Philips 470 a service manual 2

Page 1

'TR

VI lSlzpp/L'mem)

ADER SERVICE SHEET

358

covered by the Philips 47oA

541nm! [plus rectifier) AC 3-banrl

silperhct. which is suitable [or mains oi

loo/:00 Y, 5o-iooL1/b. PIOVISIOW is

made {or both a graninphone piikvup
ltllli zlli extension speaker.

CIRCUIT DESCRIPTION

Aerial input on MW and l, \in
coupling coils L2, L3 to capacity coupled
bandpass filter. Primary coils L4, L5
.lro tuned by 027; secondaries L8. L9
by 029; ioupling by 03, C4. ()n SW,
input is \'l'd coupling «toil L6 to >lngle
timed CllLllil L7, 029. L1, 025 ('OllniCI'CYl

SH()RT-\\,\\li range of 16-751 in
A i

THE WIRELESS & ELECTRICAL TRADER

.. PHILIPS 470A

October 8, 1938

3-BAND AC SUPERHET

across aerial circuit, liltels out signal:
at intermediate irequoncy.

First Valve (V1, Mullard metaJJised F04)
is an octode operating as frequency
changer with electron couplillgl Oscillator
grid coils L10 (SW), L11 NW) and L12
lLV) itre tuned by C30 ; Parallel trimming
by 031 (ll/[\Vl Lind 032 (L\\') , series
tntclting by 010 (MW) and as (L\\')
Reaction by coils L13 is), L14 {MW}
.md L15 (LVV),

Second vach (V2, Mallard metallised
Wm) is it Vitrinblermu RF pentode
operating as intermediate frequency
amplifier with tuned-primary tuned
secondary transformer couplings C33,
L16. L17, 034 and C35. L18, L19, 036.

Intermediate irequency 128 KG/S.

Diode second detector is part of double
diode pentode output valve (V3, Mullsrd
Pen4DD). Audio frequency component
in rectified output is developed across
loud resistances R10, R11, the hitter being
the manual Volume control, and passed
\in All coupling condenser 019, 1F filter
.020. 3.15 and CG reSistance RIB to CC
oi pentode section which provides the
Al? amplification. Provision for connection
of gramophone pick-up between junction
of Rm, 311, and chassis. Variable tone
control in anode circuit by 3.13, 021. 314,
line 022 provides fixed tone correction.

Provision for Connection of Ion impedance
external speaker across secondary oi T1.

Second diode of V3, ted (tom V2
anode Via 014, provides DC potential
which is developed across load resistance
320 and led back through decoupling
circuits as GB to FC (except on SW) and
ii" valves, giving automatic volume
control, Delay voltage is obtained from
drop along R17, R18 in Cathode leitd to
chassis.

HT current is supplied by lull-mire
rectifying \alve (V4, Philips 182D.
Smoothing by electrolytic condensers

018, 023 and feed resistance 312.
DISMANTLING THE SET

The chassis Ltnd speaker can be remoted
from the cabinet :is it complete assembly.

Removing Assemblyvlt it is desired
to remove the chassis from the cabinet it
is best to withdraw the chassis and speaker
together, when the Chasilh ~2tn be tested
under operating conditions. To do this.
remove the two knobs at the front of the
cabinet (recessed grub screws) and the
two knobs at the sides of the cabinet
(grub screws accessible from the inside of
the cabinet.)

Unsolder the earthing lend to the screen
on the bottom of the cabinet and remove
the six screws holding the speaker subr

Cl?
u
1-

RH

C20

Circuit diagram oflhe Philips 470A 3-band AC tuperhet. 024 may be omitted in some chassis,
while a decoupling resistance and conder ser may be included in the anode circuit of V1.

SIS

Page 2

October 8, 1938

Under-chassis
view. Diagrams
of the rwu wave-

l change switch
i units are over-
leaf C32 is of

the wire-wound
adjustable type.
L1, belonging to
the aerial IF
filter, is the only
mil beneath the
chassis.

THE WIRELESS & ELECTRICAL

hullll: to the front of the cabinet, when L ie

msemhly can be Withdrawn
Wily; rzplucm

, do not for

gel t0 Nave

the metal plates on the top middle al ri

hottoiii rightrhanll

fixing
. note that the knobs

5Cr.~\\>
With white circles

him]

go on the spindles at the front.
Removing speaker.~1he spetkei' uln
be removed from the cabinet by UnSOldk' -

mg the leads, slackening the
holdingy it to

nuts gm rl washers}

three clam} '
the subrbaffle

(m ts, lock

and swivellllig tllt'l 1

out of the way, "View replacing, see that

the terminal panel
(OHHCCL the leads

is on the
as follows, numbering

left «And

Ill-0 tags from bottom to top:~l and .5

Joinitl together, leurl
output transformer
scale assembly; 3.
no output transformer.

ttfiNDL Slilxi

lilingr 9000.000

:00 .. .
-\url.ll rm. sw 1000...».
w 1100.00.00 .

~, 0d v.10.

u. .-0...le...~. r

W cm-uu l W in} v.-

llt. .zrcun MW tinrkc

\l ..~v:.
rwllpllllg

\ _v (let-00010...

\ a h!) tierollpllng ..

k5 lplmg in \'3 l\\'( diode

0.0.000 1.00.0 .

l upm

\' , muhml.» M500»

l'.ul HT smrmthlntv 5.

A .~0:.pl...g .0 i. . 0.0.x.-
. ms:

worm-.0. ..
0000mm .
RF by runs .
him 100...:

. luv-.1 :0.
l: t T

.-002\.>0;

nu... 0. 1.... 1.000: .

