Philco 48-1000 User manual

PHILCO SERVICE
.SERVICE
Phiico Television Receiver, Model 48-1000

MODEL48-1 000
SPECIFICATIONS
Description:
Ten-inch, direct-view,table-model,
televisionreceiver.
FrequencyRange:
Television broadcast channels 1
through 13.
Number of Tubes:
Twenty-six.
Antenna:
Provisions fortwo antennas, one
each forthelowand high bands.
Transmission Line:
300-ohm balanced type.
ChannelTuning:
Eight-position Turret - Tuner, with
snap-intypecoils forthe designated
channels forthe televisionbroadcast-
ing area in which the receiver isto
be used.
Intermediate Frequencies:
Video carrier—26.6 megacycles.
Audio carrier—22.1 megacycles.
Operating Voltage:
110—120 volts, 60 cycles, a.c.
Power Consumption:
275 watts.
Power Supplies:
325 volts d.c. at300 ma., 7300 volts
d.c. at200 microamperes(approx.).
Audio Detector:
Ratio-type FM detector.
A.F.C.:
Automatic tuningwithelectronic
control.
A.V.C.J
Automatic levelcontrol of picture
and sound.
Tone Control:
Continuouslyvariable,treble to
bass.
BassCompensation:
Tapon volumecontrol.
Audio Output:
2.5 watts.
Speaker:
Six-inch, permanent-magnet,
namic, 3.2-ohm voicecoil.
dy-
Picture Presentation:
Ten-inch directview,magnetic(par-
tially permanentmagnet) focus, mag-
neticdeflection.
D-C Restoration:
1N34 crystal diode.
Deflection Generation:
Hard-tube oscillators.
2
COPYRIGHT, 1947, PHILCO CORPORATION

MODEL 48-1000
GENERAL DESCRIPTION
PhilcoTelevisionReceiver,Model48-1000,
is a wide-bandsuperheterodynevideoreceiver
combinedwith anFM audioreceiver,incorporat-
ingthe mostmoderncircuitdevices.Outstand-
ing circuitadvancesinclude the PhilcoPrecision
ChannelSelector,whichgives greater selectivity
and higher gain inthe radio frequency circuits,
automatictuningwithelectroniccontrol,which
counteracts any frequency drift ofthe incoming
signal, and automaticcontrol of picture and
sound,whichovercomes the fading of high-fre-
quency signals.Theseadvancements,combined
withprecisionconstruction,reduce the number
of operatingcontrols tofive, thussimplifying the
use ofthe receiver.
INSTALLATION AND OPERATION
CHOOSING A LOCATION FORTHE RECEIVER
In selectinglocations forthe receiver and
antenna, the owner ofthe televisionreceiver will
decide the exactlocation forthe installation.
However, the television serviceman canbeof
assistance tothe owner inthe selection ofa good
location, andcan thereby do much to promote
ownersatisfaction.Certainfactorsshould be
brought tothe owner'sattention in choosing the
receiver location.These factors include:
Room Lighting
The roomneed notbe dark to view the
televisionprogram; a smallamount of general
lighting is evendesirable. The receivershould
be so located thatsunlight or light fromlamps
will not falldirectlyupon the picturescreen, or
cause glare or reflections inthe eyes ofthe audi-
ence. It is advantageous to be ableeasily to
darken the roomsomewhat for viewing of day-
time programs. The picture will appearclearer
if the receiver isnot placednear a window, so
thatdaylight will notbe directly in back of,or
on eitherside ofthe picturescreen.
SeatingSpace
The picture canbe viewedcomfortably, by
mostpeople, from a distance of between fiveand
fifteen feet. For thisreason, it is well to locate
the receiver so that an area of about five feet by
fifteen feet is available, or easilyarranged,direct-
ly in front ofthe receiver. In this way, guests
may be accomodatedmostconveniently.
Power Facilities
The chosenlocationshouldprovide easy
access toan electrical outlet, andif convenient,
a groundingpoint.
Interference Sources
Although thenew Philco television circuits
arenot easilydisturbed by outsideelectrical
disturbances, itis advisable,wherepossible, to
locate the receiver andthe transmissionline at
a distancefromelevators,largeelectricmotors
and similarsources of possibleinterference.
