McIntosh-MC303-pwr-sm维修电路原理图.pdf

MC303 MC303 POWER AMPLIFIER SERVICE MANUAL SERIAL NO. ZH1001 And Above Performance Specifications .2 Notes .2 Rear Panel .3 Section Location .4 Block Diagram .5 Interconnection Diagram .7 - 8 Backup Power Suppy Schematic and PCB .9 - 12 Control Schematic and PCB .13 - 16 Input Channel 1-2 Schematic and PCB .17 - 20 Input Channel 3 Schematic and PCB .21 - 24 Capacitor Schematic and PCB .25 - 28 Heatsink Schematic and PCB .29 - 34 Terminal Schematic and PCB .35 - 38 Display Schematic and PCB.39 - 44 Meter Control Schematic and PCB .45 - 46 Meter Light Schematic and PCB .47 - 48 Parts List .51 - 55 Repacking Instruction .57 CONTENTS RadioFans.CN 收音机爱 好者资料库 2 1. Unless otherwise noted, all voltages indicated on the schematics are measured under the following conditions: a. AC input at rated voltage marked on rear panel. b. All voltages are +/-10% with respect to ground. A high impedance (10 megaohm) voltmeter must be used. 2.Unlessotherwisespecified: a. Resistor values are in ohms. b. Capacitor values are microfarads (uF). c. Inductor values are in microhenries (uH) 3. On PC board drawings, Square pad indicates: a. Polarized Capacitors - Positive b. Diodes - Cathode c. Others - Pin 1 4. WARNING Parts marked with the symbol have critical characteristics. Use only replacement parts recom- mended by the manufacturer. NOTES PERFORMANCE SPECIFICATIONS Specifications Power Output Minimum sine wave continuous average power output per channel, all channels operating: 300 watts into a 2 ohm, 4 ohm or 8 ohm load Output Load Impedance 2, 4 or 8 ohms Rated Power Band 20Hz to 20,000Hz Total Harmonic Distortion 0.005% maximum harmonic distortion at any power level from 250 milliwatts to rated power, 20Hz to 20,000Hz Dynamic Headroom 1.8dB Frequency Response +0, -0.25dB from 20Hz to 20,000Hz +0, -3dB from 10Hz to 100,000Hz Input Sensitivity (for rated output) 1.7 Volt Unbalanced 3.4 Volt Balanced Signal To Noise Ratio (A-Weighted) 112dB below rated output Intermodulation Distortion 0.005% maximum, if the instantaneous peak power output does not exceed twice the rated power output for any com- bination of frequencies from 20Hz to 20,000Hz. Wide Band Damping Factor Greater than 40 Input Impedance 10,000 ohms Power Guard Less than 2% THD with up to 14dB overdrive at 1,000Hz Power Control Input 5VDC - 12VDC Power Control Output 12VDC, 