 7/8" ferrite rod AM antenna
  • 4 IF tuned circuits on AM
  • AFC (Automatic Frequency Control) reduces FM drift
  • AFC defeat switch for fine tuning of adjacent stations
  • Precision vernier tuning
  • 6 1/2" high sensitivity speaker
  • 700mW RMS audio output
  • Separate bass and treble controls to personalize sound
  • Loudness control boosts bass at low listening levels
  • 2-Way power with built-in AC cord
  • Automatic switching from AC to batteries


SERVICE SPECIFICATIONS
ELECTRICAL 120
9		 Volts AC, 60 Hz
Volts DC Battery
BATTERIES (6) D Size Batteries
TUNING RANGE AM
FM		 530 kHz - 1610 kHz
88 MHz - 108.3 MHz
IF FREQUENCIES AM
FM		 455 kHz
10.7 MHz
POWER OUTPUT
10% DISTORTION		 700 mW RMS
Minimum
SPEAKER IMPEDANCE 8 Ohm
SENSITIVITY AM Better than 150 uV/M for
20 dB quieting
FM Better than 25 uV (IHFM
Sensitivity
SELECTIVITY AM 65 dB (Minimu) for 2 ACA
Selectivity
FM 50 dB (Minimum) for 2 ACA
Selectivity
MINIMUM VOLUME
HUM		 5 mV or Less
CURRENT DRAIN
IDLE CURRENT		 AM
FM		 20 mA Maximum
26 mA Maximum


ALIGNMENT PROCEDURE

AM ALIGNMENT - FUNCTION SWITCH IN AM POSITION

AM Generator - RF Radiated Signal Modulated 30% at 400 Hz
GENERATOR
FREQUENCY		 RADIO DIAL
SETTING		 INDICATOR ADJUST REMARKS
1. 455 kHz Closed
Output Meter

Across Speaker		 T4, T5, T6, T9 Adjust for maximum. Repeat
until no further improvement
is noted.
2. 1630 kHz Open C1L Adjust for maximum
3. 510 kHz Closed L5 Adjust for maximum. Repeat
steps 2 and 3 until set will tune
to both band end frequencies.
4. 1400 kHz Tune to Signal C1J, C1K Adjust for maximum
5. 580 kHz Tune to Signal T10, L6 Adjust for maximum. Repeat
steps 4 and 5 until no further
improvement is noted.

FM ALIGNMENT - FUNCTION SWITCH IN FM POSITION

High Side of FM Sweep Generator thry a 0.04uF capacitor to TP1, Use only enough Marker Signal for Indication.
GENERATOR
FREQUENCY		 RADIO DIAL
SETTING		 INDICATOR ADJUST REMARKS
1. 10.7 MHz Open Scope at TP2.
Use Pad (See
Figure 1)		 T1, T2, T3 Adjust for maximum gain and
symmetry. Repeat as necessary.
2. 10.7 MHz Open Scope at TP3.
Use Pad (See
Figure 2)		 T7, T8 Adjust for maximum gain and
symmetrical S-Curve
FM Generator - Modulated RF Radiated Signal
3. 109.0 MHz Open
Output Meter

Across Speaker		 C15 Adjust for maximum.
4. 87.5 MHz Closed L4 Spread or compress coil wind-
ings slightly to raise or lower
frequency. Repeat Steps 3 and 4
5. 108.0 MHz Tune to Signal C1G, C1H Adjust for maximum.
6. 88 MHz Tune to Signal L1, L2 Spread or compress coil wind-
ings slightly to obtain optimum
alignment. Repeat Steps 5 and 6

FM AFC ALIGNMENT (R17 TRIM POT

1. Tune FM dial to a no signal area near the center of the FM Band (98 MHz).
2. With the AFC switch S2 in OFF position, connect a high impedance voltmeter (Triplett 630-NS or equivalent) to S2 pin A1 and
measure the D.C. voltage. Note: Voltemeter chosen must not cause noise in FM Band which would cause incorrect alignment.
3. Next connect voltmeter to S2 pin A2 and adjust R17 trim pot to the same voltage as measured in Step 2. Accuracy of voltage
adjustment to voltage measured in Step 2 should be better than +/- 5%.


CABINET DISASSEMBLY
  1. Remove seven (7) cabinet back screws including
    one (1) located in battery compartment.
  2. Remove Tuning, Treble, Bass and Loudness knobs.
  3. Depress ON/OFF Power knob to the ON position.
    Separate cabinet front from cabinet back at the bottom of
    the cabinet, then carefully lift cabinet front upwards to
    exit ON/OFF knob. (Note: Failure to depress knob
    during this step will cause switch shaft to bend).

TO SERVICE CIRCUIT BOARDS

To simplify servicing, troubleshoot from component side of
circuit board whenever possible, using the component layout
top view. To prevent damage to cabinet front and speaker,
it is suggested that speaker leads be disconnected at speaker 		TO SERVICE CIRCUIT BOARDS, Cont'd

terminals and an 8 Ohm external test speaker be connected to
earphone jack while servicing radio.