Alternate Receiver Location
If it appearsthatthere aretwo possible
locations forthe receiver,considerationshould
be given to providingfacilities in case the owner
wishes to move the receiver ata later date.
Usually,thisrequirement canbemetby making
the transmissionline long enough to reach the
alternatelocation and coiling the excessline at
someconvenient point along the lead-inroute.
Figure 1 illustratessome ofthe items tobe con-
sidered in choosing the location forthe receiver.
WINDOW
/DOOR
CLEAR
AREA
FIGURE 1. RECEIVER LOCATION.

MODEL48-1000
TELEVISION ANTENNAS
When the location forthe receiver has been
selected, the antennashould be installed. The
antenna isa veryimportantpart ofthe installa-
tion andthe following factors enter into the
installation problem.
Very-high-frequency radiowaves,such as
those used in television,havesomecharacteristics
different from thoseused in ordinarybroadcast-
ing. The mostimportant difference isthe straight-
line travel of television waves,called line-of-sight
propagation. The televisionbroadcastdoes not
follow the curvature ofthe earth'ssurface so
thatreliablereceptionbeyond the horizon isnot
possible. The broadcast canbe intercepted bya
hill or otherobstruction,thuspreventingrecep-
tion bya receiverlocatedbehindsuch an obstruc-
tion. For thisreason, itis necessary to locate
the antenna as high as possibleabovesurround-
ing objects.Anotherpeculiarity of television
waves is thatthey reflect from solidobjects. By
thisaction, a televisionsignal can reach a receiv-
ing aerial from morethan one direction, often
resulting in reception ofthe same signal from
the same broadcastingstation at slightly differ-
ent times.This effect producesmultiplepictures,
or ghosts, onthe televisionscreen.Reception by
multiplesignalpathsmusttherefore be avoided.
Televisionreceptionrequires theuseof
special antennas. The mostcommontype isthe
half-wave dipole,consisting oftwo rods,each
DIPOLE KIT
HIGH FREQUENCY 45-1523
LOW FREQUENCY 45-1525
AERIALFROM KIT
45-1525
HOLES SHOWN IN PAIRS FOR
CHANNELNUMBERS AS SHOWN
1,2, 3.45,6
.ERIAL FROM KIT
45-1523
7 12
813
HOLES FOR CHANNEL 127
NUMBERS AS SHOWN 138
9
10
TP-2635
FIGURE 3. DIPOLE AND REFLECTORAERIAL.
a quarter-wavelong,separated byan insulating
member. Seefigure2. This type of antenna is
bi-directional since it receivesequallywell in
eitherdirection at right angles tothe line ofthe
rods, but receivesverypoorly in eitherdirection
in linewith the rods.Such an antenna canbe
usedwhere itis desired to receive from two
directions, and wherereflections, or ghosts do
not interferewithsuchreception. Where inter-
ference occurs, itis necessary tousea moredirec-
tionalantenna,such asa dipole-with-reflector,
shown infigure3. Such an antennareceivesbest
only from the directionindicated, and therefore
tends to suppressreflectionsarriving atthean-
tenna from otherthan the direction in which the
antenna is aimed. Moreover, the dipole-with-
reflector will provide a strongerreceivedsignal.
The length ofthe sections ofthe dipole
antenna is basedupon free-space wavelengths.
Thislength canbe convertedinto the physical
length byuseofthe following formula:
Length in feet
of each
Vi-wave rod
234
Television channel frequency in megacycles
TP-2629
FIGURE 2. SIMPLEDIPOLEAERIAL.
The followingtableshows the length ofthe
dipole(consisting oftwo quarter-waverods)
andthe reflector for eachtelevisionchannel.

MODEL 48-1000
Channel
Number
1
2
3
4
5
6
7
8
9
10
11
12
Frequency
(me.)