25mA maximum, delay 0.2 seconds Power Requirements 100 Volts, 50/60Hz at 12 Amps 110 Volts, 50/60Hz at 11 Amps 120 Volts, 50/60Hz at 10 Amps 220 Volts, 50/60Hz at 6 Amps 230 Volts, 50/60Hz at 6 Amps 240 Volts, 50/60Hz at 6 Amps Standby: Less than 1 watt Note: Refer to the rear panel of the MC303 for the correct voltage. Overall Dimensions Width is 17-3/4 inches (45.09cm) Height is 12-3/8 inches (31.43cm) including feet Depth is 22 inches (55.88cm) including the Front Panel and Cables Weight 155 pounds (70.3 kg) net, 180 pounds (81.6 kg) in shipping carton Shipping Carton Dimensions Width is 31 inches (78.74cm) Depth is 28 inches (71.12cm) Height is 17-1/4 inches (43.82cm) RadioFans.CN 收音机爱 好者资料库 MC303 REAR PANEL 3 RadioFans.CN 收音机爱 好者资料库 4 SECTION LOCATIONS RadioFans.CN 收音机爱 好者资料库 MC303 BLOCK DIAGRAM 5 RadioFans.CN 收音机爱 好者资料库 6 NOTES RadioFans.CN 收音机爱 好者资料库 POWER AMPLIFIER MC303 MT3 GND MT3 GRN MT3 BLU GND J1 1 12 J12 1 12 GND MT2 GRN MT2 BLU GND J1 1 12 J11 1 12 GND MT1 GRN MT1 BLU GND J1 1 12 J10 1 12 + - MT2 PG2 LT GND PG3 LT PG1 LT MT3 LT MT2 LT MT1 LT J9J8 1 18 PG2 LT PG COM PG COM PG COM PG3 LT PG1 LT MT3 LT MT2 LT MT1 LT 1 18 GND GNDGND GNDGND PG COM PG COM PG COM MT1 FB+MT1 FB+ MT1 FB-MT1 FB- MT2 FB+MT2 FB+ MT2 FB-MT2 FB- MT3 FB+MT3 FB+ MT3 FB-MT3 FB- MT1 1 2 3 1 3 J15 +3V 1 2 MT3 | +| J13 +3V 1 2 MT1 | +| J14 +3V 1 2 MT2 | +| METER LIGHTS OFF SW 1 AUTO POWER CONTROL OFF SW 2 REM ON FP OFF FP ON GND J4 J7 GND ML OFF J6 1 12 J1 1 12 1 J1 6 PG THRM MET MUTE -15V +15V 1 J3 6 1 J2 -15V +15V 6 MUTE MET THRM PG -15V FP ON GND FP OFF MET LT MUTE ILLUM J5 1 18 PWR RLY GND +15V +15V +5VBU GND GND -15V -15V +5VBU +15V GND +5V +5V GND PWR RLY PWR RLY GND GND GND +5V +5V +5V GND +5V +5V GND PWR RLY PWR RLY GND GND GND +5V +5V +5V 1 18 -15V FP ON GND FP OFF MET LT MUTE ILLUM PWR RLY GND +15V +15V +5VBU GND GND -15V -15V +5VBU +15V J14J15J11 J22 J10J13J12 J21 WHT/VIO ORN BLK VIO GRY WHT ORN BLK/GRY J8J9J4J3J6J5 J1J2 BLK WHT BLK F1 J5J4J6 BLU GRN BLU T4 C1 RED RED D1 J4 J5 RED GRN J6 YEL J7 1 2 -75V +75V J3 -75V +75V J2 -75V +75V J1 -75V +75V 1 2 -75V +75V J5 1 2 -75V +75V J5 J8 1 J9 5 1 J3 -15V +15V 6 MUTE MET THRM PG 1 J2 8 Ohm 4 2 Ohm 1 J1 4 -15V +15V AMP GND J6 J7 J4 VIO WHT 1 -15V +15V 6 MUTE MET THRM PG 8 Ohm 2 Ohm -15V +15V AMP GND J6 J7 J4 VIO WHT 1 J7 4 -15V +15V AMP GND 1 J6 4 AMP GND 1 J6 4 8 Ohm 2 Ohm J5J1 J2 J3 J4 BLK BLU RED ORN 1 J6 