Bose FREESPACE BMA-125 Service Manual
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Bose FREESPACE BMA-125 Service Manual

Business music amplifier 120/230v
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SAFETY INFORMATION ................................................................................................................... 2
Electrostatic Discharge Sensitive (ESDS) ..................................................................................... 3
120V Version Specifications ........................................................................................................ 4-5
230V Version Specifications ........................................................................................................... 6
120V Disassembly/Assembly Procedures .................................................................................. 7-9
230V Disassembly/Assembly Procedures .............................................................................. 10-12
BMA-125 Test Procedures 120V .............................................................................................. 13-16
BMA 125 Test Procedures 230V .................................................................................................... 16
Part List Notes ................................................................................................................................ 17
120V Main Assembly Part List ...................................................................................................... 18
Figure 1. 120V Chassis Layout ...................................................................................................... 19
120V Amp PCB Part List ........................................................................................................... 20-22
120V Tone/Volume Control PCB Part List ............................................................................... 23-24
120V Equalizer PCB Part List ................................................................................................... 25-26
230V Main Assembly Part list .................................................................................................. 27-28
230V Amp PCB Part List ........................................................................................................... 29-31
230V Tone/Volume/Equalizer PCB Part List ............................................................................ 32-35
Input Module 2B37 Part List .......................................................................................................... 36
Input Module 2B50 Part List ..................................................................................................... 37-38
Figure 2. 2B37 Schematic and PCB Layout ................................................................................... 39
Figure 3. 2B50 Schematic and PCB Layout ................................................................................... 40
Figure 4. 120V Driver PCB Layout ................................................................................................. 41
Figure 5. 120V Tone/Volume Control PCB Layout ......................................................................... 41
Figure 6. 120V Equalizer PCB Layout (Solder Side) ..................................................................... 42
Figure 7. 120V Equalizer PCB Layout (Component Side) ............................................................. 42
Figure 8. 230V Driver PCB Layout ................................................................................................. 43
Figure 9. 230V Tone/Volume/Equalizer PCB Layout .................................................................... 44
Figure 10. and 11. 230V wiring diagram ................................................................................... 45-46

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  • Page 1: Table Of Contents

    Table of Contents SAFETY INFORMATION ........................2 Electrostatic Discharge Sensitive (ESDS) ..................3 120V Version Specifications ......................4-5 230V Version Specifications ......................6 120V Disassembly/Assembly Procedures .................. 7-9 230V Disassembly/Assembly Procedures ................10-12 BMA-125 Test Procedures 120V ....................13-16 BMA 125 Test Procedures 230V ....................16 Part List Notes ..........................

  • Page 2: Safety Information

    SAFETY INFORMATION 1. Parts that have special safety characteristics are identified by the symbol on schematics or by special notes on the parts list. Use only replacement parts that have critical characteristics recommended by the manufacturer. 2. Make leakage current or resistance measurements to determine that exposed parts are acceptably insulated from the supply circuit before returning the unit to the customer.

  • Page 3: Electrostatic Discharge Sensitive (Esds)

    ® BOSE CORPORATION WHICH IS BEING FURNISHED ONLY FOR THE PURPOSE OF SERVICING THE IDENTIFIED BOSE PRODUCT BY AN AUTHORIZED BOSE SERVICE CENTER OR OWNER OF THE BOSE PRODUCT, AND SHALL NOT BE REPRODUCED OR USED FOR ANY OTHER PURPOSE.

