Philips 470 u service manual 2

Page 1

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TRADER " SERVICE SHEET

621

I lllilflhl WnVPllillNis arc proiidcd iii
the Philips 470U, the SW i-gr
Iwiiir 16.775l In. Thc ietcnri i,-
ii 5 mlvo (p us rcttilicr) superhct, (esigiicc
to operate limit A( or llt mains of 200
Hot] \n SilleU (' S III IIlt ruse (ii [\(i. N(
xnltngt- iliIJllSllllilli is provided. zi Ilnri'tit
Itl lump regulating: the heater circuit
Illlltlll WIIIIH] the mains voltagi- mum
quoted
M) pmwsinn is made for the Colncciltm
ot d gruinoplionc pickup or an «ixtrirnnl
>yrlilhel'. but an indicator is fiitcd to
- iIu- wxvrlmnd to which the "CPCiVCI
is Ili IitiI.
Pelmxr «late (Ill/l m'i'qi'nul Ili'illI .
Ivy/mt. 1958: £8 18:. 6d.
CIRCUIT DESCRIPTION

Aerial Input on ,\I\V and LW via 01
and coupling coils L2, L3 to (opacity

Supplement to The IVireIexr {'9
film! 552.er 12:. L943

PHILIPS 47

AC/DC SUPERHET

touplcrl band pass filter. Primary coils
LO (MW) and L5 (L\\') are tuned by
019: secondary coils L10 iMWt and L11
(LV) by 031. Coupling by 05, OE, With
the additional inductive Coupling by L6,
L1 on MW only.

On SW. input is via C1 anti couplingr
mil L8 to single luncd t'ii'ouil L9, 631.

Image suppression by 03. Mi" tap"
tinupling iiy C4. Aerial circuit.IF filtcrr
nu; by L1, 017. The :ielial and earth
sockets are isolated from the, chassis (and
mains) by condensers G1, 01, and in order
to prevent these condensers from develop-
ing a charge. H1 is connected between
them to maintain DC continuity.

First valve (V1, Mullard metallised
EKZ) is an ocinde operating as frequency
changer with election coupling Oscilla-
tnrgrid (tolls L11 rswl, Lia (MW) and
L14 (LW) are timed by on. Parallel
trimming by 033 (M\\') and can (LVV);
wries tracking by G11 HIVV) and 010
(IAV). Control grill condenser 69 prcr
vents L12 from shortecircuiting the (G
resistance RS on SW, but on MV and TAV
CD is shortrciicuited by SS, the tracking
condensers 010, C11 providing: DC isola-
Lion.

Reaction coupling: from anode by coils
L15 (SWL L15 tMVI and L11 (JAY). and
damping is provided by resistances R7
[S\V) and R8 (MW and IAV).

Second valve (V2, Mullurd metallised
EFO) is n variablerinu RF pentode Opel

citing as intermediate frequency amplifier
with tunedprimary, tunedsocondurv
transformer couplings (235, L18, L111, 038
and 0:11, L20, L21, 038.

Intermediate lrequency 128 Kc/S.

Diode second detector is part of tloublc
diode output pentode valve (V3, Mulllrd
GBL1). Audio frequency component in
rectified output is developed across
manual volume R, which also operates
its load resistance, and passed via AF
coupling condenser 020 and grid stopper
R16 to CG oi pentode section. IF filter
ing by 011, R13 and the screening of the
leads to R111 in diode circuit, and 021, R16
and the grid/cathode capacity in control
grid circuit. No provision is made ior
the connection of a gramophone pickup.

Second diode of V3, fed from V1 anode
Via 019, provides DC potential which is
developed across load resistance R22 and
ied back through decoupling circuits as
GB to FC (cxccpt on SW band) and IF
valves, giving automatic volume control.

Delay voltage, together with GB for
pentode section, is obtained from the drop
along: resistances R19, R20, which form
a potential divider in the cathode load to
chassis.

Fixed tone correction by 623 in anode
r . it, Variable tone control by variable
resistance R17 and 022, R18, also in
anode circuit. No provision is made for
the connection of {in external speaker.

It? RIO RII

Cl
' an
L8 2
III
C29
=C§
Q =cs
--i

"4

rom chassis by condensers Cl, C2.

.q

Circuit diagram of the Philips 470U 3-band ACDC superhet. RI provides DC continuity between the A and E sockets, which are isolai
The speech coil circuit, metal parts of the speaker frame, scale. lamp assembly and com
mountinghrackets an connezicd directly [0 the E socket, while the core of the output transformer T1 and its electrostatic screen :

connected to chassis.

Page 2

Supplement ta The Wireleri {y
Electrical Trader, May 22, 1943

Plan view of the chassis.
hafiie in a single unit.

The chassis and speaker complete are mounted on the
The trimmers, all of which with the exception of C34 are

indicated here, should be sealed with a touch of hot wax after adjustment R3 is
located in VI top cap.

The core of the output transformer T1
is connected directly to chassis, but the
metal speaker frame, T1 secondary and
speech coil L12, together with the scale
assembly and casings and brackets of the
volume and tone Controls arc connected
directly to the earth socket so that they
are isolated imm the chassis by Ca.

