Philco 37-640 User manual

• • • • • • • • • • • • • • morM.37-61/.0
FOR MEMBERSOF
RADIO MANUFACTURERS
SERVICE SERVICEBULLETIN
No. 153
SERVICE DATA
Model 37-640 is a 7 tube superheterodyne receiver for operation
on alternating current, having three tuning ranges, covering standard
broadcast and short-wave frequencies. The chassis is constructed
in three basic assembly units, concentrating the R. F., I. F. and
Audio Output circuits in individual units.
The circuit consists of the "PHILCO FOREIGN TUNING
SYSTEM"-controlled by the range switch - providing maximum
sensitivity and noise reduction, when used with the PHILCO
HIGH EFFICIENCY AERIAL. One stage of radio frequency
amplification which increases the signal to noise ratio, Automatic
Bass Compensation in the volume control circuit, Shadow Tuning, a
separate diode circuit for the Automatic Volume Control and a
push-pull pentode audio output circuit are also incorporated in this
receiver .
Aerial Connections
The Philco High Efficiency Aerial is recommended, ~or use wit_h
this receiver to obtain maximum performance . A terminal panel 1s
provided at 'the rear of the ch~ssis for connecting _the _aerial. This
panel contains four screw terminals and a connecting link.
When using the PHILCO HIGH EFFICIENCY AERIAL connect
the red and black leads of the Aerial transmission line (lead-in) to
terminals 1 and 2 respectively and the ground lead to terminal 3.
The connector link should be across terminals 3 and 4.
If a temporary aerial and ground is used shift the connecting link
to rest across terminals 2 and 3 and connect the aerial and ground
to terminals 1 and 3 respectively .
REMOVING SWITCH AND COIL ASSEMBLIES
FROM R. F. UNIT
Remove the center mounting screw on the rear of the R. F. unit.
Then lift the rear of the unit and push forward until the rubber
mounting grommet , on each side of the unit, clear ·the mounting
slots . The unit is then lifted far enough from the chassis for removal
of the two screws holding the selector switch indexing plate and
shaft (front of the unit) then pull shaft straight out. Removal of
the volume control shaft is also necessary .
IMPORTANT - When selector switch shaft is replaced, care
should be taken to have all wafer rotors in the same position so that
index projection on the end of shaft will slide freely into notched
hole in wafer rotors . Never force shaft into rotors.
AERIAL SWITCH AND COIL ASSEMBLY.
FIRST SECTION FROM REAR OF UNIT
a. Remove screw holding shield plate to unit base. This screw
is located in the right hand corner of shield plate , facing rear under-
side of chassis.
b. Unsolder the leads connecting the range switch to the aerial
panel and I. F. terminal panel; tubular condenser @ to the tuning
conde nser stator plate and ground lead from assembly shield to unit
frame-lift assembly straight out of unit.
R. F. AMPLIFIER ASSEMBLY, CENTER SECTION
a. Remove screw holding shield plate to unit base.
b. Unsolder the leads connecting the range switch to I. F. terminal
panel and 6K7G plate socket contact, tubular condenser @ to the
tuning condenser housing, selector switch contact (D2) to the tuning
condenser stator plates, tubular condense r @ to shield ground lug
and shield to R. F. unit base. The amplifier assembly may then
be removed.
OS(;:ILLATOR SWITCH AND COIL ASSEMBLY.
THIRD SECTION FROM REAR OF UNIT
a. The oscillator assembly may now be removed by unscrewing
the four screws holding shield to R. F. base. These screws are
located on each side of the R. F. base.
b. Unsolder the leads connecting range switch to the 6K7G socket
contacts and terminal panel in the I. F. unit, condenser @ lead
from tuning condenser housing and lead connecting selector switch
to the tuning condenser stator plates. Then unsolder wires con-
necting selector switch to electrolytic condenser @ and 6A8G
socket contacts.
Parts are replaced by following the above procedure in the reverse
order. Electrical Specifications
Voltage Rating : 115 A. C.