4 8 Ohm 2 Ohm J5J1 J2 J3 J4 BLK BLU RED ORN 1 J3 -15V +15V 6 MUTE MET THRM PG 1 J2 8 Ohm 4 2 Ohm 1 J1 4 -15V +15V AMP GND J6 J7 J4 VIO WHT 1 J6 4 8 Ohm 2 Ohm J5J1 J2 J3 J4 BLK BLU RED ORN 1 J1 4 AMP GND 1 J2 5 PC IN GND PC MET PC OUT GND GP1 GP1 GP1 J1 -15V +15V T1 T2 T3 +15V -15V MUTE MET THRM PG GND PC IN PC MET PC OUT GND 1 2 1 2 1 2 J5 1 J1 4 J3 J2 1 4 11 METER LIGHT 11 METER LIGHT 11 METER LIGHT 9 DISPLAY 3 CONTROL 2 BACKUP POWER SUPPLY 7 HEATSINK 7 HEATSINK 7 HEATSINK 4 INPUT CH 1-2 5 INPUT CH 3 8 TERMINAL 8 TERMINAL 8 TERMINAL 6 CAPACITOR 10 METER CONTROL LINE VOLTAGE 100V 110V/120V 220V 230/240V F1 F15AH 125V F15AH 125V T8AH 250V SB T8AH 250V SB BACKUP PCB JUMPERS J3-J8 J4-J9 J3-J6 J5-J9 J4-J7 J5-J6 .22uF OUTPUTS 3 COM 2 8 4 OUTPUTS 2 COM 2 8 4 OUTPUTS 1 COM 2 8 4 78 INTERCONNECT RadioFans.CN 收音机爱 好者资料库 910 2 BACKUP POWER SUPPLY 750975 SCH 1 1 1 GRY BLK/GRY BLK J15 J1 J2 3 1 4 2 K2 1 1 1 WHT WHT/VIO VIO J12 J14 J13 1 1 J10 J11 AC N AC FUSE 100V 20V 100V 20V 1 J3 1 1 J4 J5 1 1 J9 J8 D1 POWER TRANSFORMER PRIMARY 240V220V120V 2 6 8 4 1 3 5 7 PRIMARY T1 3 1 4 2 K1 100V t RT1 t RT2 J7 1 3300pF C1 J6 1 J16:1 J16:2 + RLY TP - TEST ONLY NO CONNECTION 2 13 IN OUT U1 .47uF C3 .3A t R1 3300uF C2 PGND 1 ORN J21 9 PWR RLY 1 ORN J22 1.82k R2 31 2 Q1 PWR TRANSFORMER THERMAL SWITCH J23:11 9 +5VBU GND 9 J23:1 J23:2 TO DISPLAY FROM DISPLAY J23:12 J23:3 J23:4 J23:5 J23:6 J23:7 J23:8 J23:9 J23:10 D4 D5 D2 D3 F1 0V J4 12V RadioFans.CN 收音机爱 好者资料库 POWER AMPLIFIER MC303 1112 2 BACKUP POWER SUPPLY 750975 PCB RadioFans.CN 收音机爱 好者资料库 1314 3 CONTROL 750886 SCH 22.1k R3 47.5k R2 9 10 8 U1:3 4 5 6 U1:2 4.75k R6 +5VBU 4.75k R1 +5VBU J8:5 J8:4 FP ON FP OFF FROM DISPLAY PC M ET PC IN J9:3 +5VBU .1uF C3 TURN ON CONTROL 10uF C11 31 2 G D S Q4 AMP M UTING MUTE TURN ON DELAY 2.21M R11 1uF C8 9 10 8 U2:3 1M R16 .22uF C12 1 2 3 7 B+ GND 14 U2:1 +5VBU 31 2 Q1 31 2 Q2 .1uF C2 150k R10 4 5 6 U2:2 12 13 11 U2:4 AC DETECTOR +5VBU +5VBU .1uF C13 100k R14 31 2 Q9 22.1 R29 +15V+15V 31 2 Q13 10k R24 31 2 Q8 CONTROL OUTPUT 100k R25 POWER 4.75k R30 31 2 Q12 +15V 2.21k R28 .1uF C14 47.5k R22 -24V 5 PC OUT TO CH3 INPUT FROM CH3 INPUT 1 1 1 BLU GRN BLU 1.1A t R4 .047uF C1 3 1 2 IN OUT U4 3300uF C4 2 31 IN OUT U3 .1uF C9 100uF C7 .1uF C10 3300uF C5 100uF C6 D2 D3 D1 D4 -15V +15V J4 J5 J6 1.1A t R5 12 HS1 12 HS2 PWR TRANSFORMER SECONDARY 100k R7 -24V 1 2 3 7 B+ GND 14 U1:1 12 13 11 U1:4 