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AUSTRALIAN MONITOR AMC+250, Installation And Operation Manual, Page: 36 / 36

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AUSTRALIAN MONITOR AMC+250 Installation And Operation Manual Download Page 36

Australian Monitor

 Service Bulletin 

AMC+250 Mixer Amplifier 

AMC+250P Booster Amplifier

 

9 March 2012 

 

 

 

Page 1 of 1 

 

Applicable Models 

This bulletin applies to AMC+250 and AMC+250P models manufactured prior to March 2012. 

 

For Information Only 

 

This bulletin is intended for service technicians only and is to be applied when replacing failed bridge rectifiers. 

This bulletin does not apply to functional units. 

 

Known Issue 

A small number of bridge rectifier failures at power on have been observed. 

 

Details 

It is believed that RoHS compliant 35A bridge rectifiers are not as reliable as the earlier non-RoHS equivalents. 

We have decided to increase the rating from 35A to 50A to provide additional headroom under turn on conditions.  

 

Solution 

When replacing a failed bridge rectifier (BR1), substitute the original 35A bridge with a 50A model as indicated in 
the table below. 

 

 

 

Model 

VRRM 

I(AV) 

Terminals 

 

Original Part 

KBPC3510 

1000V 

35A 

0.25" FASTON terminals 

 

Replacement Part 

KBPC5010 

1000V 

50A 

0.25" FASTON terminals 

 

 

Notes 

 

All models manufactured March 2012 or later are fitted with the 50A replacement part. 

 

Summary of Contents for AMC+250

Page 1: ...ilverwater NSW 2128 Australia 61 2 9647 1411 www australianmonitor com au SERVICE INFORMATION AMC 250 MIXER AMPLIFIER CONTENTS OPERATION MANUAL SCHEMATIC DIAGRAMS COMPONENT OVERLAYS TEST PROCEDURE REPLACEMENT PARTS LIST SERVICE BULLETINS ...

Page 2: ...AMC SERIES 30W 60W 120W 250W MIXER AMPLIFIERS INSTALLATION AND OPERATION MANUAL ...

Page 3: ...fan intake or exhaust ports Do not operate equipment on a surface or in an environment which may impede the normal flow of air around the unit such as a bed rug weathersheet carpet or completely enclosed rack If the unit is used in an extremely dusty or smoky environment the unit should be periodically blown free of foreign matter 14 Do not remove the cover Removing the cover will expose you to po...

Page 4: ...Rev B 6th Jun 2006 Rev C 26th May 2008 This symbol is intended to alert the user to the presence of uninsulated dangerous voltage within the products enclosure that may be of sufficient magnitude to constitute a risk of electric shock to persons This symbol is intended to alert the user to the presence of important operational and maintenance servicing instructions in the literature accompanying t...

Page 5: ...each channel input 2 Bass There is 12dB of cut and boost at 100Hz 3 Treble There is 9dB of cut and boost at 10kHz 4 Master This controls the overall mixed output level 5 On This LED indicates the unit is powered on 6 Power This switch switches power on or off the mains The up position is on 5 6 2 3 4 1 ...

Page 6: ... available on 115V models 100V out is available on 230V 240V models Note Only connect one output either Distributed Line or Low Impedance per channel Do not connect LowZ and 70 100V at the same time The output strip comes fitted with a touch proof cover held in place by two M3 machine screws with flat and spring washers 5 IEC Mains Input Socket This is a standard IEC 3 pin socket It accepts a stan...

Page 7: ... 0 75mm2 AWG16 1 5mm2 AWG13 2 5mm2 70V Up to 50m AWG26 0 12mm2 AWG24 0 2mm2 AWG22 0 35mm2 AWG18 0 75mm2 50m 200m AWG20 0 5mm2 AWG18 0 75mm2 AWG16 1 5mm2 AWG13 2 5mm2 Over 200m AWG18 0 75mm2 AWG16 1 5mm2 AWG13 2 5mm2 AWG10 6 0mm2 4 ohm Up to 10m AWG18 0 75mm2 AWG18 0 75mm2 AWG18 0 75mm2 AWG18 0 75mm2 10m 30m AWG13 2 5mm2 AWG13 2 5mm2 AWG13 2 5mm2 AWG13 0 35mm2 Over 30m Not Recommended Not Recommend...