Hind puss 50.; tuning
, m lliltorclrrllittllullig
(is ,ull MW ililnmcr
, w... my 0.0.0.0.-
.0. ll 0005, 00, 0.00.:
.0. W 0.0.5, 500 0.00.:
:nd [F (runs. pn. tuning
20.1 H: «0.0:, 500. tuning

4.09"..4 9
,5

liT/MJM"

MW and LW aerial 00001005.
5.0.0500. mummg 000.10..-

0..0.l0 1.04 5(. 0'0.

IrlillliP [0th Control

l 0mm: 0... MW {0.00.00}

13.001015: «e1 .\lw 000.00. I

to top stud on
and oarthing load in
lead to bottmn arm

COMPONENTS AND VALUES
\

90009.
WUUOOX

. 4 oxfi
95
. 95
9099...
5099,-
0090, l

l
l

u l
0 05
0 05
0 00000.
n 15
n 70....K
:5 )
12-

l

0-. .0:
31"
0-. z
.1 . 00.
0 . 000;
0 000 0,
01.300;
0... m m
0-0000.
000003
0 0 mo 1
-0 .0.
0.0 t...

. 1 00m

0-0. 0.
i Flu r. t

l Val'les

[HZSIS] Axclr 5 (0mm;

lil \l. [mum to 000000100: .0000.»
R2 v. u; stabiliwr . 50
R3 l V. fixed GB mama... » 050
k. \'. cu mistam.» 50,000
kg, l 0.x 00000.. 00.00.00 . 10,000
l<0 . and LW damping ,, 500
K7 . (isand VI 0... 01¢ 1 0,000
Rt H1 .000 mutanccs (l .2500
l<., v; hxrrl (.ll rmsmuct :50
Rio Pm v; gnu 0.0.ie 10ml . moon '
Ru in... V; signal diode l0,..l
.00....01volumecunu-ol , l 300.000
R12 HT .000, except. .0 v.1 000.10,, 2.000
Ki . ramble tone .10....01 . . 50,000
in; Part 0......1010 {our 000001 .. . .00
R15 v grid 3.0000. ,. .. .0,000
km in; lEMSIRHCC . .. 1,000,000
H17 (.13 ;....l AVG (1.1., .01 5. .00
R18 .010 .mlstmces 4 mo
km AVCllnevietollpllng ,. 3.000.000

7 v. A n, rlflle 109.0 0.0.000

tlllllzR (UMIWVENIS

5.; 7.70170: 00..

, l.. .
1' ~' 0.01 MW and lw 00.01.00 4"
9x _ .1 .
I , LU]: . , . .
I; l 5 500.150.. pumary r... t
l 0 Aerial sw 00001.00 00.. ,
l 7 dorm] sw 20.00.; 00.1. i, .
l i ; . Bnndqmn secondar) rink l .1:
. l..0 \k Circuit. Vl....0.g ~ .l l 0-.
l... 05.; .00.. MW 00...... 00.1 ..-0
Ln ()St 01mm LW «0.00.; toil . ;_. 0
Lu l mullaiorswmartiunmil .1 l i 4
1, (00.11.00. Mvt'rcartloul'oll ,, 7)
I45 Usrdlanu l.W macnm. . oi]
l .n .

, lsl IF trans.

l :h . . 5 _ ,1 ln' _
L) l 200 ii. 1.00, 5 _.8 .30-0
l.:n Speaks. spnechcull .. 4 0
T. 1 00:00: .00..» {£3 23
,1»... 10...] -0
['1 . Man:V Caitr «8. 0'!

mm

VALVE ANALYSIS

\CthL. voltages and currents given in

the table (col 3) are those measured in
our receiver when it was operating on
mains of 227 V, using the 220 V tapping
on the mains transformer The receiver
we tune-d to the lowest wavelength on

TRADER

VII v

(Supplement)

the medium bnnil and the volume tontinl
was at maximum, but there was no signal
input.

Voltages were measured on the
scale of
chassis

.100 \i
a model 7 Universal Avomete
being negative.

\ \
( 400d. l Anodi- . 50.00..

iten
Valve Voltugn l Luneni Voltage Imrreut .
(V) l (0m) m 004,
l I an ,
\l. H, 5 00 .l lalot .00 l l 0
:15 l
\ \l'pll :35 77 .m _, 7
glmlflfl) l :04 . -0 1 s < x
V: m. ~7~+ 7

1 hash ..0000, AL,

GENERAL NOTES

Switches.¥SI-Sl4 are the
switches, ganged in
beneath the chassis

wa veba nd
two rotary units
These are indicated

'. and shoun in

View.

The table (page VIII) gives the switrh
positions for the three control settings
starting from fully anti-clockwise. \
dash indicates open. and 0, closed.

815, 816 are the 93113 mains switches.
ganged with the volume control R11-
and as indicated in the uuderichassis
View, they are at the front of the volume
control.

Coils,~L1 is beneath the Chassis, and H
unscreened. 1.2-1.5; LB-LB; L10-L15;
and the ll transformers L16, L17 and
L18, 1.19 are in t ,e screened units on the
rhassis deck. Each unit contains one
trimmer, additional trimmers, in the
case of the IF units, being,7 mounted
nearby, on the chassis (luck.

Scale Lamp: This is at Philips MES
type, with a frosted bulb its part number
.< 8042-07.

External Speaker. Two sockets
provided at the rear of the chassis for a
low impedance (570) external speaker.

Condenser 032 -1lu's is a ere-Wollnd
adjustable type.

annulled owlmf