44-50
54-60
60-66
66-72
76-82
82-88
174-180
180-186
186-192
192-198
198-204
204-210
Dipole
Length
(in feet)
10.00
8.20
7.50
6.80
5.90
5.50
2.65
2.56
2.48
2.40
2.33
2.26
Reflector
Length
(in feet)
10.50
8.60
7.85
7.15
6.20
5.80
2.78
2.69
2.60
2.52
2.44
2.37
FLAT ROOF SLOPING ROOF PEAKED ROOF
BOTH
STAGGERED SPLICE OF
TRANSMISSION LINE
FIGURE 5.
TP-2634
RECEIVER-AERIAL CONNECTIONS.
TP-2631
FIGURE 4. AERIAL-MASTINSTALLATION.
Antennas canbe constructedwhichoperate
with fair efficiency overeither thelowor high
band ofthe televisionchannels,making itun-
necessary to employ "cut" dipolesexcept in
installationswheresignalstrength is abnormally
low, or where interference or reflections areex-
ceptionallytroublesome.
Transmissionlines forusein television re-
ception are specifically designed to match the
antenna. For thisreason, itis necessary to employ
the type of line specified forthe receiver. For
all 1948 ModelPhilcoTelevisionReceivers, 300-
ohm parallel-wireline,Part No. 45-1514, is re-
quired.Installation of thislineshould be care-
fully made,withspecialregard to properly secur-
ingthe line at intervals ofnot morethanthree
feet, to preventvibration or othertypes of damage
tothe line.Connections tothe receiver are made
by means ofa four-prong plug and jack. See
figure5.
Televisionantennainstallationsmust be
madewithspecialemphasisupon the following
points.
1. The antennamust be placed ina high
position,clear ofall obstructions, andin line-of-
sight ofthe transmittingstation.
2. The antennamust be properlyaimed to
obtainmaximumsignalstrength and freedom
from echoes and interference.
3.In areas oflow signalstrength, itmaybe
necessary tousean antenna of specific length to
obtainbestresults.

MODEL 48-1 000
4. Installation oftwo antennas, oneforthe
low-frequency band andoneforthe high-fre-
quencyband, maybe necessarywhere signal
strength or interferenceconditions are unfavor-
able.
The followingPhilcoantennas, specifically
designed foruse withtelevisionreceivers, are
available inkit form.
The PhilcoLow-FrequencyAerialKit,Part
No. 45-1525 consists ofa dipoledesigned for
channel No.3,75 feet of 300-ohm transmission
line, and window-sillmountinghardware.
The Philco High-Frequency AerialKit,Part
No. 45-1523consists ofa dipole designed for
channel No.9,75 feet of 300-ohmtransmission
line and window-sill mounting hardware.
The PhilcoAerialMastKit,Part No. 45-1465
contains the necessaryhardware to providemast-
mounting for televisionantennas.
The PhilcoAll-WaveAerialKit,Part No.
45-1522 contains a specialbroad-banddipole
array, 75 feet of 300-ohm transmissionline and
hardware for mast-mountingwhenusedwith the
Mast Kit. The All-Wave Antenna isnot designed
for use with a reflector.
The PhilcoLow-FrequencyReflectorKit,
Part No. 45-1526 contains a reflector dipole de-
signed for channel No.2, adjustablespacer-
supportbar, and otherhardware for mast-mount-
ing whenusedwith the Low-FrequencyAerial
Kitandthe AerialMastKit.
The Philco High-FrequencyReflectorKit,
Part No. 45-1524 contains a reflector dipole de-
signed for channel No.8, adjustablespacer-
supportbar, and otherhardware for mast-mount-
ing whenusedwith the High-FrequencyAerial
Kitandthe AerialMastKit.
Dipole and reflectorlengths as supplied in
the kits are chosen to provide a maximum of
flexibilityin reception of different channels,with
a minimum of cutting.Furtherinformation and
installationdata for theseantennas are supplied
witheachkit.
PREPARING THE RECEIVER
FORUSE
Wheneverpossible, the receivershould be
unpacked and prepared foruseinthe dealer's
shop, so that operation maybe checked under
knownconditions of antenna,interference,power,
and similarfactors.