Page 8: ... at source Reduce volume levels on front panel Reduce Bass control level No sound but amp is on Volume controls down Amplifier has overheated AMC 60 AMC 120 AMC 250 only DC fuse s blown Check volume controls Check for obstructions above and below Make sure the amplifier is well ventilated Refer product to local Australian Monitor dealer No sound from channels 2 and 3 Priority function is being use...

Page 9: ...nts PRIORITY Channel 1 will mute channels 2 3 and 4 This will only occur when signal appears on channel 1 irrespective of the channel volume control Priority can be disabled See below The release time is approx 3 secs and is NOT adjustable The mute depth is approx 40dB and is not adjustable ...

Page 10: ...PAGE 9 AMC SERIES INSTALLATION AND OPERATION MANUAL dimensions ...

Page 11: ...16 5lb 23 1lb 27 6lb 30 8lb SHIPPING DIMENSIONS WXHXD 510 x 145 x 297mm 525 x 175 x 385mm 525 x 175 x 385mm 525 x 185 x 470mm 20 1 x 5 7 x 11 7 20 7 x 6 9 x 15 2 20 7 x 6 9 x 15 2 20 7 x 7 3 x 18 5 MAINS CURRENT DRAW 240V FULL POWER 0 35A 0 66A 1 20A 2 53A 1 3 POWER 0 23A 0 44A 0 80A 1 61A 1 8 POWER 0 17A 0 32A 0 55A 1 10 IDLE 0 08A 0 13A 0 15A 0 15A MAINS CURRENT DRAW 115V FULL POWER 0 73A 1 38A ...

Page 12: ...n 0 5 MIC INPUT SENSITIVITY 1mV 200ohm IMPEDANCE 1k3 ohm HEADROOM 77mV 37dB AUX INPUT SENSITIVITY 0 5V 100kohm IMPEDANCE 200kohm HEADROOM 15V 30dB TONE CONTROL BASS 100HZ 12 dB TREBLE 10KHZ 9 dB LINE OUT NOMINAL OUTPUT 0 775V 1kohm OUTPUT IMPEDANCE 100ohm REC OUT NOMINAL OUTPUT 250mV 10kohm OUTPUT IMPEDANCE 1kohm ...

Page 13: ... 31 Walsh Street Thebarton SA 5031 PO Box 157 Hindmarsh SA 5007 Phone 08 8352 4444 Fax 08 8352 4488 Email sa audiotelex com au PERTH WA SALES 3 11 Howe Street Osborne Park WA 6017 PO Box 1281 Osborne Park BC WA 6916 Phone 08 9204 0200 Fax 08 9244 3783 Email wa audiotelex com au AUCKLAND NZ SALES 9C Piermark Drive Albany 0752 New Zealand PO Box 300 512 Albany 0752 Phone 09 415 9426 Fax 09 415 9864 ...

Page 14: ...R22 1K BIAS R23 0E R26 0E D2 1N4007 D1 1N4007 T5 BC639 T6 BC639 R28 47R R27 68R R29 47R R30 68R C5A 6800u 63V R39 150E 5W X 2 L 10V L 230V F2 2A HRC VC Mains 240 V R36 0 39E 5W T12 TIP35C R35 0 39E 5W T11 TIP35C PRIM1 T16 BD139 R40 2K2 C13 47 50 C14 47 50 D7 24V Com 4Ohm Com 100V 1 2 3 4 5 6 CN1 CON6 VCC TH1 THERMISTOR 10K C17 1n C16 1n C8 NC C7 NC 24V C9 NC C10 NC R46 47K R50 2k2 6 5 7 8 IC5B 145...