22.1k R8 47.5k R9 +5VBUMETER LIGHT CONTROL +5VBU 5 GNDJ9:5 J9:4 9 PWR RLY 9 GND 5 5 9 9 J8:6 J8:9 J8:8 J8:2 -15V +15V9 9 +15V -15V +5VBU9 +5VBU 9 MET LIGHTS J8:3 J8:7 J8:1 9 MUTE MUTE TO DISPLAY J8:10 J8:11 J8:12 9 ILLUM J8:13 J8:14 J8:15 J8:16 J8:17 J8:18 J9:1 5 GND 5V 0V 0V5V -18V 0V 5V 5V 5V 12V 0V 12V 5V J9:2 -18V 5V 0V T4 RadioFans.CN 收音机爱 好者资料库 POWER AMPLIFIER MC303 1516 3 CONTROL 750886 PCB RadioFans.CN 收音机爱 好者资料库 1718 4 INPUT CH 1-2 750866 SCH 7A 7A GND 10uF C5 47pF C7 47pF C6 CH1 BAL TO UNBAL AMP AMP 1 TO CH1 HTSNK 10uF C4 10k R8 CH1 INPUTS 6 5 7 - + U1:2 47pF C8 4 2 3 1 S - + G J2 10k R9 +15V2 -15V2 +15V2 -15V2 1 2 J3 221k R7 221k R6 10k R5 20K R3 20K R4 7B 7B GND 10uF C10 47pF C12 47pF C11 CH2 BAL TO UNBAL AMP AMP 2 TO CH2 HTSNK 10uF C9 10k R15 2 3 1 - + 84 B+ B- U1:1 47pF C13 10k R16 221k R14 221k R13 CH2 INPUTS 4 2 3 1 S - + G J4 1 2 J5 10k R12 20K R10 20K R11 10uF C1 .1uF C2 .1uF C3 10 R1 10 R2 .1uF C14 .1uF C15 7A 7A CH2 HTSNK FROM 2.21 R18 2.21 R17 2.21 R19 2.21 R20 J7:1J7:2 J7:3J7:4J6:3J6:4 GP1 0V 0V 0V 0V 0V 0V RadioFans.CN 收音机爱 好者资料库 POWER AMPLIFIER MC303 1920 4 INPUT CH 1-2 750866 PCB RadioFans.CN 收音机爱 好者资料库 2122 5INPUT CH3 750887 SCH FROM CONTROL 3 GND +15V -15V +15V2 -15V2 7C 7C GND 10uF C6 47pF C8 47pF C7 CH3 BAL TO UNBAL AMP CH3 AMP TO CH3 HTSNK 10uF C5 10k R8 2 3 1 - + 84 B+ B- U1:1 47pF C9 10k R9 +15V2 -15V2 221k R6 221k R7 CH3 INPUTS 4 2 3 1 S - + G J3 1 2 J4 10k R5 20K R3 20K R4 6 5 7 - + U1:2 100 R10 1 3 2 J5:1 4 6 5 J5:2 POWER CONTROL INOUT 3 3 TO CONTROL 3 10uF C1 .1uF C2 .1uF C3 10 R1 10 R2 PC MET PC IN PC OUT .1uF C4 -15V2 7C 7C CH3 HTSNK FROM 2.21 R11 2.21 R12 GND 3 J1:1J1:2 J1:3J1:4 GP1 J2:1 J2:2J2:3 J2:4J2:5 0V 0V 0V RadioFans.CN 收音机爱 好者资料库 POWER AMPLIFIER MC303 2324 5 INPUT CH 3 750887 PCB RadioFans.CN 收音机爱 好者资料库 2526 6 CAPACITOR 750986 SCH J5J1:1 J1:2 J3:1 J3:2 J6 J4 J7 TO CH1 HTSNK + 75V - 75V 7A 7A 1 1 1 1 RED GRN YEL BLK TO CH2 HTSNK + 75V - 75V 7B 7B TO CH3 HTSNK + 75V - 75V 7C 7C J2:1 J2:2 27000uF C1 27000uF C3 27000uF C2 27000uF C4 PWR TRANSFORMER SECONDARY RED RED YEL 0.22uF BRIDGE RECTIFIER ! ! ! T4 RadioFans.CN 收音机爱 好者资料库 POWER AMPLIFIER MC303 2728 6 CAPACITOR 750986 PCB RadioFans.CN 收音机爱 好者资料库 2930 7 HEATSINK 750868/750881 SCH 1 of 2 8 8 9 9 (+) 8 8 (-) +15V PG AMP (-) SOURCE (-) SOURCE (+) AMP (+) AMP VOLTAGE VOLTAGE .15uF C1 .047uF C2 2 5W R1 4 R4 475 R19 DIFFERENTIAL 221 R37 100pF C18 CURRENT