  • Page 4: 120V Version Specifications

    120V VERSION SPECIFICATIONS Power Output 125W Output Regulation Direct output: 0.5dB, no load to full load Transformer outputs: 1.5dB, no load to full load Input Sensitivity 2B37 dual input module Input 1: Microphones: 1KΩ/350µV Auxiliary: 10KΩ/100mV Input 2: Microphones: 1KΩ/350µV Auxiliary: 10KΩ/1V Input 3 &...
  • Page 5 120V VERSION SPECIFICATIONS (Continued) Mute >30dB (Mute Input 3, 4, 5) Control Interaction <1dB Power Outlet Unswitched AC Outlet 120VAC 60HZ, 500W AC Power 120VAC, 60HZ at 3.0A at rated output Consumption (0.15A at idle) Temperature Range 12° F to 140° F (-10° C to + 60° C) Output Protection Electronic foldback and thermal overload (both...

  • Page 6: 230V Version Specifications

    230V VERSION SPECIFICATIONS Power Output 125W Output Regulation Direct output: 0.5dB, no load to full load Transformer outputs: 1.5dB, no load to full load Input Sensitivity 2B37 dual input module Input 1: Microphones: 200Ω/400mV Input 2: Auxiliary: 10KΩ/1V Input 3 & 4: See instruction sheet enclosed with module Input 5: 10KΩ/100mV...

  • Page 7: 120V Disassembly/Assembly Procedures

    120V DISASSEMBLY/ASSEMBLY PROCEDURES 1. Top Cover Removal 5.3 Remove the three nuts that secure the input Five, bass and treble controls to the 1.1 Remove the ten screws that secure the chassis. top cover to the chassis. There are five on each side.
  • Page 8 120V DISASSEMBLY/ASSEMBLY PROCEDURES 11.2 Remove the two screws that secure 7.4 Remove all the wires from the pot. the equalizer to the chassis. Note: Make note of the wiring configura- tion. 11.3 Lift the equalizer PCB up. 8. Input 1, 2, 3, 4 and Master Volume 12.
  • Page 9 120V DISASSEMBLY/ASSEMBLY PROCEDURES 19. Output Transistor and Heat sink 15. Power Transformer Removal Replacement. 15.1 Remove the wires that connect to the 19.1 Push the transistor into the transistor AC outlet, power switch and driver PCB. socket. Note: Make note of the wiring configura- Note: Inspect the mylar insulator for tion.

  • Page 10: 230V Disassembly/Assembly Procedures

    230V DISASSEMBLY/ASSEMBLY PROCEDURES 5.3 Remove the two nuts that secure the 1. Top Cover Removal PCB shield to the chassis. 1.1 Remove the fourteen screws that 5.4 Slide the PCB towards the rear of the secure the top cover to the chassis. There unit until the potentiometer shafts clear the are seven on each side.
  • Page 11 230V DISASSEMBLY/ASSEMBLY PROCEDURES 8. Input 1, 2, 3, 4 and Master Volume 12. Speaker Output Transformer Replace- Control Replacement ment 8.1 Attach the wires to the pot. 12.1 Lower the transformer into the chas- sis so that the wires face toward the rear of 8.2 Insert the pot's shaft into the hole in the unit.
  • Page 12 230V DISASSEMBLY/ASSEMBLY PROCEDURES 15. Output Transistor and Heat Sink Removal 15.1 Remove the two nuts that secure the heat sinks to the chassis. 15.2 Lift the heat sink up. 15.3 Remove the two screws that secure the transistor to the heat sink. 15.4 With a pair of pliers, grab onto the transistor and pull it out of the transistor socket.

  • Page 13: Bma-125 Test Procedures 120V

    BMA-125 120V Test Procedures Ω 2. 4 Output Note: Remove the “4Ω” to “PRI” jumper. General Test Setup Connect a 4Ω load between “COM” and “4Ω”. Connect a 4Ω, 5Ω, 8Ω and 40Ω 200W load to the 4, 5, 8, and 40Ω outputs respectively. 2.1 Apply a 105Vrms, 1KHz signal to Input Five.
  • Page 14 BMA-125 120V Test Procedures 4.5 Adjust Input Five until 8.875 Vrms is Frequency Output Tolerence measured across the 8Ω load. Reference a (dB) (dB) dB meter to the output. 50Hz 1KHz 4.6 Measure the response according to the 20KHz -2.8 following table.
  • Page 15 BMA-125 120V Test Procedures 10.2 Reference a dB meter to the 4Ω 6.3 Measure the Tape Output. It should be output. 1Vrms ( -.21, +.26). 10.3 Short the two screws labeled mute 7. Mixer Output together. 7.1 Apply a 100mVrms, 1KHz signal to 10.4 Measure the 4Ω...