The receiver is shippedwith all tubes in
place,except the picture-tubeassembly.Unpack
the receivercarefully, and inspect the chassis and
cabinet tobe surethat no damage has been in-
curred in shipment.Remove the protectivecover
from back ofthe receiver and check for loose
tubes, and damagedparts.Unpack the picture
tube and inspect for damage. To install the pic-
ture tube, first remove the receiverchassis from
the cabinet.Carefullyinstall the picture-tube
assembly inthe cabinet as shown infigure6,and
tighten the threeboltssecurely.
TP-2946
FIGURE 6. PICTURE-TUBEASSEMBLY INSTALLATION.
Insert the coils inthe PhilcoPrecisionChan-
nel Selector, as shown infigure7. Note the posi-
tion ofthe selector and insert the coils in numer-
ical channelsequence,correspondingwith the
eightpositions ofthe channelselectorswitch.
Replace the chassis inthe cabinet, andse-
curely tighten the mountingbolts.Connect the
deflection-assembly plug, the picture-tubeplug,
andthe high-voltagecable.
Insert a test lead intheAFC testjack(J200)
inthe frontcorner ofthe chassis for connection

MODEL 48-1000
FIGURE 7.
TP-2756
TUNER-TURRET COIL INSERTION.
to a 20,000-ohms-per-volt voltmeter and replace
the coverover the rear ofthe cabinet.Thistest
lead will be used for adjusting the oscillatorcoil.
Plug the antennatransmission line into the
antenna jack onthe rear ofthe chassis and con-
nect the receiver toa source of 115-volt, 60-cycle
alternatingcurrent.
CONTROLS AND ADJUSTMENTS
Fivecontrolknobs,locateddirectlybelow
the viewingscreen ofthe receiver,provide all
the controls for normaloperation ofthe receiver.
These five controls arethe onlyones which will
be operated bythe user after the receiver has
beenplaced in service. All otheradjustments
must be made bya qualifiedtelevisionserviceman.
Thefive operatingcontrolsshown infigure8 and
identified onthe schematicdiagram,are, from
left to right:
1. CHANNELSELECTOR. This knob ro-
tates the Philco PrecisionChannelSelector,con-
necting the correctcoils into the circuits ofthe
selector, and connecting the correct antenna for
the selectedchannel. Turn thisknob tothe chan-
nelofa stationwhich is broadcasting.
2. OFF-ON-TONE CONTROL. This knob
controls SlOO and R214,turning onthesetinthe
first position of clockwiserotation, and adjusting
the bass and treble response inthe remainder of
the rotation. Turn thisknobuntil thesetis
switched on.
3. VOLUME CONTROL. This knoboper-
atesR213,adjusting the amplification ofthe audio
signal. Ithasno effect upon the videosignal.
Adjust for desired volume.
4. BACKGROUND CONTROL. This knob
operatesR433,regulating the average d-c bias of
the picturetube, and affects only the videooutput.
Turn thiscontrolclockwiseuntil the picture-tube
screen is faintlyilluminated.
5. CONTRAST CONTROL. Thisknob ad-
justs R431,controlling the amplification ofthe
videosignal,thuscontrolling the extent of gray
range inthe picture. Turn thiscontrolclockwise
until a satisfactory picture is obtained.
In addition tothe operatingcontrols, the
serviceman will use twelveknurledknobs, or
screwdriver-operated controls for adjusting the
various circuitswhich affect the overallperform-
ance ofthe receiver. Sixof thesecontrols are
located onthe front ofthe receiverbehind the
droppanel as shown infigure8. Fourcontrols
are located onthe rear ofthe receiverchassis.
One control is locatednext tothe channelselector
onthe front ofthe receiver, andone control is
located ontopofthe chassis. The drop-panel
controls have the following functions:
FOCUS VERT. HOR. HEIGHT
HOLD HOLD L<». ^".'
FIGURE 8. DROP-PANEL ADJUSTMENTS.
TP-2V45

MODEL 48-1000
6. FOCUS — adjusts R546,controlling the
amount of current flowinginthe focusing coil,
L502. Adjustthiscontrol to obtainsharp fine
sweep lines inthe picture.
7. VERTICAL HOLD—adjusts R517, regu-
lating the free-running frequency ofthe vertical-
sweep generator.Adjustthis control to stop any
vertical shifting ofthe picture.