CURRENT 100pF C17 31 2 Q13 221 R36 DIFFERENTIAL 267k R39 324 R41 AMP 10uF C3 10uF C4 .1uF C6 FROM TERMINALFROM DISPLAY 499 R15 10k R6 221 R7 4.99k R8 200k R18 200k R21 475 R27 31 2 Q14 3 1 2 Q16 3 1 2 Q15 324 R40 31 2 Q3 0V 0V 0V - + U1:2 PG DETECTOR 21 3 S G D Q5 10M R23 .0068uF C7 47.5k R24 47.5k R26 221 R34 21 3 Q8 806 R31 21 3 S G D Q6 221 R33 2 1 3 Q17 3.32k R32 .1uF C5 100 R3 100 R2 31 2 Q4 2 1 3 Q10 21 3 Q12 3 2 1 Q18 3.32k R35 3 21 Q7 806 R30 267k R38 3 2 1 Q9 3 21 Q11 0V 0V 0V - + 84 B+ B- U1:1 B+B+ B-B- +14V -14V +14V -14V 8 OHM FB 2 OHM FB 22uF C13 475 R25 4.75k R22 220uF C9 475 R10 -15V 9 1pF C14 + DRV - DRV TO DISPLAY THERM 9 470 3 12 o +t RT1 OUTPUT METER 4/5 4/5 AMP GND FROM INPUT PG PG 9 METER METER 10uF C16 47 .5 W R29 -75VB- 47 .5W R28 10uF C15 +75VB+ MUTE 9 3.32k R5 22uF C8 365 R16 100pF C11 22pF C12 20K R17 6.49k .5% R20 10k R9 3 21 Q1 12 3 S G D Q2 +14V 267k R13 267k R14 10k R11 40.2k R12 10uF C10 -14V J4 100uF C30 267k R66 31 2 Q38 -14V D6 100k R67 +15V-15V +15V -15V4/5 4/5 TO INPUT +15V -15V 1 BLK AMP MUTING PG ATTENUATOR -18V -18V 0V J2:1 J2:4 J2:2 J2:3 J1:1 J1:2 J1:3 J1:4 J3:1 J3:2 J3:3 J3:4 J3:5 J3:6 -7V 6 5 7 1 2 3 RadioFans.CN 收音机爱 好者资料库 POWER AMPLIFIER MC303 3132 7 HEATSINK 750868/750881 SCH 2 of 2 6 (-) (+) 6 D2 + 75V LIM ITER CURRENT ADJUST J8:1 1 BIAS + - 75V J5:1 .22uF C19 .22uF C20 2.21 R42 2.21 R43 .01uF C21 365 R45 47uF C23 .01uF C22 31 2 Q19 D1 D4 22.1k R47 CURRENT D3 LIMITER 680 R48 BIAS .1uF C25 100pF C27 2 1 3 Q22 100pF C28 2 3 1 Q24 47 .5W R54 1.2V 2 3 Q23 3 2 1 Q25:1 3 2 1 Q30:1 3 2 1 Q29:1 3 2 1 Q34:1 J8:2 1.1k R64 1.1k R65 BIAS - FROM CAP J5:2 31 2 Q20 47uF C24 365 R44 680 R49 22.1k R46 D5 1.8k R53 1.8V 2 1 Q21 3 2 1 Q26:1 3 2 1 Q33:1 TO AUTOFRMR 54 Q34:2 1.5k R51 3 2 1 Q28:1 3 2 1 Q31:1 J6 100pF C26 54 Q33:2 1.8k R50 500 2 31 CCW R52 3 2 1 Q32:1 3 2 1 Q27:1 (+) OUTPUTS (+) DRIVER (-) DRIVER (-) OUTPUTS 54 Q31:2 54 Q32:2 .47x2 2 13 R55 31 2 Q37 .1uF C29 3 2 1 Q36:1 3 2 1 Q35:1 54 Q35:2 54 Q36:2 54 Q30:2 54 Q29:2 54 Q28:2 54 Q27:2 54 Q26:2 54 Q25:2 .47x2 2 1 3 R61 J7 1 WHT VIO .47x2 2 1 3 R57.47x2 2 13 R59 .47x2 2 13 R56.47x2 2 13 R58.47x2 2 1 3 R60 .47x2 2 1 3 R62 + DRV - DRV OUTPUT -75V +75V .47x2 2 1 3 R63 BIAS 3 1 .6V .6V .6V .6V .6V -.6V -.6V -.6V -.6V -.6V -1.2V -1.8V - BIAS ADJUSTMENT - ADJUST R52 FOR 19-23 mV DC ACROSS J8 WITH NO INPUT SIGNAL AND HEATSINKS COOL RadioFans.CN 收音机爱 好者资料库 3334 7 