Frequency Rating: 50 to 60 cycle.
For 25 to 40 cycle operation use Power Transformer marked w:th
asterisk in parts Iist.
Power Consumption: 80 watts .
Type and Number of Tubes: 2 type 6K7G - R. F. and I. F .
Amplifier; 1 type 6A8G-Det. Oscillator; 1 type 6Q7G-2nd Det.,
1st Audio, A. V. C.; 2 type 6F6G- Push-pull Output; 1 type
5Y4G-Rectifier.
Undistorted Output: 5 watts.
Intermediate Frequency: 470 K. C.
Tuning Ranges: Three . Range 1- 530 to 1720 K. C.
2.3 to 7.4 M. C. Range 3- 7.35 to 22 M. C.
Speakers: K-34 B Cabinet.
H-25 X-MX Cabinet.
Range 2-'-
POWER TRANSFORMER DATA
Schematic
235V. ?5V. z DET·lsAUDIO Lead A.C. Current Circuit Color Resist•
.L ND. · T. Number Volta ance
R.F.
SK1G ~0:11GQ
1G - ~120-- ..- Pri.-- White 3oh.;.
V 11~ooB2o: -;:- -;;-;~ ~:.-- -;~:- .1oh:
._________ •_.,_·v~·Ar- ~ ~
0 - - - - - --- H;;i;--- 70 oh:
~\r:b .l ·V.-A.C. 5-7 670 L~ Voltage Yellow 75 ohms
=:::....._________________ Sec.
FIil, I- Socket ·Voltaaes
Measured from Underside of Chassis
The volt ages indicated by arrows were measured with a Philco 025
Circuit Tester which contains a voltmeter having a re8istance of 1000
ohms per volt. Volume Control at minimum, range switch in broadcast
position, line voltage 11.5A. C.
8-9
Center
Top of
5-7
Yellcw
Green
6.7 3.0A ~~bes Black . I ohm
Copyright 1936, Philco Radio & Television Corporation
Fig. 2-Speaker Wiring
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No. 253
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PHILCO Service Bulletin
-- ------- - ----- -- - -- - -- - - - - -- --- ---- -- - -- - -- ---- -- --- 7-- -- ---- -- - --- - ----,
,'/ ~ TUNING CONDENSlR ,/ ~ ,/
/ _({K7GI m ,.filh D2 - /~L::_6A8G/
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86 - ...... 1\4
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2-TAP '- 3 1 - 2
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BROADCAST
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Fig. 3-Schematic Diagram
Model 37-640
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30:,..-01
DIRECTION OF
ROTATION F'ROM
REARor SWITCH.
PageZ
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ALL SWITCHESSHOWNIN POSITION
NO.l(BROADCAST).
SOLID A.RE.AINDICATES REAR or
SWITCH WAFER.
SHADEDAREAINDICATES FRONT
OF SWITCH WAFER.
LUT[llS INDICATE POSITION
or SWITCH WAFERS FROM
REAR or CHASSIS.
