Philips 131 u service manual

Page 1

(All rights renewed, This service (on. o u u no copy-

right of Wmawss at IIHII'TILICAL Tluo.

and may not

be reproduced, in wllnlc or in part. wilmut [minlissimhl

TRADER SERVICE SHEET

Appearance of the I3IU Starlet."

LOW-IMPEDANCE frame aerial
A is a feature of the Philips 151U
Starlet," a 4-valve plu. rectifier
ZAband :\.C./D.C. uperhct lor mains )I
110 250 V, 50100c in the can of AA,
Wavcband ranges are 1856801 and 1,1537
2,000m. 'l'be I'raine aerial cumists of a
solid aluminium strip.
Model 210U is on earlier 3-band version

oi the 1311' with :i SW. band coverage
of 16r550.5n1. The diflercnccs between
the two models are fully covered in the
circuit diagram below.

Release dates and original {Ir-ices:
Model IjIU, june 1955, ,{ii 185 5d;
Model 210E, August 1952, {:5 ms 511.
Purchase tax extra.

CIRCUIT DESCRIPTION

Apoliodic lramo neiial input from L1
via. L5 and L6 to single-tuned circuits
La, c21 (uni) and L1, (:21 (L.W.). A
S.\\. band Is provided in Model 21m,
and has an internal plate aerial whirl:
is coupled \Ill, L15 lo single-tuned circuit
LIB, 027.

Provision is madc for the connection
oi an external aerial. via. IrF. filter L1,
63, to S.W. coupling coil L15 (Model
210ll only), M.\\'. coupling coil L3, and
L.W. bottom capacitance coupling 05.

The complete R.F. and oscillator circuit
of Model 2IOU is drawn to the loll of
the main circuit diagram bolow.

First valve (V1, Mullard UCHA!) is a
triode Iiexodc operating as lrcquemy
changer with internal coupling. Single
oscillator anodo (UII L9 is tuned by 029
for M,\V. and L.\V. operation. Parallel
trimming by 018 (31.W.) and 011, 028
(L.W.); series tracking by 013 (M.W.
and L.\V.). Iii-ai'lion Coupling from grid

Sup but": to Wi
El , ' ,gclabl

PHILIPS .-

Cov 'cilso Mo:

circuit by L8, with additional coupling
across the common impedance of tracker
013. In Model ZIOU, the S.Wi coil LID
is tuned by 620. leaction coupling com-
prises a double resonant circuit L11, 031,
L18 which resonates at both ends of the
band to maintain a constant oscillator
output over this range.

Second valve lV2, Mullard UP) is a
variablormu ILF. pcntode, operating as
intermediate frequency amplifier with
tuned transformer couplings 08, L10, L11,
cs and cm, L12, L13, (:11.

Intermediate frequency 410 kc s

Diode signal dotcctor is part of double
diode triudo valve [V3, MuIllrd UBCM).
Audio iroquency i-omponent in rectified
output. is developed across volume control
R9 and passed via. 019 to grid of iriode
section. In Model ZIOU, tone correction
at low level settings of the volume con
trol is provided by R11, 833.

I).C. potential developed across the
volume control is fed back as bias to V1
and V2, giving automatic gain control.

l/ -- Par-z?! ial HI»;
->
1.on
A ; c5.
.1
c3
(0V2
5.6.
513 i .
L IS Lib C3 3
.-
5 L3 su<
IC4 L4 .
L5
L6.
L is A.G.C. l lore E
E} i
The section of circuit diagram above is for Model 210U and shows the extra coils Circuit diagra
and switches used for the additional waveband to cover SW. The remainder of adjusmienr 1n
the 210U circuit is the some as that for Model 131U on the right, with the addition section of. [hr
of R23, C33, 3 rapped volume control and C34. Where components are the adjustment pl
i- same in boih muili-ls they have the same number here as in the main diagram. closes. L1 is