crown_macro-tech_ma-5000vz_sm电路图.pdf

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1、Notes MACRO-TECH 5000VZ OVERVIEW At first glance the MA-5000VZ looks a great deal Hke any other MA Series amplifier, except that t is physically larger and puts out more power. The internal structure of the MA-5000VZ is, however, quite different from other models in the MA une. To the user, this one

2、 is like the others, but with a f ew more f eatures. To the technician, this amplifier representsaradicaldeparturefromthenormalCrowndesign. Previous chapters covered the normal, this chapter shall endeavorto take the MA-5000VZ as a unique entrty. The amplifier s protected from all common hazards tha

3、t plague high- power amplifiers, including shorted, open or mismatched loads, overloaded power supplies, excessive temperature, chain-destruction phenomena, input-overload damage, and high-frequency blowups. The unit protects loudspeakers from DC in the input signal and from turn-on and turn-off tra

4、nsients. It also detects and prevens unwanted DC on the outputs. Additional protection features 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 circuit, when switched on, prevens excessi

5、ve bass frequency cone excursions below the audible frequency range. It operates essentially as a band-pass filter. The low frequencies are rolled off at 18dB/oclave with a -3dB crner of 35 Hz (Butterworth response). Ullra-sonics are rolled off wilh a second order Bessel response and -3dB crner of S

6、OkHz. A compression circuil in each channel may be switched off, on slow, or on fast by swilches on Ihe rear panel. This compressor is aclivaled by eilherinputoverloadordstorton(clpping). Compression ratio is infinite (operates as a peak limiter). Thefour-quadrant lopology used in the grounded oulpu

7、l slages is called Ihe grounded bridge and makes full use of Ihe power supplies. This patentad lopology also makes peak-lo-peak voltages available lo the load which are twice the vollage any output device s ever exposed to. The grounded bridge is covered in detail in the BASICS seclion of this texl.

8、 MA-5000VZ - 1 RadioFans.CN 收音机爱 好者资料库 Notes The two channels may be used together to double the voltage (bridged- mono)orthecurrent(parallel-mono)presentedto the load. Thisfeature gives the User flexibility in maximizing the power available to the load. Output power of the amplifier is rated as fol

9、lows (assumes 120V 60Hz AC mains): StereoSohm: 1300W/CH Stereo4ohm: 2000W/Ch Stereo2ohm: 2500W/Ch Bridge Mono 8 ohm: 4000W Bridge Mono 4 ohm: 5000W Parallel Mono 2 ohm: 4000W Parallel Mono 1 ohm: 5000W Macro-Tech amplifiers utilize a wide bandwidth multiloop design with state of the art compensation

10、 techniques. This produces ideal behavior and results n ultra-low distortion vales. Aluminum extrusions have been widely used for heatsinks in power amplifiers due to their low cost and reasonable performance. However, measured on a watts per pound or watts per volume basis, the extrusin technology

11、doesnt perform nearly as well as the thermal diffuser technology developed for Macro-Tech power amplifiers. Our thermal diffusers are fabricated from custom cut fin stock that provides an extremely high ratio of rea to volume, or rea to weight. All power devices are mounted directly to massive heat

12、spreaders that are electrically hot. Making the heat spreaders electrically hot allows MA-5000VZ: CHANNEL1 SHOWN 4 (ooep) MA-5000VZ Overall Block Diagram D (ODEP) 2 - MA-5000VZ RadioFans.CN 收音机爱 好者资料库 improved thermal performance by eliminating the insulating interface underneath the power devices.

13、The chassis itself is used as part of the thermal circuit, and this maximizes utilization of the available resources. Air flow in this amplifier is front to rear, also a departure from other Macro-Techs. Fan speed is a function of ODEPIevel. AlthoughODEP was covered in detail in the BASICS section o

14、f this text, the specif ics of the MA-5000VZ ODEP circuit are unique and will be covered here. Notes OUTPUT STAGE CIRCUITRY The MA-5000VZ, like other Macro-Techs, uses the grounded bridge. It does differ, however, in certain aspects. For example, quadrants use four devices n parallel ratherthan the

15、normal mximum of three. Output stages are also physically built in a modular way, for ease of field replacement. Electrically, there are also a few differences. Bias servo networks consist of two transistor devices per Vbe multiplier (one set for high side, one set for low side). Also, ODEP affects