  • Page 16: Bma 125 Test Procedures 230V

    BMA-125 120V Test Procedures 12. Input 3, 4 Frequency Output (dB) Tolerence (dB) 12.1 Perform the test procedure 11, if the ±3 20Hz -18.4 optional input module is installed. ±1.5 85Hz 14.5 ±1.5 250Hz 13. MIC PAGE INPUT ±1.5 500Hz µ...

  • Page 17: Part List Notes

    PART LIST NOTES 1. This part is not normally available from Customer Service. Approval from the Field Service Manager is required before ordering. 2. The individual parts located on the PCB are listed in the electrical part list. This part is critical for safety purposes. Failure to use a substitute replacement with the same safety characteristics as the recommended replacement part might create shock, fire and/ or other hazards.

  • Page 18: 120V Main Assembly Part List

    120V Main Assembly Part List (Figure 1) Reference Description Part Number Qty S e e Designator Note Q101, 103 Transistor (MJ 15022) 185231 Q102, 104 Transistor (MJ 15023) 185232 S101-S104 Socket, transistor, W/TO-3CA 185310 S101-S104 Insulator, Wafer 183311 Power Transformer (T101) 185229 T101 Output Transformer (T102)
  • Page 19 Figure 1. 120V Chassis Layout...

  • Page 20: 120V Amp Pcb Part List

    120V AMP PCB Resistors Reference Description Part Number See Note Designator 5.1Ω, 5%, 1/4W, 185286 R2, 41 10KΩ, 5%, 1/4W, 185433 47KΩ, 5%, 1/4W, 185316 POT, 100KΩ, LIN 185317 FLAT PCB 51KΩ, 5%, 1/4W, 185318 750Ω, 5%, 1/4W, 185319 680Ω, 5%, 1/4W, 185320 470Ω, 5%, 5W 185321...
  • Page 21 120V AMP PCB Resistors (continued) Reference Description Part Number See Note Designator 100KΩ, 5%, 1/4W, 185427 200KΩ, 5%, 1/4W, 185339 82Ω, 5%, 1/4W, 185340 15KΩ, 5%, 1/4W, 185341 Capacitors Reference Description Part Number See Note Designator C2, 11 4.7 UF, 50V, 185342 ELCT NP C3, 4...
  • Page 22 120V AMP PCB Diodes Reference Description Part Number See Note Designator CR1, 2 ZENER, 5.1V, 185355 1/4W CR3-9, 16, 19-21 RECTIFIER 185356 CR10, 11 ZENER, 15V,1W 185357 6 AMP, 200V 185358 CR12-15 CR17 ZENER, 12.0V 185359 CR18 ZENER, 22.0V 185360 Transistors Reference Description...

  • Page 23: 120V Tone/Volume Control Pcb Part List

    120V Tone/Volume Control PCB Resistors Reference Description Part Number See Note Designator R2, 3, 4, 5, 7, 26, 1.2KΩ, 5%, 1/4W, 185393 27, 28, 30 47KΩ, 5%, 1/4W, 185316 R8, 39 100Ω, 5%, 1/4W 185429 R9, 10, 13, 16 1.0KΩ, 5%, 1/4W, 185442 R11, 40 1OKΩ, 5%, 1/4W,...
  • Page 24 120V Tone/Volume Control PCB Capacitors (continued) Reference Description Part Number See Note Designator 56 PF, 50V, CER, 185420 47 µF, 10V, ELCT, C8,9 185421 10V, 680 µFD 185412 .015 µF, 50V, C13,14 185413 CER, 20% 220 PF, 50V, 185414 CER, 20% 22 PF, 1KV, CER, 185415 .01 µF, 50V, CER,...