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No. 253 PHILCO Service Bulletin Page3
6 FSGTUBE BFBGTUBE BQ7GTUBE
OUTPUT OUTPUT 2ND DET.,l5T AUDIO
Fig. 4- Base View
Replacement Parts-Model 37-640
Schem. Part List Schorn. Part List Schorn. Part List
No. Description No. Price No. De,cription No. Price No. Description No. Price
1 Antenna Transformer (Broadcast). 32-2108 so.so 49 Resistor (490000 ohms½ watt). 33-449339 $0.20 Indicator Bracket & Lens Assem. ....... 38-7912 S0.30
2 Antenna Transformer (Police). 32-2119 .65 50 Resistor (70000 ohms ½ watt ).. 33-370339 .20 Spring. ....... 28-8624 Per C .50
3 Antenna Transformer (S. W.) . 32-2109 .75 51 Resistor (70000 ohms ½ watt ). 33-370339 .20 Lens ................. 27-8310 .02
4 Comd{ensatingCondensers Ant 31-6092 .60 52 Condenser (.003 mfd. tubular) ... 30-4042 .20 Volume Control Shaft. ......... .... 28-6499 .10
5 Con enser (.05 mfd. tubu lar) .... 30-4020 .20 53 Output Transform er B, X, MX .. 32-7634 1.50 Volume Cont.rel Shaft Spring .. . ... 28-4117 Per C .40
6 Resistor (51000 ohms½ watt). 33-351339 .20 54 Resistor (190000 ohms½ watt ). 33-419339 .20 Retaining Clips . 28-8610 .03
7 Tuning Condenser ............. 31-1820 5.00 55 Resistor (51000 ohms½ watt). 33-351339 .20 Washer . .. ..... 28-4186 Per C .75
8 Compensating Condensers R. F. ... 31-6092 .60 56 Resistor (99000 ohms ½ watt) ... 33-399339 .20 Washer .............. 4436 Per C 1.50
9 R. F. Transfcrmer (Broadcast) .. 32-2105 .75 57 Resistor (490000 ohms ½ watt). 33-449339 .20 Socket. Power Tran s... .... .. .. .. . 27-6052
10 R. F. Transformer (Police). 32-2106 .65 58 Condenser (.1 mfd. tubular) ...... 30-4122 .20 Socket 8 prong . .... 27-6058 .II
11 Condense r ................. 59 Cone & Voice Coil K-34 Speaker .. 36-3174 .80 8ocket 7 prong . 27-6057 .II
12 Condense r (14 mmfd. mica). 30-1073 .20 Cone & Voice Coil H-25 Speaker. 02625 1.20 Tube Shield ...... 28-2726 .10
13 R. F. Transformer (S. W.) .... 32-2126 .55 60 Condenser (.003 mfd. tubular) . 30-4042 .20 Tube Shield Base. 28-3898 .03
14 Condenser (.05 mfd. tubu lar) . 30-a123 .20 61 Conde nser (.05 mfd. tubular) .. 30-4123 .20 I. F. Shield ......... 38-771)3 .20
15 Condense r (.05 mfd. tubular) ..... 30-4020 .20 62 Resistor (3500 ohms½ watt )... 33-235339 .20 Terminal Panel I. F. u~ it ..... 38-7703 .25
16 Electrolytic Condenser (16 mfd .) . .. 30-2118 1.65 63 Resistor (330000 chms ½ watt). 33-433339 .20 Sparer.................... ....... . .28-4001 Per C .25
17 Condense r (3500 mmfd. semi-fixed). . .. . .. 31-6097 .50 64 Conde nser (.05 mfd. tubular) .. 30-4454 .25 Gromm et Mtg. Tuning Condense r. 27-4325 .02
18 Resistor (10000 ohms ½ wat.t). 33-310339 .20 65 Resistor (13000 ohms 2 watt ). 33-313539 Grommet R. F. Unit ... ~7-4317 .04
19 Condense r (250 mmfd. mica). 30-1032 .25 66 Electrolytic Condense r ............. 30-2045 I.SO Sleeve Mtg. R. F. Unit . ... ........ 28-2257 .01
20 Condense r (. I mfd. tubular) ........... 30-4170 .25 67 Field Coil Assembly K-34 Speake r ... 36-3239 3.75 Spacer Mtg. R. F. Unit .. . ..... 27-7807 Per C .50
21 Compensato r (Ose. Series Broadcast ). 31-6056 .55 Field Ceil Assembly H-25 Speake r .. 36-3218 3.50 Screw Mtg. R. F. Unit. ... W-729 Per C .45
