Decca tvs 11 service manual

Page 2

INTRODUCTION

Primarily intended to enable blind persons to hear
television sound on u.h.f., the Decca RNIB/TVSII rec-
eiver can be tuned to any one of four pre-selected Band
IV or V television channels. Simplicity of operation is
ensured by the placing of all user controls on the cabinet
top. These consist of four channel pushbuttons, rotary
volume and a push-on/push-ofl' mains switch. The
receiver is suitable only for a.c. mains operation.

At the rear of the receiver is a panel incorporating a
5-pin socket for feeding the receiver output to an external
amplifier or tape recorder, an earphone socket, and two
preset controls allowing an output level and tone thresh-
old setting. There is also a coaxial socket allowing the
receiver to be used from an external TV aerial, instead of
from the receiver telescopic aerial, the lead from which is
normally plugged into the coaxial socket.

Essentially the TVSll comprises a standard u.h.f.
varicap-tuner, with a separate station selector unit, which
feeds a specially-designed I.F. unit in which the sound
intercarrier is extracted from the selected TV station
carrier frequency. Audio output from the sound FM
discriminator is passed to a power output stage, which is
on the same p.c. board as the LP. stage. Four integrated
circuits are used.

A separate p.c. board contains the receiver stabilised
power supply unit. The complete TVSll is housed in a
vinide-covered wood cabinet, fitted with a carry-
ing handle.

SPECIFICATION

Power supply 230V 50Hz a.c. mains only

Frequency range 470 to 859MHz (U.H.F. bands IV and
V, TV channels 21 to 68)

Intermediate frequencies TV sound 33.5M Hz; sub-carrier
6MHz.

Transistors BC 1 09, 200185

Integrated circuits MC1330, MC1352, TBAél lB,
TBA7 50, SN7650-2

Diodes 1N4003, 1N542B, 1N4004, 1N4 l 48

Audio input Nominal 1 watt (sinewave)

Input Aerial, 80 ohm unbalanced (via
coaxial socket)

Outputs lSOmV a.f. into load not greater than

Skilohms (Via 5-pin DIN socket)
Earphone (via 3.5mm jack socket)

Loudspeaker Sin (127mm) round, impedance 12
ohms.
Dimensions Height Width Depth

7gin 11%in 3%in
(194mm) (301mm) (98mm)

Weight 8§1b(3.8kg)