  • Page 25: 120V Equalizer Pcb Part List

    120V Equalizer PCB Resistors Reference Description Part Number Reference Designator R1, 2, 4, 5, 16, 18 10.0KΩ, 1/4W, 1% 185524 22.1KΩ, 1/4, 1% 185546 R6, 7, 9, 14, 20, 4.75KΩ, 1/4W, 1% 185560 22, 28 93.1KΩ, 1/4, 1% 185541 R10, 23 25.5KΩ, 1/4W, 1% 185522 R11, 24...
  • Page 26 120V Equalizer PCB Miscellaneous Reference Description Part Number Reference Designator 12 PIN, FRICTION 185361 WIRE, SOL BARE, 185391 TND 22 A U1-4 SOCKET, 8 PIN 185392...

  • Page 27: 230V Main Assembly Part List

    230V Main Assembly Part List (Figure 10, 11) Reference Description Part S e e Designator Number Note Q101, 102 Transistor, MJ 15022 185231 Q103, 104 Transistor, MJ 15023 185232 T102 Transformer, Output 185279 T101 Transformer, Power 185280 R107, 108 510Ω, 5%, 1/4W CF 185281 R109 1Ω, 5%, 1/2W CF...
  • Page 28 230V Main Assembly Part List (continued) (Figure 2, 3) Reference Description Part S e e Designator Number Note Power Cord, EUR 185314 Power Cord, U.K. 185283 Power Cord, AUS 185286 2B50 Dual input module-Mic 180139-2B50 (screws)/Stereo summing input (AUX) 2B37 Dual input module-Mic 180140-2B37 (Screws)/Stereo...

  • Page 29: 230V Amp Pcb Part List

    230V AMP PCB Resistors Reference Description Part Number See Note Designator 51KΩ, 5%, 1/4W, 185425 R2, 45 5.1KΩ, 5%, 1/4W, 185426 R3, 36 100KΩ, 5%, 1/4W, 185427 30Ω, 5%, 1/4W, 185428 R5, 18, 21, 24, 25, 100Ω, 5%, 1/4W, 185429 40, 41 16KΩ, 5%, 1/4W, 185430...
  • Page 30 230V AMP PCB Transistors Reference Description Part Number See Note Designator MPS-A93 185465 2N5551 185466 Q3, 6 MJE340 185467 Q4, 5 MJE350 185468 Q7, 16 2N5088 185469 Q8, 15 2N5086 185470 2N3904 185471 Q10, 11 2N3906 185472 Q12, 13 2N5210 185473 Integrated Circuits Reference...
  • Page 31 230V AMP PCB Miscellaneous Reference Description Part Number See Note Designator SPDT, 24V COIL 185483 4 PIN FRICTION 185484 LOCK MOLEX, 6 PIN 185485 MOLEX, 5 PIN 185486 (U2, 3) HEATSINK W/ 185487 LEGS (Q5, Q6) BRKT, HTSNK 185488 (Q5, Q6, U2, U3) LK WASH, 4 185489 SPLT SPRING...