Page 15: ...n by balanced signal 1K R21 1K R22 BIAS AMC 250 AMP 02 0E R23 0E R26 D2 1N4007 D1 1N4007 T5 BC639 T6 BC639 33R R28 68R R27 39R R29 68R R30 C5A 6800u 63V 150E 5W X 2 R39 L2 115V L1 115V F2 230V T4A 115V T8A HRC VC 230V 115VAC 0 39E 5W R36 T12 TIP35C 0 39E 5W R35 T11 TIP35C PRIM1 T16 BD139 R40 2K2 C13 47 50 C14 47 50 D7 24V Com 4Ohm Com 100V 1 2 3 4 5 6 CN1 CON6 VCC TH1 THERMISTOR 10K C17 1n C16 1n ...

Page 16: ...VCC Signal Signal 220E R27 TO AMP TO AMP C4 4 7u C14 4 7U R23 10K R24 10K C19 47 25V VCC VCC 1 2 3 4 5 6 7 8 9 10 CN1 TH TH IN IN TH TH VCC IN IN 1 2VCC R33 4k7 R29 10K R30 2K2 GND 12V R31 220E 2W C21 1000 25 1 2 3 4 5 6 CN2 R32 1K5 CN3 LED1 1 2 3 PRIORITY VCC VCC VCC C17 10 25 T2 C1815 2 3 1 4 IC3A LM833 6 5 7 8 IC3B LM833 2 3 1 4 IC4A LM358 6 5 7 8 IC4B LM358 6 5 7 8 IC1B LM833 2 3 1 4 IC1A LM83...

Page 17: ...6 470p R20 1K R21 1K C22 4u7 C21 4u7 C25 4u7 C17 10 25 NP C18 10 25 NP C16 10 25 NP 1 2 3 4 7 6 5 7 6 5 8 8 VCC AG 1 2 VCC TAPE OUT GRD CH 1 OUT CH 2 OUT CH 3 OUT TAPE OUT LINE OUT MIX OUT MIX OUT 1 2 3 4 5 6 7 8 9 10 CN1 CON10 VCC VCC VCC G L R RCA1A RCA 4POLE G L R RCA1B RCA 4POLE G L R RCA2A RCA 4POLE 3 2 1 XLR1 XLR FEMALE 3 2 1 XLR2 XLR FEMALE 3 2 1 XLR3 XLR FEMALE 3 2 1 XLR5 XLR MALE C24 10 2...

Page 18: ...43 R41 R42 J7 J9 J8 J13 J12 R22 R32 J1 R23 R31 R21 J11 J5 R24 R27 D2 D1 T15 T6 T5 T2 T1 T4 T3 F1 R12 C3 C4 R45 R10 R44 R3 R4 R8 R11 R13 R20 R17 R15 TH1 T11 T9 T12 T15 T16 R33 R39 R40 J10 R30 T1 PR1 T8 R26 J3 R40 T16 D7 C14 C13 J18 R2 J17 J2 R25 F2 R35 C5A QC1 O P PRIMARY QC2 O P PRIMARY A17 T10 T14 T13 T18 T20 R38 R36 R34 R51 QC3 BRIDGE VE QC5 OP CT2 QC6 BRIDGE GND QC4 OP CT1 J14 J15 J6 J16 C5B CN...

Page 19: ...R3 VR2 T4 T3 T1 R47 R46 R40 R39 R38 R37 R36 R34 R33 R32 R31 R30 R29 R28 R27 R26 R25 R24 R23 R21 R19 R18 R17 R16 R15 R13 R12 R11 R10 R8 R7 R6 R5 R4 R3 R2 R1 PRIORITY IC4 IC1 D6 CN3 D4 D3 D2 D1 CN2 CN1 C20 C19 C17 C16 C15 C14 C13 C12 C11 C10 C9 C8 C7 C4 C3 C1 R20 R22 C21 IC3 T2 C2 T6 R14 R9 J16 J15 J13 J12 J10 J10 J9 J8 J7 J7 J6 J5 J4 J3 J3 J2 J1 J14 J17 ...

