Bush TR130 Servicing Instructions

General Description: Models TR130 and TR130D are battery­ operated portable receivers, each using seven transistors and one crystal diode, and covering the Long and Medium wavebands. An additional range provides electrical bandspread of the high frequency end of the Medium waveband. Both models are electrically identical, differing only in presentation. Wavebands: L.W. band: 1070-1900 m. (280 to IS8 kc/s.). M.W. band: 187-S70 m. (160S to S2S kc/s.). B.S. band: 187-210 m. (160S to 1430 kc/s.). Battery: One 9-volt Ever Ready type PP9 or Drydex type DT9. The battery consumption is IS mA. quiescent and 2S mA. at average listening level. Transistors (Mullard Type): VTl (AFII7) Mixer/oscillator. VT2 (AFII7) I.F. amplifier. VT3 (AFII7) I.F. amplifier. VT 4 (OC71) Audio amplifier. VTS (OC81D) Driver stage. VT6 (OC81), VT7 (OC81) Push-pull output. Crystal Diode: CDl (OA90) Detector. Earpiece Socket: A socket is provided at the side of the receiver into which may be plugged an earpiece of 20-1000-ohms impedance. Alterna­ tively, this socket may be used with an external loudspeaker of Is-ohms impedance. Tape Recording: No special provision has been made, but the earpiece socket provides a low-impedance output source to which a tape recorder may be conducted. The connecting lead should be terminated with a resistor of about I S ohms. It should be noted that the internal loudspeaker will be muted when using this method of recording. CAPACITOR F42 DRIVE DRUM DRIVE CORn 106

base, then remove the battery. Separate the two halves of the cabinet by releasing the two fasteners contained within the mouldings, then lift the back section clear. (Note: Dismantling to this stage will permit the R.F. align­ ment procedure to be carried out.) Unscrew the two 4BA nuts retaining the chassis to the speaker pillars, then loosen the two self-tapping screws securing the top edge of the chassis to the die-cast lugs of the top assembly. Lift out the chassis, unsoldering the loudspeaker leads if required. Replace the chassis by reversing the above procedure. Replacement of Drive Cord: Note: About 36 in. of Terylene cord will be required for the new assembly. Remove the chassis from the cabinet as described in the dismantling procedure above. Carefully ease the scale pointer from its carrier then remove the four Phillips head screws securing the scale plate to the chassis. Lift the plate clear. Withdraw the circlip located on the end of the tuning spindle, then loosen the grubscrews securing the capstan to the spindle and withdraw the tuning spindle complete with knob. Lift the capstan clear, noting the position of the nylon bearing to ensure its correct replacement. Set the tuning capacitor so that the vanes are approximately half meshed. Now from a point half-way along the new length of cord, make a loop of one turn round the spigot contained within the drive drum, passing the cord ends out through the slots in the drum. Assemble the cord drive and then refit the capstan. Finally pass the ends of the cord through the eyelet, knotting them under tension from the spring-loaded pulley mounted above the Off/On volume control. Note: When refitting the scale pointer, ensure that it registers with the datum marks on the right of the scale when the tuning capacitor is fully meshed. Adjustment of RV3: The replacement of components in the output stage may necessitate the resetting of RV3. This may be done by setting an AVO model 8 to the 50 /LA. D.C. range, and connecting it across R30, observe correct polarity. With the volume control set to minimum, adjust RV3 in accordance with the table below: Ambient temp. °C OF 18 65 23 73 28 82 33 91 Meter reading (50 /-,A. f.s.d. 9'24 1l'08 12·8 15'04 Equivalent I. in mA. of mV. (across R30) output pair 23'1 7'0 27'72 8'4 32'01 9'7 37.62 11'4 Alignment Procedure: Equipment required: An A.M. signal generator to cover 158-1605 kc/so An output wattmeter with a range 0-1 watt to match 15 ohms impedance. A non-metallic trimming tool for adjusting the iron cores and R.F. trimmers. A 10-pF. capacitor for injecting R.F. 107

