Philips 855 x service manual

Page 1

PHILIPS 855x

Firerralrr, pllti rcttifirr, tltr
umrttbatltl ltiblttmatlcl 5U!!(I']I(l itll/l

tncchaiiiml push - bullmt tutti/it].
)

Lmlrlml, 30,1

'rcult.7Thc tuning:
receiver tire unusual in it way that is
immediately apparent from
The input circuit on
medium and long waves is n hand-pass
the \'l gl'ltl cmls being

circuit diagram.

Radio h'larketini; Service Engineer

November, 1940

thi, 1.17, tuned by a cundemer shown
between V1 and Y2. The coupling
between V1 ilnd V2 is then aperiodic,
tllu signals being developed across R4 and
applied to \'2 grid through C20.

0n the short Waves. the aerial is connected to
\l through tronsiorincr coils. A similnr
nrrangcincnt with the gang section transferred
to the grid cirruii forms the coupling between
\ 2 and

u is n rndlu- -froquciic\' runpliiicr and \
thc frequenc Clldlluor. llnth \dll'
A. v r. ltiils Mil rcslstoncr with I).
condensers heiorc the _. ids. The oscillator
section of V2 has the tunml coils rod li_\
and condenser from the nuode with sepuruto
coupled uiudin i the grid circuit.

The llrst Ll. irilllJorllIer has n switched
extra winding n the sccondorr ior incrcnscd
Imnd-widtli. \ i the Ll" npliiicr. hoth
lit transformers are pcriuenlnht - trinnned.

Roth dcnmdulstion nnd AX (limit-ts are
housed with the output penlode in \'
dcmodnlntion nc vork i
iorward and includes 5
radio and tonnoct .- The \olume
control rccds the peutode section or i J a coni-
hined 1. l- mnpllircr and tlnlilt" indicator.

The bottom end or the volume control and
a toppling on it are connected through it resistr
mice-condenser network to n thi l w' ding on
the output. transformer for negative reed-hack,
'lllis winding is t'clitre»iappetl, and the other
hnlrls connected hook to R275, n hit-h is at variable

L3560

tone control, and to L37, (65. which (orrn a
whistle iiiter.

The anode circuit or the V4 pentode section
pmv' cs HT, for Iht: indicator section and
srnphhcd n1", for the grid of v.3. The A.\',(.
diode of this valve receives a delay bias from a
voltage divider cons nu or Rio, nil, ital.
R43, Negative A.V. voltnnes devclcpctlrtcross
lml. R43, are red hack to \l. v2 nnd v3.

The {nil-wore rectiller, \o, provides tixr
without it choke for smoothing R1 mitl (_
provide is smoothed supply for \l \i, and a
resistor, mot in the nnun ncrni e hnc provides
o \oltnse drop used to hizl \5,

PILOT Linc: Philips m1. yrle. Xo. 8,00).
lrtnision is made for a pielcup and a 5-7 ohn.
extension ~ er,

so Tt:n , The switch sections of the
circuit dial. nm represent the act unl construction,
The two concentric rings of dots ond small
circles rrprescnt the stator (tired piiri) or ouch
s itchunit. Thclineslietweenthcsccoricculrio
rings, whether short rudiol lines or arts (whirh
may be in dot lines), represent "to olcinr-nts on
tho rotor which pctform the various courioctions
between the stator contar .

As drawn. the switthc l 4, are in the s. \i

- M and Lw. post ions follow in the

-i by then ws lhe sel ll\l

is narron and tho l.l'. sit-rich,

GANGING

1,1". L'llilXTlTS.*S(l in lxlt nI_, nilllnlt- mix.

tone treble and selecthity IHII'YUWr llljtl
473 k0. to V2 gritlr

T5 TI T7

7500 o
ofi @@

656
i2. .oia..is@@ @ @@ E

R
go

MI

V6

This receiver has an RF.
stage before the frequency-
changer and the electronic
tuning indicator incorpor-
ates an L.F. amplifier.
The circuit follows the usual
Philips lines, and is not
ailected by the mechanical
auto-tuning system. The
switch diagrams are
explained in the text.