  1. Chassis mounting bracket with circuit boards and dial
    cord stringing assembly can be removed from cabinet back
    by removing screws #1 thru #4 (See Illustration)
    For gurthur ease of servicing the bottom side of circuit
    board, disconnect FM antenna lead at whip antenna.
  2. Removal of IF / Audio board from mounting bracket may
    be necessary to remove a defective component from
    certain areas of the circuit board. To remove circuit
    board, remove five (5) screws, #5 thru #9,
    and tilt chassis to expose conductor side of board.

ALIGNMENT PADS

Click image to see full size version:

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REPLACEMENT PARTS LIST - MODEL 7-2880A
CAT. NO.SYM.DESCRIPTION 
 
CAPACITORS
 
EA30X78C1Tuning Capacitor 
EA1BX268C2,10,1875pf, 50V(C)
EA18X201C3,5,615pf, 50V(C)
EA18X186C4,58,59100pf, 50V(C)
EA18X283C7,8,9,14,17820pf, 500V(C)
RT6494C111pf, 50V(C)
EA18X246C1247pf, 50V(C)
EA18X273C135pf, 50V(C)
EA30X26C15Trimmer 
EA18X151C16,5622pf, 50V(C)
EA18X301C19,21,26,27,44.0047MF, 50V(C)
EA31X187C20,31 2.2MF, 50V(E)
EA20X79C22,39220pf, 500V(C)
EA18X299C23,28,30,33,35,43.047MF, 50V(C)
EA18X174C24, 253pf, 50V(C)
EA18X307C29.0022MF, 50V(C)
EA18X203C32390pf, 50V(C)
EA31X211C344.7MF, 35V(E)
RT5045C36,37220MF, 6.3V(E)
EA18X113C388pf, 50V(C)
RT4635C40,41470MF, 6.3V(E)
RT5047C42220MF, 16V(E)
RT3860C45,52.1MF, 50V(P)
EA22X4C46.047MF, 50V(P)
EA31X204 C471MF, 50V(E)
EA23X2C48.1MF, 50V(E)
EA22X17C49.0033MF, 50V(P)
EA22X16C50.033MF, 50V(P)
EA22X6C51,54,55.01MF, 50V(P)
EA31X200C531000MF, 16V(E)
EA18X224C57.001MF, 50V(C)
 
(C) CERAMIC (P) POLY (E) ELECTROLYTIC
 
COILS and TRANSFORMERS
 
EA36X144L1FM Antenna Coil 
RT4722L2FM RF Coil 
RT5370L3Input Choke 
RV2291L4FM Oscillator Coil 
EA35X160L5AM Oscillator Coil 
EA83X128L6AM Antenna 
RT5373L7Choke Coil 
EA61X281T11st FM IF 
EA61X282T22nd FM IF 
EA61X282T33rd FM IF 
EA61X283T41st AM IF 
EA61X284T52nd AM IF 
EA61X285T63rd AM IF 
EA61X162T7FM Det. Primary 
RS6795T8FM Det. Secondary 
EA61X178T94th AM IF 
EA61X286T10AM RF 
EA88X129T11Power Transformer 
 
DIODES and RECTIFIERS
 
EA57X14D1, D2  
RT5637D3  
EA16X193D4  
EA16X144D5  
CAT. NO.SYM.DESCRIPTION
 
POTENTIOMETERS
 
RT2410R17AFC Bias Trim Pot, 50K
EA49X501R24Treble Control, 100K
EA49X501R25Bass Control, 100K
EA49X502R20Volume Control, 50K
CAT. NO.SYM.DESCRIPTION
 
TRANSISTORS and INTEGRATED CIRCUITS
 
Note: When replacing transistors and integrated circuits with
the type specified below, corresponding changes must also be
made.
 
CAT. NO.SYM.COMPONENT CHANGES
 
EA15X7244Q1R2 (470K)
EA15X7244Q2R4 (330K)
EA15X7244Q3R7 (270K)
EA15X7244Q4R12 (270K)
EA15X7244Q5R13 (56K)
EA15X7590Q6 R14 (15K), R21 (39K)
EA15X8447Q7None
EA33X8525IC1R1B Omit
 
MISCELLANEOUS
 
EA36X4B3CF-1Ceramic Filter, 10.7MHz
EA39X328SW1FM/AM Switch
EA39X328SW2AFC Switch
EA39X196SW3Power ON/OFF Switch
EA95X143LS101Speaker 6 1/2", 8 Ohm
EA41X42JK-1Earphone Jack
5-1082MS-1Earphone, 8 Ohm
EA2X50MS-2Whip Antenna w/Sleeve
EA66X48MS-3Power Cord
RT2988MS-4AMP Connector f/Power Cord
EA69X92MS-5Tuning Shaft
EA6X348MS-6Tuning Drum
RT8129MS-7Spring, f/Dial Stringing
RS4675MS-8Pulley
RS2618MS-9Dial Cord
RS4556MS-10Battery Contact, Positive
RT7977MS-11Battery Spring, Negative
EA2X196MS-12Battery Spring, Neg/Pos.
EA9X418MS-13Main Chassis Mtg. Bracket
EA1X751MS-14Cover f/Power Cord Strain Relief
EA3X47MS-15Mylar Washer f/Handle
RT5361MS-16Nut f/Handle End Caps
RV1532MS-17Clip f/Whip Antenna
EA1X752MS-18Screw f/Bracket
EA1X752MS-19Screw f/Tuning Drum
EA1X754MS-20Screw f/Handle Caps
CABINET and APPEARANCE ITEMS
 