  • Page 32: 230V Tone/Volume/Equalizer Pcb Part List

    230V Tone/Volume/Equalizer PCB Resistors Reference Description Part Number See Note Designator R1, 2, 5, 6, 8 5.6KΩ, 5%, 1/4W, 185492 R3, 4, 14, 16, 18 4.7KΩ, 5%, 1/4W, 185493 POT, 5KΩ, PCB 185494 7.5KΩ, 5%, 1/4W, 185495 R10,11 1KΩ, 5%, 1/4W, 185442 R12, 13, 20 105KΩ, 1%, 1/4W...
  • Page 33 230V Tone/Volume/Equalizer PCB Resistors Reference Description Part Number See Note Designator 3.09KΩ, 1%, 185516 1/4W, MF 825KΩ, 1%, 1/4W, 185517 82.5KΩ, 1%, 185518 1/4W, MF R52, 54 8.25KΩ, 1%, 185519 1/4W, MF 7150Ω, 1/4W 185520 Capacitors Reference Description Part Number See Note Designator 4.7 µF, 50V, ELCT...
  • Page 34 230V Tone/Volume/Equalizer PCB Capacitors Reference Description Part Number See Note Designator .1 µF C37, 38 185537 .0068 µF 185538 330 PF, 5%, CER 185539 3900 PF, 50V, 185540 CER, 20% 100 PF, 50V, CER 185453 Transistors Reference Description Part Number See Note Designator 2N5086...
  • Page 35 230V Tone/Volume/Equalizer PCB Miscellaneous Reference Description Part Number See Note Designator 12 PIN FRICTION 185548 LOCK 3 PIN, 1 RT ANG 185549 9 PIN 185550 FRICTION LK 185551 6 PIN FRICTION 185552 8 PIN 185553 FRICTION LK 185484 3 PIN FRICTION 185555 U1, 2, 4, 5 SOCKET, 8 PIN...

  • Page 36: Input Module 2B37 Part List

    Input Module 2B37 Part List Resistors Reference Description Part Number See Note Designator R1, 10 56KΩ, 1/4W, 5% 185394 R2, 11 24KΩ, 1/4W, 5% 185405 R3, 12 820Ω, 1/4W, 5% 185422 R4, 15 10KΩ, 1/4W, 5% 185433 R5, 7, 13, 14 20KΩ, 1/4W, 5% 185402 1.8KΩ, 1/4W, 5%...

  • Page 37: Input Module 2B50 Part List

    Input Module 2B50 Part List Resistors Reference Description Part Number See Note Designator R1, 2, 11, 15 5.6KΩ, 1/4W, 5% 185492 R3, 6, 7 604Ω, 1/4W, 1% 185559 R4, 5 100Ω, 1/4W, 5% 185429 68Ω, 1/4W, 5% 185571 R9, 14 51KΩ, 1/4W, 5% 185425 5100, 1/4W, 5%...
  • Page 38 Input Module 2B50 Part List (continued) Miscellaneous Reference Description Part Number See Note Designator 3 PIN 185555 2 PIN 185558 5 PIN 185551 J3, 4 185301 U1, 2 IC SOCKET, 8 185556...
  • Page 39 Figure 2. 2B37 Schematic and PCB Layout...
  • Page 40 Figure 3. 2B50 Schematic and PCB Layout...
  • Page 41 Figure 4. 120V Driver PCB Layout Figure 5. 120V Tone/Volume Control PCB Layout...
  • Page 42 Figure 6. 120V Equalizer PCB Layout (Solder Side) Figure 7. 120V Equalizer PCB Layout (Component Side)
  • Page 43 Figure 8. 230V Driver PCB Layout...
  • Page 44 Figure 9. 230V Tone/Volume/Equalizer PCB Layout...
  • Page 45 Figure 10. 230V Wiring Diagram (Part 1)
  • Page 46 Figure 11. 230V Wiring Diagram (Part 2)
  • Page 48 SPECIFICATIONS AND FEATURES SUBJECT TO CHANGE WITHOUT NOTICE ® ® BOSE CORPORATION THE MOUNTAIN FRAMINGHAM, MASSACHUSETTS USA 01701 P/N 177864 3/96: REV. 0 FOR TECHNICAL ASSISTANCE OR PART ORDERS, CALL 1 -800 -367 -4008...
  • Page 49 ® ® FREESPACE BUSINESS MUSIC AMPLIFIER BMA-125 120/230V 120V Version shown Service Manual ©1996 Bose Corporation Part Number 177864...

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