Page 20: ...R25 R27 R21 R24 R23 C29 RCA3 J2 J1 XLR4 C25 R22 R21 XLR1 XLR2 XLR3 RCA2 C21 C22 C11 C20 C19 C24 C23 C9 C17 C16 C13 C10 C8 C18 C15 C14 C12 C7 C5 C6 C3 C1 C2 R19 R20 R16 R13 R17 R9 R12 R10 R7 R11 R8 R14 R6 R5 R15 R4 R3 R2 R1 IC2 IC1 R18 C4 S1 R28 R29 R30 R31 R32 R33 R34 R35 J4 J5 J6 C32 AMC input E A59 ...

Page 21: ...Power up 3 1 Voltages 3 2 Bias setup 4 Initial AC Checks 4 1 Signal check and gain of amp 4 2 Emitter current check 4 3 Inputs 4 4 Outputs 4 5 Phantom power 5 THD 6 Sensitivity 6 1 Mic inputs 6 2 AUX inputs 7 Bandwidth 8 Bass Treble 9 Phase 10 Priority check 11 Current Limit 12 Noise floor SNR 13 Fan Thermal check 14 Final check for damage 15 Factory setting 16 Listening Test 16 1 Switch on thump ...

Page 22: ... check 2 x AC fuses 3 15A 20x5mm 2 x DC fuses 10A 20x5mm 2 2 Connections Connect amplifier to Variac 0Vac Signal generator mic1 no signal Resistive load 4ohm on 4ohm terminal with meters oscilloscope 2 3 Reset controls All volume controls to minimum Bass treble control to centre Phantom power switch to off PR1 preset on the amplifier PCB CCW 3 Power up Turn on power switch and adjust voltage to 23...

Page 23: ...VAC 2VAC 4 2 Emitter current check Setup Signal generator 1mVAC 1kHz Ch1 pot max CW Ch2 4 pot min CCW Bass Treble centre Master pot max CCW Output metering 4ohm out Load 4ohm Procedure Set output to 22VAC using master volume control Check voltage across emitter resistors of power devices P F Voltage shall be between 300mVDC 400mVDC Setup for next test Reset Ch1 volume pot to min Set master volume ...

Page 24: ... between pins 2 and 3 Setup for next test Remove input signal 4 5 Phantom power Setup Signal in none Channel pot max CW Bass Treble centre Master pot max CW Output metering 4ohm output terminals Load 4ohm Procedure Set phantom switch to on Measure the DC voltage on Ch1 XLR input pins 2 and 3 ref to pin 1 P F The reading shall be 12 0VDC 1 0VDC Using the phantom power LED jig connect to XLR in Set ...

Page 25: ...HD P F Reading shall be 0 5 Values to be recorded Value Pass Range 5 THD 0 0 5 6 Sensitivity 6 1 Mic inputs Setup Signal generator 1mVAC 1kHz Signal in Ch1 XLR Ch1 pot somewhere Ch2 4 pots min CCW Bass Treble centre Master pot max CW Output metering 100Vout Load 40ohm Procedure Set channel pot to max P F The output reading shall be 100VAC 5VAC Repeat for all channels Setup for next test Move the s...

Page 26: ...between 20Hz 30Hz Adjust the frequency on the signal generator up till the output is 50VAC P F The frequency shall be between 20kHz 40kHz Values to be recorded Value Pass Range 7a Bandwidth low 20Hz 30Hz 7b Bandwidth high 20kHz 40kHz Setup for next test Set the frequency back to 1kHz 8 Bass Treble Setup Signal generator 0 5VAC 1kHz Signal in Ch4 RCA Ch1 3 pot max CW Ch4 pot somewhere Bass Treble c...

Page 27: ... the low impedance outputs and the line outputs P F The signals on the CRO shall be in phase for all outputs 100V 4ohm 10 Priority check Setup Signal generator 0 5VAC 1kHz Signal in Ch4 RCA Ch pots max CW Bass Treble centre Master pot max CW Output metering 100Vout Load 40ohm Procedure Plug a microphone into input 1 and oscillator to input 4 Turn channel 1 pot to min CCW Speak into the microphone ...

