Gamble-Skogmo, Inc. 05RA1-43-7901A Schematic

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Product Information:
Model:05RA1-43-7901A
Manufacturer:Gamble-Skogmo, Inc. (Coronado)

Schematics Content:

Please note: this content is a computer-generated interpretation of the above schematic and is provided only to help assist you in locating this schematic. For the actual text, please consult the schematic above. Thank you.

Page 1:

GAMBLE-SKOGMO PAGE I 11
gn,/I bag A<1',:1=
DRIVE CORD REPLACEMENT
Use a new 1OX38 drive cord assembly or a new length
of cord 46 inches long for the installation, winding
three turns clockwise around the drive shaft with the
turns progressing away from the chassis. After com-
pleting the installation, rotate the drive shaft a few
Iurns to take up the slack in the cord.
POINTER CLAMP
DIAL BRACKET
TENSION
SPRING
DIAL STRING ?
` _, GANG CONDENSER
=\' mm, IN FULLY CLOSED
MODEL o5RA1-LL3 7001A
ELECTRICAL SPECIFICATIONS
Power Supply . ..,.. . .
Frequency Ranges .....
Intermediate Frequency.
Selectivity .... . _ _ _ .
AM Sensitivity
FM Sensitivity
Power Output ........
Loud Speaker
105-125 volts AC 60 cycles 80
watts, 100 watts with record
changer
Broadcast 540-1600 KC
Frequency Modulation 88~108 MC
AM-43 KC broad at 1000 times
signal, measured at 1000 KC
|.F. FM-200 KC broad at 2 times
down
l.F. FM-760 KC broad at 200
times down
(For .5 watt output with external
10 microvolts average
(For .5 watt output)
30 micravolts average
8.5 watts maximum
6.0 watts 10% distortion
12" PM Dynamic
Voice Coil Impedance. .3.2 ohms 400 cycles
Tube and Dial Lamp
Complement
(C).Tohn F. Rider
1 6BA6 AM-FM R-F Amplifier
1 12AT7 FM&AM Osc. & Mixer
1 6BA6 FM-AM 1st I-F Amplifier
1 6BA6 FM 2nd l-F Amplifier
1 6AL5 FM Detector
1 6AV6 Audio Amplifier, AM 2nd
Detector and AVC
2 6K6-GT Audio Output
1 5Y3-GT Rectifier
1 6AV6 Phase Inverter
2 No. 47 Dial Lamps

Page 2:

PAGE 21-12 GAMBLE-SKOGMO
MODEL O>RA1 L13 7901A
ALIGNMENT PROCEDURE
The following ls required for aligning Volume Control Maximum all Adrustments \__/
Calibrated Slgnal at the Test Frequencies as Listed Short Heavy lead
Output Indlcotlng Meter, Nan Metallic Screwdriver Dummy Antennas Allow Chassis and Signal Generator to Heat Up" for Several
1 mf 200 mmf Minutes
SIGNAL GENERATOR
CONNECT
GENERATOR
FREQUENCY OUTPUY 1?
SETTING
THROUGH
DUMMY
ANTENNA
BAND
SWITCH
SETTING
FOR
Pin 7 and Chassis
Broadcast
Rotor Fully Open zna lF rn si saa @ si
lst IF Pn a. sea @ a
si-aaaaasi 1420 kc Exlernalov-I term
mmf Broadcast
R?'?" Fully op" Broadcast Oscillator C33 M?""""'"
1400 Ire External ant term
mm Broadcast
Sat painter ta
1400 kc See Nate A Loop Antenna C-48
Note A It the polnter ls not at
uoo KC on aial reset pointer at alia uoo KC mark on ine aial scale
rna rallaaina equipment ia iaaunea for aligning
FM STAGES
An accurately calibrated signal generator piavnling unmoclulated
signals at the test frequencies listed halaw
Non metallle screwdriver
Zero center scale DC vacuum tube valtmeter having a range of
approximately 3 volts
(lt a xero center scale meter is nat available a standard scale
Discrlm 107 MC Disc Pri
Dummy Antennas and lF loading Resistor 01 mt 300 ohms
and 1000 ohms
vacuum tube voltmeter may be used by reversing the meter connec
tions for negative readings)
Allow chassis and signal generator to warm up for several rmnuras
SIGNAL GENERATOR
SETTING
GENERATOR
OUTPUT TO
THROUGH
DUMMY
BAND
SWITCH
SETTING
GANG
CONDENSER
SETTING
ADJUST
ADJ UST Fon
Note B
6BA6 2|-ld IF Pin
and Chassis
naaai Fu y Open M?><'f"""'
Note A
Deflection
Note B
GBA6 2nd IF Pin
and Chassis
Rotor Fu ly Open
Disc Sec
Nate
Zero Center
Note F
and Chassis
Rotor Fu y Open
lF san Note
and E 9
Maximum
Deflection
Note F
Nate F
and Chassis
6BA6 1st lF Pin
and Chassis
Rotor Fu y Open
Disc Prl
Note A
Maximum
Deflection
Rotor Fu y Open
Dlx Sec
Note C
Zera Center
FM-RF Gang Condenser
terminal
Raoar Fu y Open
Notes A, D & E
Maxim um
Deflection
Rerheck I-F Acliustments in order given
Note H
Disconnect dipole and
connect generator to di-
pole terminals with re-
300 ohms
nalai rally Open
Oscillator C35
Note G
Maximum
Deflection
Disconnect dipole and
sal-man generator to di-
pole terminals with re-
sistor in series
300 ohms
Tune Rotor for Max.
AVC voltage
Maximum
Deflection
Disconnect dipole and
connect generator to di-
pole terminals with re-
sistor in series
300 ohms
Tune Rotor for Max
AVC voltage
Maximum
Deflection
Recheck R>>F and Ose. Adiustmenls in order given
Nora A-real Equipment aannaeians are as given in ina table. Tlia
zero center scale DC vacuum tube valtmeter is to be con-
nected between chassis ground and the AVC line at the
iunclian of resistor ll-22 and condenser C-18 far all ad-
iuannanls except tha disariminator secondary aaiumnano, tar
whiqh See Nate C.
NOTE B-A signal at .1 volt must be ted into the receiver tar this
NOTE C-Disconnect xero center DC vacuum tube valtmeter from
AVC and connect to illnction of R-18 and C>>62. Adjust
tor zero voltage indication.
NOTE D-Before adiusting Pri. core connect 1000 ohm load resistor
across the zna l.r. secondary terminals. lnaur may have
to be increased to .1 van if fenaivai it badly mis-aligned.
NOTE E-Disco|-meet 1000 ohm load resistor from secondary ter-
minals and connect across the Znd |.F. primary terminals.
Input may have ta be increased to .1 volt if receiver is
badly mis~aligned.
NOTE F-Input can be reduced to 10,000 microvolts.
Nor: e-osaillaiai frequency aliava signal frequency.
NOTE H-Remove the 1000 ahm'laad resistor before attempting to
check the R-F and aseillator adiustments.
An All Wave Signal ??narawar wnialfwill Piaviaa an Accurately Connect Radio Chassis to Ground Pan af Signal Generator with a
1400 kc Externalant,term. 200 mint Broadcast Turn Rotor to Max. Output T Output
(C)Jol'm F. Rider

Page 3:

GAMBLE-SKOGMO PAGE 21-13
MODEL O?RA1-l_L3-7901A'
A (AM Loop A/V72
l SHIELD
'/\ /ST ADJ' 5 any AM 'l J 0/scn/M//vAroR
NOTE-T-5 discriminator transformers with Part No. 9A1970 stamped on the can must
be aligned as outlined in this service manual.
Discriminator transformers with Part No. 9A2064 stamped on the can have the primary
adiustment at the top and the secondary adiustment at the bottom.
G2 '1 ...?A)'$.~. >>\ 9o,or Gt" 90,99 E SOCKET VOLTAGE
$ 03 ?\ sign gxntsgiviirz ?""" 6695 Socket voltages are shown an the Schematic diagram
' ' ' L was .
615 A? " ?""??' " Q0A9?,? at the tube socket terminals. All voltages are between
""'"""" Dffwm 535531 the socket terminal and chassis ground. Plate, screen and
cathode voltages were takenz with a 1000 ohm-per-volt
meter with a 300 volt scale used for plate and screen
voltages. Audio grid voltages were read with a vacuum
'ZA _gen MW tube volt-meter. Conditions of measurement are:
?J.. """"?~ Line voltage _ . . . .. . _ . . . . . _ . .... 117 Volts AC
lj 5:36, Signal Input . ....... _ ............ :.:.None
E ' 7; "" A variation of i10% is usually permissible.
(C)John F. Rider