16、the low side as well as the high side by stealing 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 stealing drive. Circuitry on the positive and negative output modules nclude bias circuitry,

17、 current limit circuitry (the MA-5000VZ has two speed current limit), last voltage amplifiers (LVAs), pre-driyers, drivers, and output devices. Temperature sensors are also mounted to the heatsinks va the output modules. These deliver nformation to the main module which computes actual calibrated te

18、mperature for ODEP and temperature measurement. H-15V R571 2.7K Positive (NPN) Output Stage Thermal Sensor Circuitry U50O V. LM334 r L 3 R572 r 227 O.5OW R584 2.7K +TEMP1 : The positive LVAs (Q501, Q502, and Q503)convert the negative output of the voltage translator stage to a positive drive voltage

19、 for the NPN High Side (HS) predriver. There are three LVAtransistorsin parallel due to the very high voltages (therefor higher current and thermal requirements) that are present when the power supply is in high voltage mode. D522 prevens the +LVAsfromproducinga high negative output to the HS NPN st

20、age. MA-5000VZ - 3 RadioFans.CN 收音机爱 好者资料库 Notes Q507, Q508, and Q509 are the -LVAs and are arranged n mirror image to the +LVAs, ncluding D513. On the positive side D514, D515, and C506 va the +LVAs act to limit slew rate. D514 and D515 also prevent dangerously excessive current through the LVAs. D

21、516, D517, and C507 are the negative HS mirror image. Q534 and Q540 provide two-speed current limiting n the output stage. Sense lines are arranged such that excessive current through any single HS output device will result in current limit protection. Q535 and Q541 are the negative side mirror imag

22、e. Q503 on the positive output module works in tndem with Q505 on the negative output module as a Vbe multiplier circuit. They produce and, with great stabilily, control biasforthe High Side NPN and PNP devices. Potentiometer R505 is used precisely set bias voltage. Bias voltage is easily measured f

23、rom pin 2 (hot) to pin 4 of ATE ports TP1 and TP2. Refer to section 2 for appropriate test procedures. Q504stheHSNPNpre-driverandQ511 istheHSNPNdriver. These devices are biased class AB for ultra low distortion in the zero-crossing regin. Q513, Q515, Q517, and Q536 are the HS NPN output devices. The

24、se devices are biased class B, in soft cut-off, Together with driver and pre- driver, they function as a three-deep Darlington. The output devices work n parallel as a giant composite. The over-all bias topology is referred to as AB+B, originally conceived and patented by Crown engineers in 1966. Th

25、is s still the most efficient, stable, and distortion free method used today. Positive LVA, Portion of HS Bias, BIAS U Emitter Sense Output Audio 4 - MA-5000VZ D506 is theflybackdiode forthe HS NPN output quadrant. In the event that a back EMF (flyback) pulse exceeds power supply voltage, the flybac

26、k diode will shunt this voltage to the supply in order to protect the output devices. PNP pre-drivers, drivers, output devices, and flyback diode D508 are a mirror image of the NPN side. Overall the High Side of bridge operates much like a conventional output stage, but the Low Side (LS) is quite un

27、ique. The LS senses output voltage and common (ground) buss potential. The audio output is inverted by U503. Also in the U503 input circuitry are static and dynamic balance controls. These controls provide a fine balance of the grounded bridge. Output of the op-amp drives the LS pre- driver circuits

28、 through the LS bias network. LS bias s controlled in a fashion similar to that of the HS. Two transistors, Q529 and Q530, along fix LS bias voltage as measured from pin 15(hot)topin13ofapplicableATEportTP1 orTP2. Potentiometer R556 adjusts bias in the LS. Diodes D504 and D505 control polarity of ap

29、plied LS drive signal. Via the bias transistors signal s delivered to the bases of the pre-drivers Q527 (NPN) and Q528 (PNP). Pre-drivers, drivers, and output devices in the LS oprate class AB+B, exactly like the HS. The major difference s that rather than driving a load, the NPN and PNP stages cont

30、rol the ground reference for the high voltage rails. As the HS NPNs conduct, LS PNPs conduct, and vice versa (as explained in section 4.2.1). When the ODEP circuit senses that limiting drive is necessary to prevent a dangerous thermal condition, t provides an output which limits drive Notes +VCC1 OU