8. HORIZONTAL HOLD — adjustsR532,
regulating the free-running frequency ofthe
horizontal-sweep generator. Adjustthis control
to stop any horizontalmovement ofthe picture.
9. HEIGHT—adjusts R513, controlling the
amount of amplification ofthe verticalsweep,
and thereforegoverning the verticaldimension
of the picture onthe screen.Adjust the control
until the picture is largeenoughvertically to just
fillthe picture frame.
10. VERTICAL LINEARITY—adjusts R522,
controlling the linearity ofthe verticalsweep by
changing the operatingcharacteristics ofthe ver-
tical-sweep outputtube.Adjustthiscontrol to
obtain a symmetricaltestpattern inthe vertical
plane.
11. HORIZONTALLINEARITY — adjusts
R540, controlling the action ofthe horizontal-
sweepcontroltube whichgoverns the linearity
of the horizontalsweep.Adjustthiscontrol to
obtain a symmetricaltestpattern inthe horizontal
plane.
HOR.
CENT.
VERT
CENT.
WIDTH
BEAM
BENDER
TP-2948
FIGURE 9. ADJUSTMENTS ON REAR OF RECEIVER
CHASSIS.
The controls onthe rear ofthe chassis as
shown infigure9, are:
12. BEAMBENDER — adjusts R525,con-
trolling the amount of current flowinginthe
beam-bender coilL501.Adjustthiscontrol to
obtain the brightest possible picture, lowering
the backgroundcontrol as necessary to determine
the properposition ofthe beam-bendercontrol.
Nextmove the beam-bendercoilforward and
backwardvery slightly onthe picture-tubeneck
and rotateslightlyuntil the brightestpossible
pictureshowsthat the coil is properlylocated.
13. WIDTH — adjusts L503A and L503B,
regulating the amount of deflectioncurrent flow-
inginthe horizontal-deflectioncoils,therebycon-
trolling the horizontaldimension ofthe picture.
Adjust this control to obtain a picture wide
enough to just fillthe picture frame.
14. VERTICAL CENTERING — adjusts
R524, controlling the amount and polarity ofthe
d-c centeringcurrent flowinginthe vertical de-
flection coils.Adjustingthiscontrol will move
the entirepicture upor down.
15. HORIZONTAL CENTERING—adjusts
R544, controlling the amount and polarity ofthe
d-c centeringcurrent flowinginthe horizontal-
deflection coils.Adjustingthiscontrolwillmove
the entire picture tothe left or right.
16. A-V-C AMPLIFIER—this control ison
thetopofthe chassis and adjustsR423,regulating
the amount of amplificationapplied tothe a-v-c
signal. This control has beenadjusted atthe fac-
tory and should notbe readjustedunlesscircuit
componentshavebeenaltered.Instructions for
adjustment are includedwith the alignmentpro-
cedure.
17. LOCAL - OSCILLATOR - COILTRIM-
MER— This control is located onthe front of
the chassis andis accessible through the front
panel after removing the channelselectorknob
and dial. This control adjusts the core ofthe
particularoscillatorcoil inuseforthe channel
beingreceived. With a televisionsoundsignal
being received, adjustthis control to obtain a
reading of0 onthe 20,000-ohms-per-volt volt-
meter,previouslyconnected totheAFC testjack.
Thissettingshouldalsoresult inthe clearest
and loudestsoundsignal.Makethisadjustment
for eachchannel. Operation ofthe receiver
should be checkedagainstanotherreceiver if
there isany indication of incorrectoperation. The
receiver isnow ready tobe installed inthe home.
Extreme careshould be exercised in transporting
the receiverfrom the shop tothe home, so that
the receiverwill notbe damaged, andso that
final adjustments inthe home canbe minimized.
Leave theAFC testleadconnected inthe receiver
until the homeinstallation is completed.

MODEL 48-1000
INSTALLING THE RECEIVER
Place the receiver inthe preparedlocation
and connect ittothe antenna and powersource.
Turn onthe receiver and make any necessary
readjustments ofthe controls.
