Decca tp 90 a service manual

Page 1

O Ilifie Technicll Publications Ltd.. 1967

TRADER" SERVICE SHEET

1825

ECCA TP90/A a.m./f.m. transistor
portable radio receiver covers m.w.
(13376-571111), LW. (1150-2006111) and

v.h.f. (87'5-101Mc/s).

It has an internal ferrite rod aerial for
medium and long wavebands and a socket
for an external aerial. For v.h.f. a telescopic
aerial is fitted.

Nine transistors and five diodes are
incorporated in a circuit dispersed over
four printed circuit panels, made up as
follows: V.h.f. tuner, mains chassis,
preamplifier and audio. Plug and socket
connections are used throughout with
the exception, v.h.f. timer to main chassis.

Controls consist of four press-buttons
for waveband switching and on-off, and
two knobs, one each for volume and
tuning. All are situated on the top of the
case.

Sound output is by a Sin round speaker
and a socket is provided for an earphone
or external loudspeaker of 1552 impedance.
The internal loudspeaker is muted when
this socket is in use.

Supplement to
Electronic Trader.

DECCA TP90/A

A.M./F.M. Transistored Portable
Radio Receiver

A socket for the connection of a tape
recorder is also provided. This gives
direct access to the top of the volume
control via a blocking capacitor.

Power is supplied by 2. 9V (Ever-Ready
PP9 type) battery.

The whole is contained in a vinyl covered
case with carrying handle.

Battery replacement is facilitated by the
removal of the case back after turning two
plastic 00in slotted screws one quarter turn.

TRANSISTOR ANALYSIS

Voltages given in the table opposite were
obtained from information supplied by the
manufacturers. They were measured with a
model 8 Avometer with respect to the
negative line.

Three-quarter front view of the Decca
TP90/A.

(Continued overleaf, col. 1)

C "1 2 347 4 a "1,5 5 9 16,11,14 IS 1: t2 zqztzmsms 19 51 65 23 24 27.26 so,2e,29,31,3112,34
R 1 5 2 4 5.6 25 7,3 0 9 11 13
Telescopic xii
aerial S] R 5 l i
Ext-mm l 653 I: 061 C65
aerial o 1
socket lcté t RS 10
R6
l v
I-
C l l f 203
Memo 1
ceriol HF TRS
01 54 ._r
l
l
1
c2 " _
- m I'cu

I'

TRl
Bust: /

TR2,3,4.S

fl\ Emltteflollzctor
E . ,,
mutter . ' Collector .' .j Emit.

mterlwd b
shizld Bose.

Interleod
Shield

mollcctor
MEmmzr .j
o urzd Whte
Bose I

TRé 7R7. 8.9

mcmlzctor

Circuit diagrampfthe Decca TP90/A a.m./f2m. transistor

lo
Base 5 pet spot

Page 2

Electrical and

, 13 October 1967 DECCA 1825
-.- TP90A
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11.1 53011 F4 R40 Mm 133 C26 560pF C2 C55 500113 32 L9 _ (:2
R2 10011 F4 R41 1000 D3 C27 1sopF c2 C66 02211F 31 1.10 - 31
R3 1m F4 342 47m 153 023 2381211 F4 057 o-111F 33 L11 _ 32
34 am 124 34: 2-230 D3 (:29 sopF 31 C68 mm 53 1.12 _ 32
35 mm F4 R44 1000 D3 C30 186pF 31 C69 mm 35 L13 _ 133
R6 10m F4 R45 2-2sz D3 C31 30pF 31 C70 10ch E3 L14 1552 1
R7 3339 C1 R46 1000 D3 C32 5503!? (:2 C71 10ch E3 CH1 ~ C1
35 581m 31 347 2-2:) 1:13 C33 ISOpF C2 C72 500111: 33 CH2 _ c2
39 2200 C1 3411 2-29 D3 C34 150pF 31 C73 soouF 31
51127015 1 151213 11 512 1'1; 51 81: 51811: 51
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R12 2-2112 C2 C37 1031' 32 _ "Indians:
R13 6800 El _ C38 1,500pF 32 Calls and Transform": D1 - 32
R14 55m B2 Cancun": (339 0-1111? 32 L1 .- F4 D2 - 32
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317 47012 32 c3 47pF F4 C42 1,000pF 32 L4 _ F4 D5 - C:
313 15351 32 c4 1,000pF F4 C43 mm 32 L5 3 F4 51.511 - 31
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R38 551:: 153 C24 o-OZuF 31 C63 1,000pF 32 TR9 01:51 9-0 5-9 4-5
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VIEWED FROM UNDERSKDE OF BASES