Page 4:

PAGE 21-'I4 GAMBLE-SKOGMO
fum :Z
snow
(C)John F. Rider
.wh ,n M nun .1 :4 `=iw,:} >>~3>>y. Er M.. |m&}}% 'v fi* ?.__.. _ Q' _J
film 'ISM '""'>> ~ "'"'5""" ' "' 7 " !`?>>m '"*"' =-H M.
T_ nm "gg LCA! was
,,.,~.m. ,gpm ,.. / 1->> "-f~ .Y H ,.. ,,, ., may _,Q _"C 3 <,?? ,
,- --l>>'--|-"M--- // . "'"' M -I E M, mum z1m>> gm ?,,f gA<;,,,
mx. nwax, /sr nun A' ?""?"' ur lu lr "' 5' '
ff../mx My. L ,~.m>> mn L-a can mnmssran mm =

Page 5:

_ GAMBLE-SKOGMO PAGE 21:15
REPLACEMENT PARTS LIST
When ordering parts, specify part number, model number and any other perfinenl information
Ref. No. DESCRIPTION von No. ,ee Nm |,E,?R,,,,?,, ,an Nm
CAPACITORS c-52 coooonof, 1-1on1-1, .01 mf 000 v. ...F66103
c-1 Gong Condenser on-1 Pulley .,., ,.,..14A207
c-4 copoeioor, cefonno, 100 nnnf 1 20% __,___A 47X497 c-02 Capacitor, Molded moo, 2700 nnnf i 10%. .47x49z
C-8 Capacilor, Ceramic 47 mmf -L 10% _.__,,._ 47X49B
may C?P?"'?'f C="=""?f ??'""' - ? >>------ 11-101 Reeioeor, Carb:n 1 Megohfn .5 w. ...BB5105
c-21 Puri of 1-5 P.-12 Resistor, Carbon aa Ohms .5 w. ,._, .saaoso
Capacitor, cennnso, as mmf 1- 10% ____,.,_ 47X501 Sf] } Resisfnr, Carbon 56K Ohms .5 w. .___. BB4?63
c-23 coooenof. Dry Eledrolyiir, 5 mf 100 v. ,,__ 45X361 :S Reima" Carb," ,ooo ohm _5 W4 _Nawaz
11-5 Resistor, Curban 100K ohms .5w. ._._.... B85104
czv R-7 Reeseeof, Carbon 10K ornne .5 w. _....as410:1
C_A, 1 11-14 Reoieeof, Carbon 47K Ohms .5 w. , ...,... 110547:
03? CcP"i,?r_ Ceramic] 15 mm, i 10% __ __ _ 47,652 11-16 Resisior, cofhon a91< Ohms 1.0 w ..._.._... C8-$393
_ 11-17 neeaeeof, Carbon 2200 o1nn= .5 w. ,._sss222
' 11-1a 11eeae1of, Carbon 27K Ohms .5 w. . B84273
I 035 C?P\=?i*?f- T'i'""\=f- 1-5 mmf -<>><>>~>> --<-- 2 M439 11-19 Resistor, Wire Wound 3.0 Ohms .5 w, . ...,. . .-zaxzaa
gig C?,p?,d,?,_ 1,,b.,|,,,_ _04 ,,,; 600 V ____ M6403 11-20 11e-mor, were Wound 1400 o1nn- 5.0 w. .... 4ax24z
C38 11-25 vo1-me Control 0 swnon .5 meg, ........ 3011379
c-39 P?" ?' 172 11-20 Resistor, Carbon 15K Ohms .5 w. _-.BB5153
2:13 Part of 1-4 Sig; neeinof, cofbon 10 Mooehfn .5 w. ...BB5106
1 223; copoonof, Dual Maoo, 5050 mmf. .. .... 47X112 $13 Resistor, Carbon 270x Ohms .5 w. ..._.,.. 005274
C-49 Puff ?f T-7 11-30 Rexisior, Carbon 500 ohms 2.0 w. ,...,. ,.D83561
C'5?" sem" 4? '"'45? V~ "X374 R-351 11eoae1of, c.-noon, 470 K Ohms .5 w ...... BB5474
(C)J0h1'1 F. Rider