When the receiver is operatin from Al?
mains, lIT current is supplier? hy lHtl
half-wave rectifying Valve (Vl,'MIrllard
0Y1), which, With Iltl 11mins, behaves as
a. low resistance. Smoothing is effected
by irnn-mierl choke L28 and large capar
city electrolytic Condensers 014, 025.

Valve heaters, together with scale lamp
and current re ulating ballast resistance
(BIrwtter P Ill G1), are Connected in
series across mains input Filter circuit
comprising air cored chokes L211, L25 and
bypass condenser (:26 suppresses mains

borne interference

Current limiting rc-

sistancc R23 protects VB from damage
due to initial current surges, while {uses
F1, F1 protect tlir mains input Lireuit
from accidental ahertcircuits.

VALVE ANALYSIS

Valve voltages 11nd currents given in

the table below . taken from those
0 Anulle Ant-tie . hereon Screen
Vahe Vultagc iiirrent Voltage Current
A l (v) (um i (V) (mA)

1 ii

{17 rm

1th 7-5 10% 2-0

105 380 l 1240 7-0

. 215* , ' 7

7 7 r (miiridFiLieimssis, 1w.

quoted in the makers manual. They

represent conditions to he, expected in an

C24

r

I are isolated
and control
lc screen are

some UMP

\

Pr LIL»?
LN} WW

PHILIPS
470U

621

average chassis'when it is operating with
no signal input, and were obtained by
taking the aveiztge readings of measure-
ments maria on it large number oi re-
ceivers. Differences up tn. say, 20 per
cert. should not ner'tsszirilt is. taken as
inilirating a fault.

Voltages were measured n11 lhilips test
hon is type 4256 and type 7629, whose
meters have n resistaiire ni' 2,000 (l per
volt. the negative lead being connected
in earl-1 muse to the. cathode of the valve
cm (erllf(l. not. to chassis. This rlnes not.
of course. apply to VI. The total cow
suinptmn 75 the receiver on 225 V mains
is 66 watts.

COMPONENTS AND VALUES

RESISTANCE-5 Values
(ohms)
R i 1 Aerial circuit shunt . 100000
R! , V1 hex. CG decoupling. l 100,000
Bi V 1 lit-ex grid ummm . 710
R t V 1 fixed (VB resistance 400
11 1 \ l 050. grid stopper 10
R i V 1 one. CG resistante l 50.000
R l l SW reactiun damning 20.000
R 1 l MW and LW reaction
dumping 4,000
R l V 1 one. anode HT feed 10.000
R [0 V 1 50 ET feed 125,000
Bil V2 58 ET feed . .000
R {2 V2 fixed GB resistance .. 320
me i r shopper 50,000
R [4 Manual volume Control
. va signal diode load. 500.000
Rlfi V 8 pent. CG rmismnce 1.000.000
R M V 3 pent. grid stopper 10,000
X L7 V ariable tone control 50,000
R is Part variable tone control 100
R L9 V3 pcntodv GB And AVG 200
11"!) delay resistances 400
i 1 AVG line decoupling 2,000,000
R32 V3 AVC diode load 600,000' 1
5}: V4 surge limiter 125

- Made up or two 800 o assume; immccird
in rarallel.

('ONDFINSERS Values
(HF)
tl Aerial and earth isnlatiml 0- 001
(2 condensers
. (3 Image suppressor 0- 00004
{74 i [up " aerial Coupling 0-000016
05 Band- 138.35 coupling con- 0-0125
ca denser! 0-04 .
37 A trial cite. SW trimmer 00000126
Us \ i cathode by- ass 0'05
(0 \i 050. CG ( W) con-
denser . . i 0 00005
01 0~0. cilc. LW trucker 0 00068
Cl . Uic. Circi MW tracker 0 001576
Cll VI me. anode decoupling 0 05
('l.'. v: St; decnupling . '
Cl 1 1 v: ('G decuupllng
(10 \ 1! SU decoupling
(1M \' ' cathode hy- pass
(1 ll bV-pass
cw \ :miioue hy- ss
(,l'l (iruplinn to .l AVi
:limle 0000009
02 A" Coupling In V"i [if-Ii»
(Ode .. 0-0025
ll lIV-Dtltfl 0'00008
rm mum-tn 0 i
Fixed tone 00mi- , 1r 0-002 l
} H l smtimliing min» .
K . ,rs
Vi|i 3 1w h\- -p 002
Atrial IF filter tiilllug 0 UUUI
B P pri. MW trimmer 0-00003
I} indrpass pri. tuning 000040
B P we. MVV'trimmFr 0110003
Bind-pass sec. and aerial
SW tuning .. 04100-19
Oscillator circuitt unimz l 000040
04. Cin. MVV trimmer . 0000]
Use. eirc. LW trimmer 0100003
Ist [F trans, pri. tuning 0-000]
lst ITi trims. sec. tuning 00001
ZliletlHiN pn. tuning 0-0001 l
2nd 1F trans sec. tuning 11-0001
Electrulytic. 1 Variable. 3 Pry-set.