HEATSINK 750868/750881 PCB 129944 RadioFans.CN 收音机爱 好者资料库 POWER AMPLIFIER MC303 3536 8 TERMINAL 750890 SCH J1 J3 J2 J4 1 1 1 1 ORN RED BLU BLK FROM AUTOFORMER BP4 BP3 BP2 BP1 J5 J6:1 J6:4 7 7 TO HEATSINK 1 8 42COM RadioFans.CN 收音机爱 好者资料库 3738 8 TERMINAL 750890 PCB RadioFans.CN 收音机爱 好者资料库 POWER AMPLIFIER MC303 3940 9 DISPLAY 750869 SCH 1 of 2 1 1 ON 1 REM J4:1 J4:3 OFF J4:2 1 FP ON FP OFF GND 1 1 AUTO J7:1 OFF J7:3 1 ML OFF GND 182 R15 182 R16 182 R14 182 R13 182 R1 7 182 R1 8 POWER SWITCH METER SWITCH ILLUMINATION METER PG THERM METER CH3 METER PG THERM METER CH2 METER 7A PG FROM CH1 HTSNK THERM 7A J1:6 7A METER J1:5 CH1 METER J1:4 J2:6 J2:5 J2:4 J3:6 J3:5 J3:4 MUTE MUTE J1:1 TO CH1 HTSNK J1:2 MUTE J1:3 J2:1 J2:2 J2:3 J3:1 J3:2 J3:3 TO CH2 HTSNKTO CH3 HTSNK +15V -15V MUTE +15V -15V MUTE +15V -15V MUTE -15V +15V -15V +15V -15V +15V 7B 7B 7B 7C 7C 7C 2.21k R1 -15V +15V +5VBU FROM CH2 HTSNKFROM CH3 HTSNK 3 ILLUM 3 GNDJ5:9 J5:1 J5:4 J5:14 3 3 +15V -15V 3 +5VBU 3 MET LIGHTS J5:16 J5:7 J5:17 3 MUTE MUTE FROM CONTROL J5:10 J5:12FP ON FP OFF TO CONTROL 3 3 7A 7A 7A 7B 7B 7B 7C 7C 7C J6:4 +5VBU2 +5VBU J6:1 J6:12 2 GND 2 PW R RLY TO BACKUP FROM BACKUP J8:7 J8:5 J8:4 J8:18 33.2k R6 681 R7 31 2 Q5 CH1 POWER GUARD 4L 33.2k R4 681 R5 31 2 Q4 CH2 POWER GUARD 33.2k R2 681 R3 31 2 Q3 CH3 POWER GUARD J8:16 J8:13 J8:12 J8:15 J8:17 J8:14 J8:10 J8:2 33.2k R10 31 2 Q7 12.1k R11 31 2 Q6 2.21k R20 THERMAL PROTECTION 332 R8 12.1k R12 10k R9 31 2 Q8 -15V-15V-15V 12.1k R19 31 2 Q9 MUTE LOGO LED DS5 DS7 DS6 1k R27 806 R23 PW R SW LED MET SW LED DS1 4.75k R21 +5VBU POW ER LED +15V+15V 31 2 Q10 1.5k R2 2 10 10 10 10 10 10 10 10 10 10 10 10 +15V 31 2 Q2 +15V +15V 31 2 Q1 -15V J5:15 3 PW R RLY PWR RLY PWR RLY J6:2 J6:3 J6:5 J6:6 J6:7 J6:8 J6:9 J6:10 J6:11 J5:2 J5:3 J5:5 J5:6 J5:8 J5:18 J5:11 J5:13 5V 5V -18V 5V 0V 5V 0V 0V 0V 0V -15V.6V -14.4V -18V -18V -18V 5V 681 R60 GND GND GND MT1 LT MT2 LT MT3 LT PG3 LT PG2 LT PG1 LT PG COM PG COM PG COM SW2 SW1 0V 14V 14V 0V 0V 0V -9.8V 14.4V 14.4V 14.4V 1.2V 1.1V -.1V 0V .6V TO METER CONTROL RadioFans.CN 收音机爱 好者资料库 4142 9 DISPLAY 750869 SCH 2 of 2 20K R36 D1 221k R43 D10 D16 31 2 Q14 D2 .1uF C7 .47uF C10 221 R48 CH1 M ETER LOG AM P 10uF C4 150k R37 CH1 M ETER DRIVER D13 8 10 9 + - U2:3 31 2 Q11 31 2 Q17 +14V+14V 475k R51 D7 14 12 13 + - U2:4 20K R40 220uF C2 47.5 R33 2.21k R54 100k CCW 1 2 3 R57 +14V 1 1 MT1 |+| TO CH1 METER J13:2 J13:1