22 Osc. Transformer (Broadcast) ........ 32-2120 .65 68 Bias Resistor .... ......... ...... 33-3276 .20 Washer Mtg . R. F . Unit ................ 28-3927 .01
23 Compensati ng Condenseri;i Osc.. 31-6092 .60 69 Electrolytic Condenser (12 mfd.) ....... 30-2117 1.20 In sulat or Mt g. Electrolytic Condenser ... 27-7194 .01
24 Ose. Transformer (Police) ............ 32-2121 .40 70 Power Tran sformer 115 V., 50-60 cycles .. 32-7597 5.25 Bracket Mtg. Electrolytic Condenser ... 6440 .05
25 Condenser (1650 mmfd. semi-fixed) ... 31-6096 .40 Power Transfo rmer 115 V., 25-40 cycles. 32-7598 Nut Mtg. Volume & Tone Control. W-684 1.25
26 Osc. Tran sformer (8. W.) .......... 32-2110 .75 71 Condenser (.015-.015 mfcl. double). 3793-DG .40 Antenna Panel.. 38-7714 .15
27 Resistor (32000 chms ½ watt) .. 33-332339 .20 72 Pilot Lamp ................... 34-2039 .15 Speake r Cab le. 41-3201
28 Resistor (40000 ohms½ watt) . 33-340339 .20 73 Tone Control & A. C. Switch . 42-1182 .75 A. C. Cord .... J,-2183 .40
29 Resistor (15000 ohms I watt) .. 33-315439 .20 74 Ant. Switch ........ . 42-1170 1.10 Knob Tunin g.......... ... 27..4330 .10
30 Condenser (.25 mfd. tubular). 30-4446 .20 75 R. F. Range Switch . 42-1171 1.00 Knobs Tunin g Vernier .. 27-4331 .10
31 Shadow meter ........................ • 45-2189 2.50 76 Osc. Range Switch ..................... .42-1172 1.10 Knob Wave Switch . 27-4326 .10
32 Resistor , 700 ohms. Violet, Black , Brown . 33-1220 .20 Selector Switch Indexing Plate & Shaft .. 42-1173 .50 Knob Ton e & Volume . . . . . ... . 27-4332 .10
33 1st I. F. Tran sformer ................... 32-2100 1.50 Pilot Lamp Assembly .. 38-7706 .35 Shadow Mete r Mt g. Spring . .28-8623 Per C .70
34 2nd I. F. Transformer ......... 32-2102 1.50 Dial. ...... 27-5214 .40 Speake r K-34. B Cabinet .. 36-1229 7.25
35 Condenser (110 mmfd. mica) 30-1031 .20 Dial Hub .... 28-7187 .12 Speaker H-25. 3' -1236 8.25
36 Resistor (51000 ohms,½ watt) .... 33-351339 .20 Dial Clamp .. 28-2837 .10 Model B Cabinet
37 Condenser (110 mmfd. mica ) ... 30-1031 .20 Set Screw .. W-1641 .02 Bezel Frame & Plate Assembly. 40-5927 .30
38 Condenser (110 mmfd . mica) .... 30-1031 .20 Dial Guard. 27-8324 .02 Glass ........ 27-8298 .05
39 Resisto r (490000 ohms½ watt ) . . 33-449339 .20 Dial Gear ...... 28-7185 .10 Bezel Ring .. 28-3967 .35
40 Condenser (.008 mfd. tubular) ... 30-4112 .?O Thrust Spring... 28-8611 .01 Gasket . 27-8311 .01
41 Condenser (.01 mfd. tubular) ... 30-4124 .25 C Washer ...... .... 28-3904 .01
42 Volume Cont rol. .... .. ........ 33-5158 1.00 Thrust Wa.'!-her .... 28-3976 Per C .30 Model X & MXCabinet s
43 Condenser (.015 mfd. tubular) .. 30-4358 .20 Drive Gear ..... 31-1884 .25 Bott om Shield Plate ............. 28-3895
44 Condenser (.02 mfd. tubular) .. 30-4113 .20 Vernier Drive. 31-1871 .75 Bezel Frame & Plate Assembly. 40-5945 .70
45 Resistor (I megohm ½ watt) ... 33-510339 .20 Mask ................ 27-5198 .30 Gasket .... ... 27-8312 .01
46 Resistor (1 megohm ½ watt) .. 33-510339 .20 Mask Arm Assembly ............... 31-1866 .35 Screws.. .. .W-1644 Per C .50
47 Resistor (I megohm ½ watt). 33-510339 .20 Mask Guide Lamp Brack et Support .. .... 38-7844 .15 Glas• ... 27-8299 .06
48 Condenser (.1 mfd. tubular). 30-4122 .20 Mask Washer . . .27-8318 Per C .50 Ring .. 28-3987 .40
FiguresIn blacktype Indicate circled figures In Base View.
