Belmont Radio Corp. C-10AF21 Schematic

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Product Information:
Model:C-10AF21
Manufacturer:Belmont Radio Corp.

Schematics Content:

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Page 1:

PAGE 18-6 BELMONT

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ELMONT RADIO CORP.

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Page 2:

IMPORTANT- No alignment of
the FM section of this radio should
be attempted unless you are Positive
that the circuits are in need of ad-
justment and you have the neces-

All components used in this radio

BELMONT RADIO CORPA

ALIGNMENT PROCEDURE

FM Band Section LF. and R.F.

A non-metallic alignment tool must be used.

are extremely stable and the tuned
circuits should require no adjust~
ment over a long period of time.

NOTE-The following alignment
is based on the use of the new Simp-
son vacuum tube voltmeter Which
has a "floating ground". In other

Band Switch in FM Position. Dummy Antenna .l de.

MODEL C -lOAFQl

words, the meter, when used as a
vacuum tube volt-meter, can have
both the positive and negative sides
connected to points above ground
and still give true readings.

A standard AM signal generator is

100K OHMS each, from Pin No, 2
of 6AL5 to ground. These resistors
must be matched within 5%. ConA
nect as shown in dotted lines on
schematic diagram. Connect vacuum
tube voltmeter between the mid~

SIGNAL V .
GENERATOR C9rlgle?g{gN voL?rCllfql?hq/-Iiizuggm ADJUSTMENTS 'ro BE MADE ADJUST EoR
FREQUENCY NECT ION TO RADIO

Pin No. 1 ot
10.7 Mc, Use Pin No, 2 of 6ALS _ A Resonance should be
about .1 volt 6 1:55113 and and ground anary of T5 about 3 Volts
Pin No. 1 or
10.7 Mc. Use 6BA6 N0_ 3 and see note "A" Secondary of T5 Resonance should be
about .1 volt about 3 volts
ground
10.7 Mc. Use Pin No. 1 or . Primary and Secondary of T4 Zero.
about 3500 6BA6 No.2 Pm Ng' 2 of EAI; 10.7 m.c. windings Use zero center scale
microvolts and ground an gmun See top and bottom views See note "B"
1047 Mc. Use Pin No. 2 ot . Primary and Secondary of
about 200 HAT., and Pin Ng. Z of 6dAL5 10.7 mx. windings of T3 Resoiance sholllld be
microvolts ground an gm'm See top and bottom views a out 3 vo ts
NOTES ON FM-I. F. ALIGNMENT
NOTE "A" Connect two resistors, point of the resistors and point zz. GENERAL Input signals should be

NOTE "B" If T5 has been tam-
pered with, it is possible that no
crossover point will be found at
hrst. Careful adjustment of both
primary and secondary is necessary.

Cheek pointer so that the right hand edge of the pointer skirt coincides with the
right band edge of marker to the extreme right when iron :ores are all the way out.
For Adjustment, see dial mechanism illustration.

adjusted to give approximately 5
volts. The ratio detector is oper-
ating at a resonable level at this
point and will give the truest in-
dication of correct alignment with
the procedure specified.

SIGNAL vAcUUM TUBE voLT
GENERATOR CQgleglgN AgggaggA ADJUST METER coNNECron ADJUST T0
FREQUENCY To RADIO
100 MC Use FM Antenna ((5658 gslcs' Pin No. 2 of Resonance
?222,011; 30? 0th C52 A'mf sALs andl Ground about s vous

NOTE; If a signal generaxor with me above fundamental
frequency is not available, it is sometimes possible to use harY
moniesA Use extreme care in picking harmonics. An alternate
procedure is to use a local station carrier of known frequency
ro align the FM Band and to use the vacuum tube volt-meter

other screw.

as abov? for resonance indie-rims. A w=ak vm", howaver,
will not produce 3 volts.

NOTE: Connect 300 ohms in series with hot side of generator
and connect to one screw. Connect cold side of generator to

(C)John F. Rider

Page 3:

l PAGE 18-8 BELMONT

MODEL C -lOAF21

ALIGNMENT

The alignment procedure below includes the sensitivities at
the inputs of various stages. All signal input values are based
on an output oi 1/2 watt. This may be measured by disconnect-
ing the speaker voice coil and substituting a 342-ohm resistor
across the secondary winding of the output transformer. A
reading of 1.3 volts AC across this resistor will be approx-
imately equivalent to a l/szatt output with the speaker con-

BELMONT RADIO CORPt

Broadcast Band Section l.F. and R.F.

nectcd. The volume control must be set at maximum. The tone
control must be set for maximum treble. ~
The signal source must be an accurately calibrated signal
generator capable oi suppliog the frequencies designated, modu-
lated 30% with a 400~cycle audio signal. A 400 cycle audio sig-
nal is required for the audio measurement. Variations in sen-
sitivities of plus or minus 25% are usually permissable.