(Itllllml NI) lilillfil, aiinxs L.
W {or minimum.
ross I. i and tut
nnd . i
r-nnmrnptnir . eeni coil cor s.
\i.\\ iiANil. -Atljllsl unity with Philips
n-innnins onugc (or tlidl to [88 m). iuiect
l . l0 lrt-s. tutti ttdiust T1 1nd T3
inject .unl tnnc to sit: k and pail with T4.
itcpenc l .35") kc inliustincnt
I. llA\l) ~Il\]c(i 100 km; (line it) 750 m.
nndsdi st T.. Injectainltuucinion kcs. and
pnd \ in To Repeat 400 kcs. ndiustmcn't,
Philips rccommend rhc followinr method or
pitillllnu : After trimming rtt the low wavelength
curl orthc hand, connect the anode of V2 through
n small capacity to the aerial of on ndrlitionsl
n river. Transfer output meter to this set.
Slinrtrn ouit the oscillator. Tune both receivers
. nmn on pudding frequency.
Dial x ' tirst to lett, then to right, finding
two pom s at which output drops to n third.
set tliztl midway between these points, remove.
extrn set, rind adiust padding condenser for
untxnnui

. li.ND.-1njccit and tune to 20.3 mr.
TT (nrst posit from minimum capacity)

'28. and atljnst
('onlwit the so nuntrls.
holy adjust L2.

[Mat and tune, to ti mo, adjust loop K (see
circuit) for maximum, Repeat trimming at
2043 me,

PUSH KEYS

rush down key, insert special tool (kept in
ltrtck oi rohinct) into aperture below keyboard,
mid Hittite adjusting silteW until required
station is tuned in accurately by dial and tuninil
inglimtfiri

go the \mvebilnd of one or three leftr
, insert tool (without depressing key)
and turn anti-clockwise a row turns for MAW,
or turn clockwise until tight for L.w.

VALVE READINGS

I . Ti/pr. hlerhodfi. Tolls. M11.
Anode 170
Screen 210 .
(athotle 4 6.

2 . . EtHI} Anode 2141 5.
Screen 115 .7
USC. annde 70 5.5
Fathode 2.3 11.5

I} . . EFS) Anode 210 4.8
Screen 90 1.4
ifathode 2 [3,2

4 . . EFML Anode 100 .52
Screen 22 7
Indicator 150 .34
Cathode 1.2 .86

.3 . . HRTJ Anode 215 91
Screen 210
fathode

(i . . . 7.1 rnihotle 251i

Continued on appusitc page

Page 2

November, 1940

Radio Marketing Service Engineer

vi

PHILIPS 7882C

D.C.-A.C. VIBRATOR
CONVERTER

Vibrator cmttertei unit for
operating All mains receivers/ram
110-145 or 2tJ0~245 «:01! I).(.
supplies. Made by Philips Lamps,
Ltd, Century House, Shaftesbury
Avenue, London, 20.2.

c Huh-The circuit is easier to follow

if it is remembered that it falls into
two sections. One path is solely DO.
and drives the vibrator. The other path is
0.0. up to the vibrator, which acts as a
cross-over switch, and from there
on is A.C.

The principal items in the circuit are: the
Vibrator with cnerglsing coil L3, springs X and v,
and contacts a, B, c, D, E; an overload pro-
tection relay comprising Ll, L2, and circuit
breaker, RY, shunted by 01; and a mains
Voltage adjustment consisting or $2 and 53,
which are operated together. ihe other coin-
ponenta are mostly tutors to prevent )ioi
being fed into either the no. input or the .
output.

Current driving
the vibrator
flows in the
upper section of
the diagram only.
D.C. also flows
to the two vi-
brator springs.
These act as a
cross - over
switch, the
current alterna-
ting through the
lower arm of
the diagram.

OOOOOOOOOA or n .I

h

)CdVlAIIEd 'SNVEL SNIVW

own lllc circuit la km for operation at
lltlr . Volts. III this position (Ii? Ilrst of the
paths mentioned nhou, that is, the current
driiinc the vibrator, flows throng si (nun 5
switch), fuse. Ll, L2, 1i2, L3. contact A, spring

tLrili, L12, its and iii in parallel, mains
c .

X.

When the current passes through 1.3. thc spring

attracted to the inaimetiseil core (r aim
nun ~ b-ina coupled to .\). The morcrncnt or
x hre. the contact. A, the tuner causes, the
core of 1.3 deinoguetises and x sprliltzs back.
The contact A is remade and the uholc process
is rcpeuted rolltilnlously.

The second or combined 1).(' i
now hetollowcd. With the sprinir. lithe plan-on
shown, the current flows through s1, Li, .2,
relay switch, Lip, r, 1, L4, 1.5, Lo. PM in:
through the mains ii-u former military it
returns rin, fuse, L7, L , Li), ii, x, Ll], Liz,
R3 and 1Hill])1ilt|ll91,lllall|s cu-itch.