PHICES SUBJECT TO CHAKGE WITHOUT KOTICE
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Page4 PHILCO Parts and Service Division No. 253
2No.DET.
1ST.AUDIO
8Q7G
SLOWINGBEAM
INDICATOR fRONl or CHA:.51S
@DSC.I
18H.C.
~ 0SC.·1M.C.
(@R.f.
18M.C.
@ANT.I
18M.C.
FIii,. 5-Dlal Calibration FIii,. 6-Locatlon of I. F. Compensators FIii,. 7-Locatlons of R . F. Compensators
Alignment of Compensators
The accurate adjustment of the various compensating condensers iR vital to the
proper functioning of this receiver . There are four compensating condensers in
the I. F. Circuit, four in the Oscillator Circuit, three in the R . F. Amplifier Circuit
and three in the Antenna Circuit. Incorrect adjustment will cause loss of sensitivity,
unsatisfactory tone, and poor selectivity.
To accurate ly adjust this receiver, precision test equipment is necessary , A
signal generator such as the PHILCO MODEL 088 SIGNAL GENERA TOR ,
covering from 110 to 20,000 K. C. is recommended for adjusting the compensators
at the various frequencies specified. A visual indication of the receiver output
is also necessary to obtain correct adjustment of the compensators . PHILCO
MODEL 025 CIRCUIT TESTER contains a sensitive output meter and is recom-
mended for these ad ju stments.
Philco Fibre Handle Screw-driver No. 27-7059 completes the necessary equipment
for these adjustments. The locations of the various compensators are shown in
Figs. 6 and 7.
The following procedure must be observed in adjusting th e compensators:
DIAL CALIBRATION - In order to adjust this receiver correctly, the dial
must be aligned to track property with the tuning condenser. To do this, rotat e
the tuning condenser control to the extreme counter-clockwise position (maximum
capacity). Loosen the screw of dial hub, then turn dial until the glowing indicator
is centered on the first index line of dial scale (see Fig. 5). Now tighten the dial
hub set screw in this position.
SHADOW METER ADJUSTMENT-Remove aerial and allow tubes to warm
up . Then adjust shadow meter as follows:
1-Move the Shadow meter coil backwards and forwards, until the shadow is
within one-eighth of an inch of each side of the screen.
2-Remove the Rectifier tube from its socket, and rotate the shadow meter coil
for minimum shadow width .
3-Replace the Rectifier tube. The shadow should then return to maximum width
or within one-eighth of an inch of each side of the screen. If the shadow does
not return to maximum width, operations 1 and 2 should be continued until
it does .
OUTPUT METER -The 025 Output Meter is connected to the plate and
cathode terminals of one (6F6G) tube. Adjust the meter to use the (0-30) Volt
Scale.
During the I. F . and R. F. adjustments, the signal generator output sttould be
maintained at the lowest possible level that will give an indication on the output
meter. INTERMEDIATE FREQUENCY CIRCUIT
Frequency 470 K. C.
I-Connect the 088 Signal Generator output lead , through a .1 mfd. condenser,
to the control grid of the 6A8G tube; and th e ground connection of the output
lead to the chassis.
2-Set the range switch in position No. 1 (Broadcast), then rotate the tuning
condenser of the receiver to the maximum capacity position (counter-clockwise),
and adjust the signal generator for 470 K. C.