All-LF. ALIGNMENT
Band Switch in AM Posih'on. Tune Sel to 1400 1_(c. Dunnin Antenna .l Mfd4

SIGNAL

g??QES??`F? CQrglefglgN ADJUSTMENTS To BE MADE ADJUST FOR
455 K5- Use A1211; ozf Primary and Secondary of T4 AM windings Maximum Output

:nigga/1m and gmm'ld See.top and bottom views Should be 1/2 watt

455K; Use PgleNAUT; Primary and Secondary of T3 AM windings Maximum output
50 microvolts aid ground See top and bottom views Should be 1/2 watt
400 cycles. Use Harnzngogtfrgylo 1' None Maximum output
28 millivolts and ground Should be 1/2 wart

BROADCAST BAND-ILP. ALIGNMENT

Cher/e painter so that the right band edge of the pointer skirt coincides with 1112
right hand edge of marker to the extreme right when iron cares are all the way out.

For Adjustment, `tee dial mechanism illnlration.

RATIO DEI
one
?3, 2ND LF. TRANS

SIGNAL GENERATOR FREQ. CONNECTION T0 RADIO DUMMY ANTENNA ADJUST
1620 Kc. AM Antenna and Ground 200 mmf. C59 Om gimme:
for maximum
555 Kc. . AM Antenna and Ground 200 mmf. T12 for maximum.
1/2 watt
1620 Kc' C57 and C61 for max
Use 5 microvolts AM Antenna and Ground 200 mmf. 1/2 Watt. See "me
l NOTE: Re-rheck Erst two adjustments after this adjustment because of inter-locking effects

Procedure for disassembly and assembly of dial mechanism

Loosen screws "C" and "D" so that teeth of tape can be pro~
perly meshed with pinion geai to give proper pointer travel.

(C)John F. Rider

Page 4:

BELMONT PAGE 18-9 _

BELMONT ii'ADio coEP. MODEL c-loAFal

the factory.

(C)John F. Rider

RATIO DET.
ELECTRO OUTPUT PHONO PICKUP
LINE CORD LYTIC TRANSFORMER \ SOCKET
SPEAKER PHONO MOTOR
LOOP ANT. SOCKET SOCKET
SOCKET8. EM. ANTENNA TERMINALS chassis-hp view
EXT AM ANT
TUNch sHAFT TUNING BRACKET
T' Z B.c. ANT colL (R) (R)
Tin css QB C55 BAe n Y
wow (C) T
Cease was Sm.
TUNER ADJUSTMENT TONE QONTROL V?LUME CONTROL

With tuner all the way out, dimension uX" should be
11/2 inches. "Y' should be 1-1/16 inches. "X" is from
the end of the slug to edge of the coil winding. Check
these dimensions before R.F. alignment is attempted
of either the AM or FM Band. No slug adjustment
should be necessary since the slugs are properly set at

Page 5:

PAGE 18-10 BELMONT

MODEL C-lOAF'Ql BELMONT RADIO CORP.
REPLACEMENT PARTS LIST
netA No. Part No. Description ursya Ref, Nm p," No, A bums," 3,135,
TUNER PARTS C52 OSD-15459 .25 mfx400 volts 1
Condensers C47, 54 CSD-10760 _1 11112400 volts z
57 1 C55, 56 A-sF-15047 50 mmf, dual, mica 1
C650,65?7,59, -2 -12 18 rimmer cor-1 . pate 5 g? 28 g_sgilggl 510",me Ceramig 5% l
C2 05015695 1000 "151;, 120% ? , 618:19' CSG-12160 91 mmf; ceramic 2
(3375-5014 08015201 1000 mm - +20%-10% ` C16 C-sG-15026 51 mmf, ceramic 1
c4' CSG-1501s ez mmf, 110% 1 Resistors
C12 C-sG-11751 1500 mmf, :20% l R27 A-loA-15001 Volume control (500K)
C10 086-15017 15 mmf, +10% 1 and switch 1
C3 CSG-11484 50 mmf, 110% 1 R51 A-llA-129ss Tone control (500K) and radio-
Cs CSG-11789 10 mmf, :10% 1 phono switch 1
R1 09111'21 22K 1'th' /2 ""1 20% 1 R20 C-9Bl-79 27K ohms 1/ watt 1017 1
R5 C-9B1-17 4700 ohms, /2 watt, 20% l R15 16 C-9B1-4S 68 ohms 1/ watt 107 2
Rs c-9B1-19 10K ohms 1/2 watt, 20% 1 1 - m- we , o
i R24 26,57 C-9Bl-29 470K ohms 1/ watt 2017 5
r R25 09131-502 15 megohms 1/ watt 10?7 1
R9 0931-62 1000 ohms 1/2 watt, 10% 1 s 2 s o
' R19 C-9Bl-23 47K ohms 1/2 watt 2017 l
R46 0913142 22 ohms V wan 10,7 l R12, 55, 45 C-9B1-51 l megohnt, 1/2 watt, 20% 5
T8 B-15D-15027 FM oscillator coil assembly 1 R58 C-9B4-55 270 ohms, 2 watts, 10% 1
T6 134515-15028 FM antenna coil assembly 1 R47 0951-71 5600 ohms, 1/2 watt, 10% 1
T10 B-15C-15029 FM RT. coil assembly 1 R13 C-9B1-15 1000 ohms, 1/2 watt, 20% 1
T9 B-15D-15050 AM oscillator coil assembly 1 R15, 11 0932-15 2200 ohms, 1 watt, 20% 2
T7 B-15E-15051 AM antenna coil assembly 1 cons
T11 B-15C-15052 AM RF. coil assembly 1 .
1.1 MGA-15055 choke coil assembly 1 T3 015A'15009'1 013;",131;'5'iinsifgamfgtfgfgblf
T12 B-15D-12974 _ AM osc, shunt coil assembly l T4 6158450144 Output transformer' Combimb
Mlscellunews tion 455 kc. and 10.7 mc 1
3-208-15555 Band change slide switch 1 T5 C-203-11745-1 Ratio det. coil assembly
B-201-12967 Band change slide switch l L3 A-l6A-13243 Loop loading coil 1
AASB-12997 7 prong, min. tub; sockit 1 L4 B-14MA-11066 Loop antenna>>B.CA Band 1
AASB-15430 9 prong, min. tu e soc et 1 Transformers
N'200'13802 Poggxrinflume and bmka 1 T2 B-12C-15042 Output trans. for speaker 1
A_5A_12508_1 Lead me; l B-12A-1505s Power transformer, primary,
11-51-12509 Pinion gear for lead screw 1 11260 Wd", 105'125 "1115-
A-49A-15447 Tension spring for lead screw 1 1
,42511-15019 core geom., for AM hand 5 Speaker
A-5Mv15020 Insert for core grommet 5 13483-15043 Electrodynamlc speaker, 12"
3-4193Av12594 _ipiral spaing for FM cores 5 less output transformer 1
-2 -12990 ape gui e 1 .
I B-zJ-lsooo Rack, with teeth, with M's'feunews
,4-215-11194 bracket 1 03013-15943 11121 glass 1
A-5M-15741 Pointer l B-SnA-13734 Dial scale 1
52116555274 552,215- screw m mount BSB-15735417 Knob, small, with dot, mahog-
oirlter 1 any 2
MAIN cHissls PARTS Bois-1575757 Knob, large, without dot, mahog-
` any 2
65A, 05B BSC-11629 Electrolytic condenser, dnal, NSA-15003 Switch shaft 1
50.503( AS() volts 1 A-2D-12983 Dctcnr bracket (U shapch on
21 CSG-11754 100 mmf, 20%, ceramic 1 front of set) 1
C57 C-sF5-229 150 mmf, mica 1 A-45D-12954 "U" speed clip 1
C53 CSG-15059 1500 mmf, ceramic 1 A-SSC-12935 Bull Bearing 1
C54 CSG-15060 sl mmf, ceramic 1 A-2D-15004 Switch activator bracket 1
C20, 25, 24, CSD-10785 ,ooo mfxt-oo volts, paper 7 NWA-15801 P1191 1112 assembly 1
30, 51, 45,44 A-46A-11739 Pilot lite, 6-8 volts, T--H 2
C22, C29 CBD-10761 .01 mfr-100 volts, paper 2 A~15C-10717 7 Prong, "lin-- tube Socket <1
015,46 C-sD-10315 .05 mix-100, paper 2 A-15B-10440 s prong, octal, socket 4
C55 A-SC-12154 Electrolytic condenser A-19B-12644 Antenna socket 1
10 mfx 450 volts 1 AWB-15050 FM dipole, Z-screw strip l
C49 CSD-10789 .002 mfxooo volts, paper l AASB-11558 Speaker socket 1
C59,4o C-sG-15201 1000 mmf, ceramic 2 A-19B-124os Phono motor socket 1
C41 ,mC-13151 Electrolytic condenser, 10 mf A-l9B-12170 Phono input socket l
x 50 volts l
C62 C-sJ-11521 .02 mixooo volts 1 RECORD CHANGER
C40 CBD-10770 .05 mfxzoo volts 1 13201-14065 Record changer (Russell C-10)
C50 CSG-11741 550 mmf, ceramic l with P-95 cartridge 1
C42 CSD-11504 .02 mfx200 volts 1 P-95 Crvstal cartridge 1

(C)John F. Rider

Page 6:

BELMONT PAGE 18-11`

MODEL 5C12

BELMONT RXDIO CORP.

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Rider

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