Ampeg pb 250a portabass preamp schematic

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D C B A 4 3 2 NOTES:THIS SCHEMATIC IS PROVIDED FOR USE BY QUALIFIED PERSONNEL. CAUTION: TO AVOID RISK OF ELECTRIC SHOCK, REFER SERVICING TO QUALIFIED THIS UNIT CONTAINS HAZARDOUS VOLTAGE. DISCONNECT POWER AND BE SURE POWER SUPPLY IS DISCHARGED BEFORE TOUCHING INTERNAL PARTS. 1) CAUTION: SHOCK HAZARD!! 2) UNLESS NOTED, RESISTOR VALUES IN OHMS, 1/4W-5% TOL. CAPACITOR VALUES IN MICROFARADS, 50V-10% TOL. 3) VOLTAGES ARE MEASURED WITH 1 MEGOHM OSCILLOSCOPE AND 10 MEGOHM DIGITAL VOLTMETER. SERVICE PERSONNEL. DO NOT PERFORM ANY SERVICING BEYOND THAT EXPLAINED IN THE OPERATING INSTRUCTIONS. D C B A 1 F E 1 Signatures: Checked:Drawn: SheetClass Code: THE INFORMATION CONTAINED ON THIS DRAWING IS PROPRIETARY TO Drawing Size: Drawing Type: Schematic Released:REV Date DESCRIPTION E Tolerance: Plot Date:Plot Time: Thu Jul 25, 2002 0 7-22-02 2 RLB R36 WAS 820 OHMS; Q1 WAS MPS-A13 1 7-25-02 CONTROL ISSUE N00910 C ofDrawing Title: Drawing Number:NONE 2Ecr(s)/Ecn(s) First Used On: ST. LOUIS MUSIC, INC Date: 8-21-01 11880 Borman Drive, St. Louis, MO 63146 Chgd By Appvd by FPB250a 07S592-XX 2 BASS PREAMP Date 4 3 D C B A 4 3 2 NOTES:THIS SCHEMATIC IS PROVIDED FOR USE BY QUALIFIED PERSONNEL. CAUTION: TO AVOID RISK OF ELECTRIC SHOCK, REFER SERVICING TO QUALIFIED THIS UNIT CONTAINS HAZARDOUS VOLTAGE. DISCONNECT POWER AND BE SURE POWER SUPPLY IS DISCHARGED BEFORE TOUCHING INTERNAL PARTS. 1) CAUTION: SHOCK HAZARD!! 2) UNLESS NOTED, RESISTOR VALUES IN OHMS, 1/4W-5% TOL. CAPACITOR VALUES IN MICROFARADS, 50V-10% TOL. 3) VOLTAGES ARE MEASURED WITH 1 MEGOHM OSCILLOSCOPE AND 10 MEGOHM DIGITAL VOLTMETER. SERVICE PERSONNEL. DO NOT PERFORM ANY SERVICING BEYOND THAT EXPLAINED IN THE OPERATING INSTRUCTIONS. D C B A 1 F E 1 Signatures: Checked:Drawn: SheetClass Code: THE INFORMATION CONTAINED ON THIS DRAWING IS PROPRIETARY TO Drawing Size: Drawing Type: Schematic Released:REV Date DESCRIPTION E Tolerance: Plot Date:Plot Time: Thu Jul 25, 2002 0 7-22-02 2 RLB R36 WAS 820 OHMS; Q1 WAS MPS-A13 1 7-25-02 CONTROL ISSUE N00910 C ofDrawing Title: Drawing Number:NONE 2Ecr(s)/Ecn(s) First Used On: ST. LOUIS MUSIC, INC Date: 8-21-01 11880 Borman Drive, St. Louis, MO 63146 Chgd By Appvd by FPB250a 07S592-XX 2 BASS PREAMP Date 4 3 4 CWP6 50K L 2.2KR46 CW100K AP7 R55 YELD10 220KR58 C31 50V 2.2 uF R492.2K 2.2KR51 1N914D975V PIV R6047K .1 50VC36 2.2KR44 2.2KR59 23 1 U5:A TLO-72 100KR57 R541K G S DQ4 R64 47K 1234567891011 J3 1234567 J4 R531K R50100K R432.2K 1C3350V 1N914D875V PIV 220KR61 10C34100V 50V.1C37 .1 50VC38 R4847K R521K 65 7 U6:B TLO-72 C30 50V 2.2 uF R472.2K R56 2N5210Q5 23 1 TLO-72 U6:A