Philips 215 a service manual

Page 1

STRICTLY CONFIDENTIAL:

FOR PHILIPS SERVICE DEALERS ONLY i
O
{COPYRIGHY I938

SERWCEDOCUMENTAWON
FOR RECBVER TYPE
215 A ;
Wavebandswifch

Vqume confrol
and mains switch M I

D2944

Tuning

FOR A.C. FEEDING
EXECUTIONS 2I5 A, 215 A-I3, 215 A-25, 2I5 A-33

GENERAL DATA:

This superhet receiver is provided with:
Seven tuned circuits.

Bandpass filter pre~selcctiom

Filter against second-channel interference.
Delayed A.V.C.

Permanently energised moving coil speaker (type
9648)

Connection for gramophone pick-up

Voltage adapter with automatic indication on the
rear panel, for voltages of 105-250 volts.

WAVE BANDS.

Short waves: 16,7- 51m( 18- 5.9Mcls
Medium ,, 2 198 - 585 :11 (1510-512 chs)

Long ,, : 708 4000 m ( 425-1550 chs)

KNOBS.

On left-hand panel: Volume control + mains
switch

On front panel: Tuning
On right-hand panel: -Waveb3nd switch.
WEIGHT: 6.9 kg net (including valves).

DIMENSIONS: height: 25 cm
width: 42 cm (including knobs)
depth: 20 cm (including knobs)

66.994.50l1.05

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".215A, \
~ x

Description of circuits.

A.
I.

III.

IV.

II.

H.F. part.
Long wave band.

Aerial coil: 56 + 57.

lst bandpass filter circuit: 58 + 39, C15, C16,
C7, C10 (coupled with aerial co.l, inductively
by coupling between SS + $9 and $6 + S7,
capacitively by C14).

2nd bandpass filter circuit: 810 + 511, C15,
C16, C8, C11 (coupled with lst bandpass
filter by C15 + C16). (Coupled with the
input grid of L1 via R14, to prevent parasitic
oscillation).

Oscillator circuit: 814 + 516, C19, C23, C12,
C9. ,

Reaction coupling coil: SIS + 517, inductiv-
ely coupled with $14 + 516.

Medium wave band.

Aerial coil: 36.
lst bandpass filter circuit: 58, S30, C16, C7,
C10 (coupled w.th aerial coil: inductively
through coupling between $8 and 56, capaci-
tively by 514).

2nd bandpass filter circuit: 510, 531, C16,

C8, C11 (coupled with first bandpass filter
capacitively by C16, inductively by
coupling between $30 and S31). (Coupled
with input grid of L1 via R14, to prevent
parasitic oscrllation).

Oscillator circuit: 514, C20, C31, C9.
Reaction-coupling coil: $15, inductively cou-
pled with 514.

Short wave band.

Aerial coil: $12.

Input grid circuit: 513, C32, C8 (313 is in-
ductively coupled with $12). (Couplng with
input grid of L1 via R14, to prevent parasitic
oscillation).

Oscillator circuit: 518, C9 (coupled with 1st
grid of L1 via C29).

Reaction coupling coil: $19, inductively cou-
pled with 318.

Image frequency filter: C17 and $30 with the
Is: bandpass filter circuit.

LF. part.

LF. transformer : 320, C21, 821, C22.
LF. amplifier valve: L2 (AF 3).
LP. transformer : 522, C23, 323, 324, C24

Detector.

Detector circuit : Anode detector (=: lst
diode of L3). 324,
(C25), R8, R10, catho-
de L3.

12

D. LF. Amplifier.

E.

F.

From the volume control R10 the detected
L.F. voltage is applied via C26 and R11 to
the grid of L3, then amplified here and pas~
sed via the speaker transformer 825, $26 to
speaker 527.

Automatic volume control. \

The H.F. voltage on the anode of L2 is ap-
plied to the second detector diode of L3 via
the capacity of two intertwined wires.

The detected DC. voltage produced in this
way on R5 is applied via R9, 521 to- the input
grid of L2 and via R9, R4, 511, 310, R14,
to the input grid of L1, in which way the
negative bias, and thereby also the amplifi-
cation of L1 and L2 are regulated.

When the set is switched to the short wave
band only the amplification of L2 is con-
trolled.

The 2nd detector anode of L3 is made nega-
tive with respect to the cathode by the voltage
drop across R13 + R15. In this way the
automatic volume control only comes into
operation when the strength of the incoming
signal is above a certain value.

Feeding.

Feed transformer: 31, 32, S3, S4.

Anti-hum condenser: C38 (not in sets with
transformers having separate windings).
Rectifier valve: L4 (AZ 1)

Smoothing filter: C1, R2, C2.

The positive voltages for the valves are taken
from C2.

Voltages for L1:

Va : via 820.

Vg3,5: via R3; decoupled by C4.

VgZ : via R3, (317, $15, 519); decoupled by
C4 (see also under automatic volume
control).

Vgl : voltage drop across R1; decoupled by
C13.

Voltages for L2:

Va : Via $22.

VgZ: Via R3; decoupling by C4.

Vgl: Voltage drop across R7, decoupled by
C6 (see also under automatic volume
control).

Voltages for L3:
Va : taken from C1, via 525.

VgZ: from C2.

Vgl: voltage drop across R13.

Va (2nd detector anode): voltage drop across
R13-R15; decoupled by C28.