EKCO P-148 Portable Receiver Service manual

SERVICE MANUAL
Price 6d.
CONFIDENTIAL.— For the Information
of Ekco Registered Dealers only.
NOT TO BE COPIED.
MODEL P-148
PORTABLE RECEIVER.
GENERAL DESCRIPTION.
Model P148 is a battery operated light-weight portable using four Mullard valves.
| Vaives: VI (H.F. amplifier)——VP2B H.F, pentode: V2 ([caky-grid detector) —PM2HL triode ; V3 (L.F. amplifier) —PM2HL
triode; V4 (output valve) —PM22A output pentode.
Accessories: H.T. hattery—Drydex H1146; Accumulator—Exide JSK2.
Consumption: HT 7 ma.; L.T.—.5 amp. |
CIRCUIT DETAILS.
Frame acrials LT (MLW) and LZ (L.W.) arc switched scparately between grid and filament of V1, which is trans-
former coupled to V2. CI& and R3 ensure smooth reaction.
— 215 resistance-capacity coupled to V3, V3 transformer coupled to V4. Headphone sockets are connected across
primary ot output transformer T2 in anode ‘circuit of V4, (Speaker silencing switch provided.)
Bias for V1 and V3 is developed across RIO, and for V4 across R10 and R11 in common HT. negative line,
VALVE VOLTAGE AND CURRENT READINGS.
Valve Type Anode
Filament Bias Notes.
Ve VP2B | 53 у. lm.a, 21 v. 3m.a.j.I4amp. | 7v. Voltages measured on’ high resistance meter. (Chassis
ra. = negative). |
ve PMZHL {58 v. Sma. Voltage readings for V1, V2 and V3 depend on meter
> | , resistance, Current readings are more reliable.
VS MERE 08 у. та. ———z—— 1 amo. Tv Bias measured with receiver switched on and all valves
V4 PM22A [83 у. 4 та. 188 v. .75 mal 15 атр. | 2v. | 11 sockets,
Resistances. All resistances are indicated in Figs, 1—4.
Re-ganging. Tunc receiver (preferably during daytime) to a station between 220 and 300 metres which is only just
audible with maximum reaction. Adjust gang trimmer (C2) for maximum volume, meanwhile cnsuring that receiver
does not rotate on turntable.
If pointer reads incorrectly, loosen centre screw and move celluloid dise through appropriate angle.
Note. Trimmer was fitted to C8 in early receivers. This should be left fully unscrewed.
Under-chassis service, Moulded escutcheon ¢an be removed for servicing underside of chassis.
Remove cabinet back, hatteries, valves, station-scale and control knobs (two grub screws in large knob). The
escutchcon 1s held by two screws (yellow washers) one inch from base of cabinet, and two nuts under top of cahinct,
If necessary, screws holding chassis corners may be removed, allowing chassis to he fully exposed.
Note, Ensure that pointer indicates correctly when remounting celluloid disc.
Speaker. If speaker requires service, remove Laffle, output transformer and speaker complete, otherwise silk may
be damaged in remounting speaker.
PRICE LIST. Е
Gang (C1, C2, C8 (C7813 10/6 Escutcheon 117802 4/6 C3 A3844 1/- C14 A4109 1/- К5
B7823 Gl.
M.W. frame (Li) D[P1580 3/- (green or red) C4 DP1600 9d. C15 A3844 1/- КО B782> 94.
H.¥. trans, (1.3/6) 1)P1569 5/- Speaker 137803 17/6 C5 A384 1/- (Clo A4109 1/- R7 В7825 904.
Intervalve Tuning knob DPI1583 2/- C6 B7822 1/9 C17 B7821 1/9 RR 17825 Of
transformer (U']} DPI1566 3/6 Vol. control C7 B7815 2/6 Cl8 A5747 Od. KO R/R825 94.
Output trans. (T2) 1P6=4/1 7/6 knob DIZ 9d. CIO A6516 Id. RI A6122 9d. RIO B7825 9d.
МИС switch (51/5) B7814 2/6 Switch knob. 1P1581 9d. C11 57822 1/9 R2 B7009 94. R11 В7824 9d.
Cabmet (inc. back | Scale A7811 64. CI2 A6516 9d. R3 B7825 9d. R12 B7R25 9d.
and LW. frame). bP1577 25/- Celluloid disc A7810 6d. CI3 В6869 1/-- R4 B7825 94.
Prices are refatl and subject to alteration without notice. Orders must quote pari numbers indicated above.
IMPORTANT NOTE.—Enquirtes concerning service manuals should be addressed io Head Office
orders, set repairs and service correspondence will be handled by the depot in whose area you are located,
"SERVICE," E. К. COLE LTD., EKCO WORKS, SOUTHEND-ON-SEA.
Scottish Service Depot: 27, Cadogan Street, Glasgow, C.2.
Manchester Service Depot: Bombay House, 59, Whitworth Street.
(Goods address : 7, Bombay Street.)
Bristol Service Depot: 14, Redcross Street.
Component
Telephone: Southend 49491.
Telephone ; Central 5357/8 /9.
Telephone: Central 6711 /2.
Telephone : Bristol 22269.
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Fig. 2. Top of chassis. Coil resistances are indicated.
| MITE TRAS TACIZ. YELLONTOE" SOCKET.
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ee Ste _ | | = REAR EOLE OF CABINET — |
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HF TRANS CONNECTIONS
IMERSURE VAL2)TO TAL |
o TO BRIDGE OF SPEAKER RE,
SILENCING SWITCH.
LUE TO PHONE SOCKET AnD BLUE TO EHH,
ay TOSPERKER AND 3
OUTPUT TRANSFORMER TAC PANEL? RESISTANCES: PRIM [TRCS P-01-1.350n.: SECITACS M-N- 25. wavechanse switch,
Fg. 8. Underside of chassis. Connections and resistances of intervalue and output frame aerials and Н.Е.
transformers are shown. transformer.