3-Adjust compensators Os 2nd I. F. Sec., @p 2nd I. F. Pri., ~s !st I. F. Sec., and
<i;J)p 1st ·r. F. Pri. for maximum reading on output meter.
RADIO FREQUENCY CIRCUIT
Tunlnl!, Ranl1,e-7.3 to 22.0 M. C.
1-Remove the signal generator output lead from the grid of 6A8G tube, and
connect it through the .1 mfd. condenser to terminal No. 1 on aerial input
panel, and the generator ground lead to terminal No . 3, rear of chassis.
(a) Termina ls 2 and 3 of aeria l input panel must be connected with connector
link provided on the panel, during these adjustments.
2-Se t the tuning range switch in position No. 3 (Short Wave) . Turn the signal
generator and receiver dials to 18 M. C. and adjust compensators @b Osc.,
(i)b R. F. and @b Ant. for maximum output (see note (a) below).
(a) The adjustment of the Radio Frequency compensator on the high frequency
range causes a slight detuning of the oscillator circuit. In order to overcome
this detuning effect , connect a variable condenser of approximately 350 mmfd .,
having a good vernier drive, across the oscillator section of the tuning condenser.
Leaving the signa l generator and receiver dials at 18 M. C., tune the added
condenser so that the second harmonic of the receiver oscillator will beat against
the signa l from the 088 signal gene rator bringing in the signal. The antenna
and R . F. compensato r @b and @b should then be adjusted to give maximum
output. Now remove the exte rn al condenser and turn compensator @b to
maximum capacity (clockwise) then without moving signal generator or receiver
tuning condenser, back off compensator @b (counter-clockwise) until a second
peak is reached on the output meter . The first peak is caused by tuning to
the image frequency signal and must not be used.
Tunlnl!, Ranl!,e-2.3 to 7.4 M. C.
I-Turn the range switch to position No . 2 (police). Rotate the signal generator
and receiver dials to 7.0 M. C. Then adjust compensator @a for maximum
output. Now turn the signal generator and receive r dials to 6.0 M. C. and
adjust compensators © a R . F. and © a Ant. for maximum reading on the
output meter.
Tunlnll. Ran 11,e-530 to 1720 K. C.
I-Set the range switch in position No. 1 (Broadcast). Set the 088 Signal Generator
indicator at 800 K. C. and the receiver dial at 1600 K. C.
(a) In adjusting the receive r at 1600 K. C. the second ha rm onic of 800 K. C.,
to which the signal genera tor is tuned, is used. The second harmoni c of 800
K . C. is 1600 K. C. Now adjust compensators @ Osc., @ R. F. and 0 Ant.
for maximum reading on output meter.
2-The low frequency end of the range is now tuned by turning the signal generator
and receiver dials to 600 K. C. and adjusting compensator ® Osc. series (see
Note (a) helow) for maximum reading on output meter.
(a) While compensator @ is being adjusted, the tuning condenser must be
rolled for maximum output. This is accomplished as follows: First tune com-
pensator (!!}for maximum output. Then vary the tuning conde nser for maximum
output at 600 K. C. Now retune compensator ® and again va ry the tuning
condenser back and forth at 600 K. C. for maximum output. This operation
of first turning the compensator then the tuning condenser is continued until
maximum output is obtained at the 600 K. C. frequency.
3-After the low frequency (600 K. C.) end of the range is adjusted, the 1600
K. C. end is readjusted , as given in Paragr aph (1) above, to correct any variation
that the low. frequency series com pensa tor ma y have ca used in the alignment
of the high frequency end .
4-Now turn the signal generator and receiver dials to 1500 K. C. and read just
compensato rs © Ant., and ® R. F., for maximum output.
NEW PROFITABLEBUSINESS
PHILCO
Noise-Elimination
Kit __,,,...,
for ALL SERVICEMEN
■ ■ ■ ■
Part No. 45-
ListPrice S15.oo
June, 1936 Printed in U. S. A.
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