FARNELL INSTRUMENTS LTD. WETHERBY TITLE L30/2 & LT30/2 CIRCUIT DIAGRAM SHEET 1 OF 1 SHEETS DRAWING No. 2SZX0090 USED ON 847 852 * = Not fitted (R2) Note: voltages measured with respect to control board pin 7, unless otherwise shown, using a 20000 Ohm/V meter, at nominal input voltage, Output 30V 2A CONTROL BOARD No. 2SZ0345 SW203 CV Constant Voltage C1 (Channel 1??) On Base On the L30/2 the earth terminal is on the baseplate. I CONST OP- Output - O/P Output BOM Bill of Material Parts List C1 0.1 250V C2 47µ 63V C3 1µ 100V rather big value C4 1000pF 500V C5 100pF 500V C101 0.22µ 160V C102 4800µ 63V C204 470µ 63V rather big value at the output terminals D1 1N4148 D2 1N4148 D3 1N4148 D201 1N4148 D202 MR752 D203 MR752 F1 160mA T F101 1A on L30/2 F101 2A on LT30/2 F102 2A IC1 UA741 µA741 IC2 MC1458C dual universal opamp LED101 BIM556R Input Indicator LED102 BIM556R overload indicator M101 Meter 1mA? full scale 30V and 2A scales MR101 Rectif KBL02 MR1 Rectif W02M P1 5k Meter cal volts (volts calibration) P2 2k Set IO()=/P volts max. (maximum Output Voltage) P3 5k Set C/L Max. (maximum Current Limit) P4 200 Meter cal current (current calibration) P101 5k Set O/P volts coarse P102 5k Set O/P volts fine P103 5k Set C/L (Current Limit) R1 470 6W R2 --- * not fitted R3 1k8 R4 27k R5 18k R6 470 R7 22k R8 22k 0.5W R9 560k 0.5W R10 22k R11 22k R12 33k 0.5W R13 10k R14 10k R15 1k 0.5W R16 680k R17 6k8 R18 330 R19 330 R20 270 R21 1k5 R22 4k7 R23 4k7 R24 220k R25 10k R26 82k R27 82k R28 10k R29 220 0.5W R30 5k6 R101 R102 3k3 1W R103 R104 R105 R106 R107 120 0.5W R108 0.5 6W R109 0.5 6W R110 0.5 6W R111 0.5 6W R201 1k8 0.5W for LED201 R202 R203 R204 0.25 2.5W R205 R206 1k2 1W SW101 2pole Mains SW102 2pole Meter Volts/Amps SW103 channel 2? SW104 2pole Output On/Off SW105 channel 2? SW203 1pole CV Constant Voltage? connected to "I CONST" terminal of open, full output voltage will be present on output terminals TX101 Mains transformer PRIMARY: 110+110/130, SECUNDARY:40V 3A, 36V 0.5A VT1 BC212L current mirror VT2 BC212L current mirror VT3 2N3053 output predriver VT4 BC182L overload indicator LED disabler VT101 2N5294 2N3054 would have been nice between 2N3053 and 2N3055 VT102 2N3055 output stage VT103 2N3055 output stage VT104 2N3055 output stage VT105 2N3055 output stage Z1 BZX61C15 Z2 BZX85C5V1 Z3 BZX85C5V1 Z4 1N823 6.2V reference Components numbered 2__ are on the output circuit board. Resistor values in Ohm Capacitor values in µF unless otherwise stated LT30/2 supply 2 as supply 1 but with LED101 omitted The mains transformer is shown connected for 240 V input. For 110/130V input, the 1-110V windings are connected in parallel as shown: (on both transformers on LT30/2) TRACED CHECKED C 11.7.? 4615? J.S. B 1.7.78? 4812? 4813? DRAWN ISS DATE MOD No J.N. A 25.6.78? control board has 2x 12=24 connections: 1 LED102+ overload indicator positive 2 LED102- overload indicator negative 3 from P3 to current poti P103 4 regulation from VT3 to VT101 5 unregulated power voltage from MR101 to VT3 6 P103w wiper of set current limit poti to R27 7 0V control ground reference (connected to positive output terminal) 8 TP test point 15V regulated control supply from Z1 9 TP test point -5.1V -5V1 regulated control supply from Z2 10 current sense from R204 (shunt) to R25 11 fine poti P102 to R9 12 from P1 to SW102 13 positive output (from SW104 to R28, R29) 14 from P4 to SW102 15 from R4 to negative output terminal (-O/P-) 16 feedback from R12 to SW203 17 TP feedback test point (0.0V) 18 feedback compensation from R15 to SW203 19 coarse poti from P101 to R8 20 TP test point 6.2V 6V2 reference voltage from Z4 21 from P2 to both voltage potis P102 and P102 22 TP test point 45V (unregulated control supply) 23 36VAC input from TX101 to MR1 24 36VAC input from TX101 to MR1