Page 6:

PAGE 21-16 GAMBLE-SKOGMO
MODEL OSRA1-lr3-790111
REPLACEMENT PARTS LIST (continued)
When ordering parts, specify par# number, model number and any oH1er_per|ir|enf information
lzef. Ne. DESCRIPTION were Ne. ner. Ne. DESCRIPTION Puri ue.
Rm Resisior, Carbon B200 ohms .5 w. ,. .,.. 584822 Dial Breaker Assembly - ~-5~?5X3'
me lzesasrer, cerlserr crsoo Ohms .5 w. __ 584682 Consisting els
R~37 Resistor, Carbon 5600 olrrrrs .5 w. ._ B84562 Tubuiar Rive? __ ._.. 20XI564
Shoulder Rive! .... 2ox15ao
Shoulder lzlrer _ ._ ,,_, zoxlsal
COILS AND TRANSFORMERS
L3 Co", lmemage (FM) M2024 Dial Brazkef ..,,,.. ..., 2 sxlalo
L>>5 clrelre, Insulated .,35A5 s"?P?" B'??k?" R` H' mum?
L-7 cell, Oscillator (FM) ...... 94.2023 C?"'i'""? ?"
L-s Choke (FM Mixer Plate) 35A7 Did B'??k?' A"?"`b'Y MSX"
l.1 Ist lf. Coil Assembly lFM> 9A2043 "'"'?""' SM " """x5?
1,1 1sr lf. Coil Assembly (AM) 9/12029 SP""' """ "" 2 "5"
T>>3 Qrrrl l_F_ Coil Asserrrlsly (FM) 9A2030 ugh' s"i?'d """X8?
1-4 2nd lm. Coil Asserrrlrly (AM) 9A2o42 Di?' C`I?" ""`5BX7'6
1.5 Discriminutor cell Assembly 9A2oe4
T~6 oleele Aniennu Asserrrbly ,_...___ 9A2004 MISCELLANEOUS
1_7 ` ,,B,. Range Loop Amen" Ammbry _>___'__ ,AWN eerrd clrerrge srrlrslr ,.........,,..,,.., ..... 2 A404
1-s Power Transformer ...,._.._..,,. ,,.. 5 :mea P"?"? M?'?' 5?"'?' ~~-' "?'~ 3 "'3?'
T_, omg, ,mmhrmer _ _ "XM Phono Socket (Single Parr), _ _ _ _ _ _ .:lAao5
Molded Octal Tube Socket _______,.______ .____ J A435
Tube Socket (miniature, for AMrFM Converter) ,.., ..... 3 A436
mm- AND TUN|NG PARTS Tube seeker lMlrrse1rrre> ______._____.___.., _.__. a A439
R""*'?' G'?'"'"?" img Gong Condenser ?"?7 Pilot Lighr Socket Assembly ,_.. __.__ 7 A215
DH" Cvfd A?=e>>1\b|y ~-~-- - .IOXGB 12" PM. Speaker ._ .... 12A5o2
"C" Washer (Drive slrrrm .. l9Xi92 Line Cord as Plug Assembly ..___. .... 1 sxsur
orare Shaft ______.,.,._._ zaxsoo rrrlre Shield (AM>>FM Converier) ,... :lzxaes
nrlre cord lerrslerr Spring ,_ ,_.. 2BX\13 Tube slrlela (Miniafure) ,...... .... 3 2x:l9o
(C)Johr1 F. Rider

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