Page 28: ...t Change the load back to 80ohm Set all volume pots to centre Remove the signal from Ch4 12 Noise floor SNR Setup Signal in none Ch pots centre Bass Treble centre Master pot centre Output metering 100Vout Load 40ohm Procedure Put dummy lid on Check for Hum Noise P F The output shall be reading 6mVAC 85dBr ref 100V Values to be recorded Value Pass Range 12 Noise floor 0mV 6mV Set Ch1 volume to max ...

Page 29: ...recorded Value Pass Range 13a Fan turn on 50degC 70degC 13b Thermal cutout 90degC 105degC 14 Final check for damage Disconnect from test bench and inspect for scratches on external paint 15 Factory setting Set up the unit for default factory setting as below Links a VOX Muting Enable Pot positions a Channel volume min b Master volume min c Bass Treble centre Attach tested sticker ...

Page 30: ...hump Switch on the set and check for any ON Thump Ensure unit does not thump Check that no low frequencies are audible Make all channel pots minimum 16 2 Audio quality Check CD Player AUX output for all channels and tone control for all channels 16 3 Priority Check Priority function CH 1 over CH 2 3 4 16 4 Current Limit Short the output with signal ON Signal should mute and return back ...

Page 31: ...eft 200mVAC 300mVAC Tape output right 200mVAC 300mVAC Line output 0 65VAC 0 80VAC 4 5 Phantom power P F The reading shall be 12 0VDC 1 0VDC P F The LED shall be off P F The LED shall be on 5 THD P F Reading shall be 0 5 6 Sensitivity 6 1 Mic inputs P F The output reading shall be 100VAC 5VAC 6 2 AUX inputs P F The output readings shall be 100VAC 5VAC 7 Bandwidth P F The frequency shall be between ...

Page 32: ...aking 11 Current Limit P F The mains current shall be 3 5Aac P F The output shall be reading 30VAC 1V 12 Noise floor SNR P F The output shall be reading 6mVAC 85dBr ref 100V 13 Fan Thermal check P F the fan shall switch on between 50degC 70degC P F The output shall mute to 10V at a temp between 90 105degC ...

Page 33: ...50OPB BR025001 Transformers AMC 30 mains transformer AMC 30TX BR030123 AMC 30 output transformer AMC 30OT BR030124 AMC 60 mains transformer AMC 60TX BD6041 AMC 60 output transformer AMC 60OT BD060127 AMC 120 mains transformer AMC 120PTX BD0642 AMC 120 drive transformer BR0120036 BR0120036 AMC 120 output transformer AMC 120OT BR0120125 AMC 250 mains transformer AMC 250TX BR0250140 AMC 250 output tr...

Page 34: ...of a rating that is too low for use in areas that encounter elevated mains voltages Solution The problem can easily be rectified by placing the existing mains fuse as follows 115V Operation T8A 250V slow blow ceramic HRC type M205 fuse 20 x 5mm 230V Operation T4A 250V slow blow ceramic HRC type M205 fuse 20 x 5mm Procedure 1 Remove the mains lead from the amplifier 2 Remove the fuse holder drawer ...

Page 35: ...ing the existing mains fuse with name brand quality fuses available from Element14 as follows 115V Operation North America 230V Operation Australia Europe Model Fuse Rating Element14 Fuse Rating Element 14 AMC 30 T1A 1123115 T500mA 1123121 AMC 60 T3 15A 1123119 T1 6A 1123113 AMC 120 AMC 120P T4A 1123120 T2A 1123118 AMC 250 AMC 250P AMC 1202P T8A 1123125 T4A 1123120 All fuses are Cooper Bussman 250...

Page 36: ...ifier failures at power on have been observed Details It is believed that RoHS compliant 35A bridge rectifiers are not as reliable as the earlier non RoHS equivalents We have decided to increase the rating from 35A to 50A to provide additional headroom under turn on conditions Solution When replacing a failed bridge rectifier BR1 substitute the original 35A bridge with a 50A model as indicated in ...

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