8'2 kO-resistor for temporarily desensitising the receiver under conditions of interference. If the cabinet back is removed, R.F. alignment may be carried out without taking the chassis out. The chassis must be withdrawn, however, for I.F. alignment. The signal generator should be switched on about 15 min. before commencing the alignment. Connect the output meter to the receiver by means of the earpiece socket if a suitable plug is available. Set the receiver volume control to maximum, and the tone control to maximum treble response. During the alignment the signal input should be adjusted to maintain the output at 50 mW. (20 mW. if the loudspeaker is left in circuit) each time a trimming adjustment is made. I.F. Alignment: Note: The outer peak is the correct one for all I.F.T. adjustments. Switch the receiver to the Medium waveband and set the tuning pointer to about 300 m. Set the signal generator to 470 kc/s., modu­ lated 30 per cent. at 400 c/s. Connect the output via a o· I -mfLF. isolating capacitor to the junction of RI and CS, the chassis being the return point for the signal. Align I.F.T.3, I.F.T.2 and I.F.T.I, in that order, for maximum audio output. Align each transformer once only. R.F. Alignment: Notes: Ensure that the tuning pointer is in line with the datum marks on the right of the tuning scale with the tuning gang fully meshed. The signal generator should be connected to the aerial socket via a 10 pF. capacitor. Under conditions of interference, the receiver may be temporarily desensitised by connecting an 8'2kO resistor between the junction of R7 and RII and the chassis. Operation 1 2 3 4 5 1 2 3 Waveband M.W. M.W. Sig. gen. frequency (mod. 30% 400 c/s.) Oscillator Circuits 600 kc/so 1500 kc/so I Tuning pointer setting 500 m. 200 m. Repeat operations I and 2 and check calibration L.W. 214 kc/so I 1400 m. I B.S. 1439 kc/so Luxembourg· B.S. 1500 kc/so Carolinet M.W. M.W. Aerial Circuits 600 kc/so 1500 kc/so 500 m. 200 m. Repeat operations I and 2 for optimum gain at both points AdjJstfor maxtmum output CI6 L8/9/IO C40 L2/3 Cl L.W. 214 kc/so I 1400 m. C6 B.S. 1500 kc/so Carolinet C3 • Set the pointer to be coincident with the letter" m " of this station name. t Set the pointer to be coincident with the letter" 0 " of this station name. 108

RI 47 SA, d SA &. 4 ţ h I 3-10, Cl .. , 0 C4 C6 I 2 -25, 16 P HO I C9 '022 Ob' CI4 , )-)0, CCLCURED SFOT __ '-7"'-----' IfTl COil BASE VIEWED ON PINS (1I4,LIS) F45 I 1. __ _ _ _____ _ _ --ŧ CiRClIIT SHOWN WITH SWITCHES IN 1'1 ..... POSIT lOM. TOP a'.CSPRlAD MW PUSH BUTTON SWITCH 5 HOWN IN 1'\ .... POSITION VIEwED FIICM SIDE r -- I I CI8 -+' 2S op I • Cl6 Cl7 HOp )10, J,;---- 10 '''I NJV ,ll CťV R9 C10 680 ·1 1111 ISK Cll ·1 Rll 4'7Ũ C2) nop I RI4 C24 IK ·1 ŦVI 10K 09 .47 ? , 2 :F--- :-r==(==:!J 5 A J , fERRITE AERiAl (LI-U) tr-;@A RI7 8lK C 28 -I COl 01.90 8- RlO 5-OK VH OC 71 1119 680 r al5 RB 470 )9K T 1 4 02 10 @ e '8 VT 5 OC61D e 11 Z4 11 27 S'H 270 "'n S.a. b cO RZ9 150 CB 100 RO 1·5 - 5K 04 .1 R 28 HK "Y-l '-. tOLOUflED CASE SPOT YTI-l VH-7 eASES Of TRANSISTORS osc. COl l VIEWED FROM TOP IL8-LI0) \ , DRIVER TRlM SfORHER (T.I) VIEWED fROM TOP 3 L.:J cJ 2 4 f:::J cJ r J 5 2 __ . ...5...]' OUTPUT TRANSFORMER (T.2) VIEWED FROM Tor CIRCUIT DIAGRAM-BUSH MODELS TRI30 AND TRI30D .31 lOll. R)Z 150 NOTE S "? 06 n+n zoo ,..--<"* 1 JK LSI + 9V © 4:J I JK I ¯ Al.nRNATr.'r rA"'_E socdT CO .... IeT""'. ..HaM ...... PII.,SIIC *I(ET I VOLTAGES SHOWN ARE NEGATIVE WITH RESPECT TO CHASSIS AND MEASUREO WITH AVO N.8 UNDER NO' SIGNAL CONDITIONS AND WITH VOLUME (ONTROL SET TO ZERO Z ALL VALUES Of RESISTANCE IN .HMS AND ALL VlL°S OF CAPACITANCE IN ,..F UNLESS OTHERWISE STATED.