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Summary of Contents for MARCO-TECH 5000VZ

Page 1: ...outputs Additional protectionfeatures include input current sense overvoltage AC mains A mode of protection which may be switched on or off is called Loudspeaker Offset Integration LOI The LOI circui...

Page 2: ...iques This produces ideal behavior and results n ultra low distortion val es Aluminum extrusions have been widely used for heatsinks in power amplifiers due to their low cost and reasonable performanc...

Page 3: ...side aswellasthe high side bystealing low side bias and drive Taking that a step further any protective action which limits mutes or shuts down the amplifier will accomplish the same thing by stealin...

Page 4: ...sely set bias voltage Bias voltage is easily measured from pin 2 hot to pin 4 of ATE ports TP1 and TP2 Refer to section 2 for appropriate test procedures Q504 stheHSNPNpre driverandQ511 istheHSNPNdriv...

Page 5: ...ngfix LSbias voltageas measured from pin 15 hot topin13ofapplicableATEportTP1 orTP2 Potentiometer R556 adjusts bias in the LS Diodes D504 and D505 control polarity of applied LS drive signal Via the b...

Page 6: ...nverting the signal Low Side Bias portion on positive output module and differential circuit which clamps Low Side signal nthe event of ODER or other protective function VCC1 VCC1 VCC1 Q527 I L t H534...

Page 7: ...rticulated power supply technology It enables Crown to pack tremendous power into just 5 25 inches of vertical rack space A power supply must be large enoughto handlethe m ximum voltage and current ne...

Page 8: ...y is divided into two par s Whenthe voltagerequirements are not high it op rales in a parallel mode to produce less vollage and more current The power transistors slay cooler and are nol torced lo nee...

Page 9: ...ridge 1 In both examples it can be seen that when the MOSFET switch is off the dual supplies are torced to op rate na parallel mode Audio level is sensed via a line tapping off the NFb loop Whenaudio...

Page 10: ...r than ODEP limiting this may be a worse condition for speakers Seldom will the amplifier be operated locked in high current mode unless a very low impedance is being driven By the same token it s als...

Page 11: ...empted The output of a 555 timer U703 on the control module determines whether the MOSFETs are switched on high or off low This 555 device and the various sources that feed the 555 are the things that...

Page 12: ...the safe operating area of the output stage Thermal sensors give the ODER circuitry vital Information on the operating temperature of the heat sinks on whichthe output devices are mounted This tempera...

Page 13: ...the safe operating area of the output stage Thermal sensors give the ODEP circuitry vital nformation on the operating temperatureof the heat sinks on whichthe output devices are mounted This temperat...

Page 14: ...drives the temperature sense test point U117A hasafixed window voltage of 6 2VviaZener D129 If heatsink temperature level exceeds about 130 C U117A output will cause both the positiva and negative OD...

Page 15: ...it and the positive HS Voltage Translator feed control circuit Also this circuit provides test point monitoring information Bi ODEP VZ mode control information and frontpanel ODER thermal reserve LED...

Page 16: ...mperature sense test point U117A has a fixed window voltage of 6 2V via Zener D129 If heatsink temperature leve exceeds about 130 C U117A output will cause both the positive and negative ODER amplifie...

Page 17: ...and U114D which in turn drive LH and LL respectively Also entering the U114 comparator networks are the PWR power relay engage PWRLOSS brown ou and FAULT any protection which shuts down the amplifier...

Page 18: ...NCED ERROR AMP GAIN STAGE 775VO 1 SEI S R1OO 4 99K R1O1 4 99K VOLTAGE _ TRANSLATOR LVA I ODEP 3 VOLTAGE 1 O O LCH 1 TRANSLATOR LVM 26dB JQITIUITV VARIABLE JSITIVITY GAiN STAGE WITCH OIAUK 4 t 1 o i T...

Page 19: ...gain n this stage Overall amplifier sensitivity may be set for26dB fixed gain about 5 1Vrms inpu 1 4V 4dBu unbalanced with 8ohmload or0 775V OdBu unbalanced with 8ohmload Since overall amplifier gain...

Page 20: ...nnector the error signal sense test point and the compression control circui Error Amp Amplifier feedback s summed with input audio and fixes gain from the input to this stage to the output of the amp...

Page 21: ...h augmentsthe other Soft Start Soft start circuitry controls the rate at which power is initially applied to the primary of the toroid transformers for the high voltage power supplies For ease of expl...

Page 22: ...start start waveforms on the Soft start block diagram Note DC pulse stretching circuit shown in Low Voitage Power Supply schematic cut away on page 11 When the output of U701A goes low the opto triac...

Page 23: ...rectifier in the low voltage supply R780 picks off the pulsed DC and U707D will if the voltage stoo high shift itsoutput to a low Whenthis happens the over volt therm redLED on the control module lig...

Page 24: ...ncy and wil interrupt the amplifier channel in the event of DC or lowfrequency The feedback loop is sensed for voltage and the current sense signal provides current information An RC network at the in...

Page 25: ...athlabelledTIMER STBY They are shown together since schematically they share a common control line to the C120 Soft start and PWR relay control circuitry Over Voltage and Thermal Switch information co...

Page 26: ...20 10 i t R328 S 1 3M J 9 8 1 R330 470K 15V R355 uni 6 8K LM339 14 MWI i 5V 1 f5V C184 To ODER Common Mode Output Current FAULT circuit In the event of high current in both the positive and negative h...

Page 27: ...p the audio Transformer Thermal The main powertransformers have built inthermal switches which open in the event of transformer over temperature In the event that the thermal switch opens in the chann...

Page 28: ...hanne 2 D706andD707formad odeORga e The output of theOR gate drives one input to U707B The other nput to U707B is from the DC pulse width control c rcuit U701B U707B op rales in a fashion similar to t...

Page 29: ...may have a reddish appearance and are normally on They dim and or extinguish in the eventthattheamplifier sthermal reserve sexhausted ODER indicators will also extinguish whenever the main supply rela...

Page 30: ...turned down counterclockwise fully n either mono mode Monaural amplifier operating modes are covered in detail in the MA 5000VZ Owner s Manual The discussion below primarily aides in understanding how...

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