A: this pulse or current ilorrc, the springs are
attracted tuunrdx L3 core, This hmilha con-

RS

C6

C2

12

lb

Details of the condenser block in
the Philips converter.

UM: (. Ii. :lilll liliilus L'fiIIIlH"~ D, I). The
iulreiit lhtn flows through SI, fuse, J.l, L2,
RY mid Irll) as before, and the thmllilh Y,
1), 1.0, L8. L7, fuse, transformer. L6, L5, 1A, B,
X, L11, 1.12, mill R4, mains switch,

\Yith each swing of the springs, therefore.
the Current Changes its direction through the
truirsrorinor prinnrry.

'heli operflflm, from 2007.45 Volt mains
S. S3 re s\ [riled over. This reducer; the rel
r d by shot rig out l 2, and increases the circuit
resistance in ilepriu it its ofils shunt, iii. and
by putting itl in series \\ iih it

The filter (5, (17, 1.1 l. _ , ,
Lin, Lil. (lth ('1: and i ; m-u . lilIFIffTKIH't
from the Vibrator from entering the mains.

The filter ('8, (5, L4, LEI, (ill), ('11, 1.5, LS,
C12, ('13. LG, I.T préunth interfnrelicc from [he
vilrrulor from cuterilm the receive .

The relay Ll, L2, Kr tcinpornriiy break,- the
Current on siiillll (nerlnails inn]. prevents the
{use blowing unnecessarily.

PRACTICAL

The chuuae-ovor from Ar. to l).('. operation
i.- clrectcd simply by rotating the safety contact
on the bar-kplate half a turn, The safety
contact, not involving circuit features, is not
shown in our theoretical diagram,

The Vibrator unit. 7931, cannot he repaired.
and if ilefeithe must be replaced, It is impor-
tlmt thot all leads should be returned to their
original positions ait er any repaira.

The vibrator is replaced by dcinountinr the
two boxes. To replace other comllunents H

l. Slacken oiithe screw in outer box.

2. Take off nuts on voltage switch plate.

31. \Yithdrilw inner box from outer box.
(Remember the lead.)

To i'hnngc the filter Foils, runtleiiser box or
ll 1 , ICE, heat the three snldvrell joints and remove
the LUIHlEIISPI hox from the srreiii box. Do not
heiul condenser Iiox seams,

The order otthc filter colic ix: 112, hi, L11,

Lit). lm, 1.5. I . Lil. l. Mini 1.? are blind

round LC: :qu ('l .
INTERFEBENGE
if interference i rperionhcil, tin» leads to the

nnmles of the rcicn'er rectifier valve should. be
sureeliml and one or two ripple condensers titted.

FIESISTANCES

(films. L

I

..)

I
I
I
I

When Tone Changes

WHEN a set comes ill for overhaul

because of defective tonal response
what are the most probable causes?
Such a defect usually takes the form of
too little or too much bass.

First points to check are the speaker
cone eentring, and, if power is also
lacking, the resistance of the speaker-
trausformer windings.

An open circuit bias decoupling eon»
denser causes an overall loss of amplifica-
tion. If the capacity is merely reduced,
however, this will discriminate against
the lower frequencie .

An open L.li. coupling condenser will
cause a big loss in amplification and
complete loss of the lower frequencies.

An open anode decoupling condenser
can also modify tone by introducing
feed-back. It may increase or decrease
bass according to the feedback phase.

The shape of the tuning circuits also
affects tonal response. Very selective
tuning reduces the high notes. If a set
is too boomy it is Worth while to try
staggering the LR circuits to flatten
the peak.

Where tone control circuits are fitted,
faults in these or the associated switching
should be looked foniC. S. R.

PHILIPS 355x

Continued from page viii

WINDINGS
L. 01m.

Uhnu.

CONDENSERS
0. 31/4113, f.
i 38 103 llullfils.
39 ii: ,,
4] .047
41 18 uunfdu.
42 39 ,,
. 43 .050
.039 4! .033
100 miufils. 45 .13
.047 Ali 150 mmfde.
.im 7 2,200,,
3.9 mmfds. My .058
180 ,, .22
.047 .0022
.047 .056
17 mmlds. .18
470 ,, .18
4,200 ,, 1,500 mmfdt'.
330 ,, 180 .,
33 ,, . . 130 ,,
9-1 ,, ,, .033
iii" ,, . .068
. .047 .15
4 .065 . . .027
. . 390 mmfils,
RESISTANCES
R Ohms, I
l . . 1,200
2 . . .252 meg.
. . ($80
4 i . 6,800
r . . .82 me
(i . . 470
i , . 22,000
5 . . 47,000
9 . .