The aiming ofthe antennashould nowbe
checked. With the receiveroperating, the antenna
should be rotated byan assistant, while the service-
man carefully observes the appearance ofthe
picture, andthe voltagedeveloped attheAVC
test jack (J401). Useofan intercommunicating
system betwen the serviceman andhis assistant
is recommended, andto avoiderroneousresults,
the assistantshouldmoveawayfrom the aerial
duringeachpositioncheck. The antennashould
be placed inthe positionwhichgives the best
compromisebetweenmaximumsignal strength
(highestvoltage attheAVC test jack) andab-
sence of echoes or interferencepatterns. In cases
wherereception is desired from twoor more
stations inthe samefrequencyband but which
are located in different directionsfrom the re
ceiver, a compromise maybe necessary,aiming
the antenna forthe bestaveragesignal. If separ-
atelowand high-bandantennas are used,each
antenna must be aimedseparately. Seefigure10.
CB3
/£.
\O
TP-2635
FIGURE 10. AIMING THE AERIAL.
The local-oscillator-coiltrimmershould now
be readjusted for eachchannelinstalled inthe
receiver, andany other controls readjusted to
t^t obtain the bestpossibleperformance.(Thehold
controlsshould be readjusted onthe weakest
station tobe received.) The receiver isnow ready
for usebythe owner, andthe serviceman should
explain and demonstrate the operation ofthefive
operatingcontrols,using the owners' "Users
Instructions",which is packedwith the receiver.
The ownershould be cautionedagainsttamper-
ing with the othercontrols, and againstremoving
the coverfrom the back ofthe cabinet.Invite
questionsfrom the owner andbe sure that the
operating instructions are understood by those
who will operate the receiver.
The followingillustrationsshow the results
of the morecommonincorrectadjustments of
controls andmay make it easier forthe customer
to operate the receiver.
TP-3065
FIGURE 11. BACKGROUND TOO HIGH.
TP-IV69
FIGURE 12. HORIZONTALHOLD IMPROPERLY ADJUSTED.

MODEL 48-1000
TP-1974
FIGURE 13. VERTICAL HOLD IMPROPERLYADJUSTED.
TP-1963
FIGURE 14. FOCUS CONTROL IMPROPERLYADJUSTED.
CIRCUIT DESCRIPTION
The Model 48-1000 receiverschematic is
dividedinto five majorsections for easycircuit
analysis. Thesesections arethe Radio-Frequency
Section, the VideoSection, the AudioSection,
the SweepSection, andthe Power-SuppliesSec-
tion. This division is clearlyshown inthe block
diagram, figure 16, whichalsoindicates the inter-
relation ofthe sections. A completeschematic
diagram forthe receiver is shown infigure27.
RADIO-FREQUENCY SECTION
To providemaximumsensitivity and selec-
tivity, consistentwith a six-megacyclepassband
inther-f section, a separate setof coils is used
for each ofthe thirteentelevisionchannels. The
antennacoil andther-f amplifiercoil for each
channel are built asan assembly, asarethe mixer
coil and the local-oscillatorcoil, so that two as-
semblies comprise a setof coils foranyone
televisionbroadcastchannel. Any eight of these
thirteensets of coils maybe easily installed in
the PhilcoPrecisionChannelSelector,without
soldering or wiring.Since a maximum of only
seventelevisionbroadcastingstations is alloted to
any one area, the PhilcoPrecisionChannelSelec-
toris adaptable foruseinany portion ofthe
country. Provision is made for separatehigh-band
and low-bandantennas forusein localitieswhere
signalstrength or otherconsiderationsmakesuch
an arrangementnecessary.
When correctantenna,antennacoil, r-f coil,
local-oscillatorcoil and mixercoilhavebeen
connected into the circuit by setting the channel
selectorknob, the signal from the antenna is
transferred tother-f amplifiercircuit. Here the
signal is amplified and resistancecoupled into
the mixercircuit,where it heterodyneswith the
output from the local oscillator .to produce the
desiredvideo and audiointermediatefrequencies.
The localoscillatorcomponents are especially
TP-2665-G
FIGURE 15. RADIO-FREQUENCY SECTION,
SCHEMATIC DIAGRAM.
10