EA98X697CA-1Cabinet Front w/ Insert
EA4X799CA-2Insert f/ Cabinet Front
EA98X698CA-3Cabinet Back
EA89X277CA-4Grille w/Holder and Insert
EA9X420CA-5Holder w/ Insert
EA78X92CA-6Handle
EA90X247CA-7Crystal
EA89X276CA-8Escutcheon
EA9X417CA-9Battery Compartment Door
EA6X347CA-10Pointer
CABINET and APPEARANCE ITEMS, Cont'd
 
EA4X798CA-11End Cap f/Handle
EA4X797CA-12Dial Insert
EA4X800CA-13Sleeve F/Whip Antenna
EA43X959CA-14Tuning Knob w/Skirt
EA43X960CA-15ON/OFF Power Knob
EA43X961CA-16Volume Knob w/Skirt
EA43X962CA-17Bass Knob w/Skirt
EA43X962CA-18Treble Knob w/Shirt
EA3X128CA-19Bushing f/Tuning Knob
EA9X419CA-20Cup f/AFC and Band Switch

Replacement parts may be ordered from; General Electric Co., Parts and Accessory Yervice, 1900 Bleecker St., Utica, N.Y. 13501

Note: CA and MS references are for factory use only

IMPORTANT

PERFORM THE FOLLOWING SAFETY CHECKS AFTER SERVICING THIS UNIT:

  1. Remove all externally connected test equipment and wires before safety testing this unit.
  2. Use RT6440 Safety Test Box or construct circuit as shown.
  3. Plug power cord at unit to be tested into Test Receptacle.
  4. Switch unit being tested to ON position.
  5. Connect VTVM across 1K resistor in test circuit. Set meter on high (140V AC) scale to avoid meter damage and touch the following points with Test Probe.
    • Speaker Grille
    • Earphone Jack
    • Whip Antenna
    • Screw in Cord Compartment One (1)

If meter reading indicates less than 3 volts on all test points, set meter to low (3V AC) scale and repeat test.


  1. Any reading greater than two tenths (.2) volt, indicates a pgtential shock hazard. lf this occurs, determine the cause of the leakage, correct the problem, and repeat safety test.


DIAL CORD STRINGING INSTRUCTIONS

To restring dial cord, it will be necessary to remove chassis
from cabinet as outlined in circuit board servicing instructions.

  1. Diol cord length 39 1/4".
  2. Set tuning drum fully counterclockwise
  3. Steps (1 - 11) indicate correct order and direction of dial
    cord installation.
  4. Cement dial cord ends.

GENERAL ELECTRIC MODEL 7-2880A

SERVICE SUPPLEMENT

THIS SUPPLEMENT CONTAINS UPDATED OR ADDITIONAL REPLACEMENT PARTS and SERVICE INFORMATION.


PARTS LIST REVISIONS TO DATE
CORRECT
CAT. NO.		 REF. NO. DESCRIPTION REVISION
EA82X50 MS-2 Whip Antenna Was EA2X50
EA49X520 R17 Trim Pot Was RT2410
EA36X509 L2 FM RF Coil Was RT4722
EA39X254 SW3 Power ON/OFF
Switch		 Was EA39X196
EA36X71 L8 RF Choke Add to Parts List

CORRECTIONS TO SCHEMATIC

C48 is shown as 47MF On the schematic diagram- Please change to 0.1MF as shown in the Parts List

GENERAL ELECTRIC MODEL 7-2880B

SERVICE INFORMATION

This service manual contains the unique replacement parts list and partial schematic for the model 7-2880B AM/FM Portable Radio. The remaining parts, as well as the schematic, wiring diagram, alignment instructions, are the same as those used in the Model 7-288OA. When servicing this model, also refer to service manual 7-2880A, Pub. #37-6000-79.

UNIQUE REPLACEMENT PARTS LIST
CAT. NO. SYMBOL DESCRIPTION
EA98X728 CA-1 Cabinet Back w/External
Antenna Terminals
EA3X264 MS-1 External Antenna Terminal
EA83X135 L6 AM Antenna
EA13X218 R38 2.2 Megohm Resistor/Special
High Voltage Type

NOTE: CA and MS References are for factory use only

Replacement parts may be ordered from: General Electric Company, 1900 Bleecker St., Utica, N.Y. I3501