31、TPUT POSITIVE SECTION +VCC BUSS BAR + LVA H-VCC1 Q513 Q515 Q517 Q536 C5O6 220pF _L C510 O.O1 D5O6 High Side Predrivers, Drivers, Output Devices, and Flyback Diodes. Notice the various sense lines. These are used for various functions such as VZ switching sense and protection features. MA-5000VZ - 5

32、-I-VCC1 o I-15VI-15V C524 2OOpF R552 1OO R553 1OO To NPN LS Predriver D518 D5 J D4 y H I C52 10p D521 N d RS56 500 4 1 LOW S BIAS 6 = f 5 5 1K k 4 6 H534 T D507 12 X 2W C520 r- 0.022 R582 0. 33 5W S Q538 V| Q51 r R536 0.33 S 5W i BUrj S R538 / 0.33 S 5W S i Q523 R54O 0.33 5W -*SV R542 4. 0. 3 50W rN

33、r1Jl-t Ql ice; n A c( Q525 470uH N - rVVN . *T R544 R546 51 100 C522 0.033 | kr R550 13K ni Low Side of Bridge: including P Driver, Output Devices, and Fl Diode on the NPN side. LLL 6 - MA-5000VZ to the output stages. For the HS, this limiting s accomplished on the main module and isexplained nsecto

34、n4.4. Forthe LS, ODEP provides (via wires labeled LL) a signal which limits bias feed to the LS output devices. This is accomplished through current mirrors Q532 and Q531 (LS NPN quadrant), and Q542 and Q543 (LS PNP quadrant). Notes POWER TRANSISTOR SPEAKER LOAD POWER TRANSISTOR VZ POWER SUPPLY POWE

35、R TRANSISTOR SPEAKER LOAD POWER TRANSISTOR VZ STAGE VZ STAGE Low Voltage, High Current Mode VZ POWER SUPPLY POWER TRANSISTOR SPEAKER LOAD POWER TRANSISTOR VZ STAGE VZ STAGE High Voltage, Low Current Mode VZ POWER SUPPLY The VZ supply in the MA- SOOOVZworks, inconcept, very much like the MA-3600VZ. F

36、or the sake of completeness, some conceptual things will be duplicated here. VZ means Variable Impedance and is the ame of Crowns patented articulated 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 enough

37、to handle the mximum voltage and current necessary for the amplifier to drive its mximum rated power into a specified load. In the process of fulfilling this requirement cnventional power supply designs produce lots of heat, are heavy, and take up precious real estte. And its no secret that heat is

38、one of a power amplifiers worst enemies. According to Ohms Law, the bigger the power supply, the more heai the power transistors must dissipate. Also, the lower the resistance of the power transistors, the more voltage you can deliverto the load. But at the same time that you lower the resistance of

39、 the transistors, you increase the current passing through them, and again ncrease the amount of heat they must dissipate. An articulated power supply, like VZ, can circumvent much of this problem by reducing the voltage appliedto the transistors when less voltage is required. MA-5000VZ - 7 Notes Re

40、ducing the voltage reduces the heat. Since the amplifier runs cooler, you can safely pack more power into the chassis. The VZ supply is divided nto segments to better match the voltage and current requirements of the power transistors. Remember that audio signis like music are complex waveforms. For

41、 music the average level is always much less than the peak level. This means a power supply does not need to produce full voltage all the time. The VZ supply is divided into two pars. When the voltage requirements are not high, it oprales in a parallel mode to produce less vollage and more current.

42、The power transistors slay cooler and are nol torced lo needlessly dissipate heal. This is Ihe normal operaling mode of Ihe VZ power supply. When Ihe vollage requiremenls are high VZ swilches to a series mode to produce higher vollage and less currenl. The amplified oulpul signal never misses a beal

43、 and gels full vollage when it needs ilnot when il doesnt need t. Sensing circuilry walches Ihe vollage of Ihe signal lo delermine when GROUNDEDBRIDGE OUTPUT STAGE Input VZ Power Supply R = Switch Resistance 8 - MA-5000VZ to switch VZ modes. The switching circuitry is designed to prevent audible swi

44、tching distortion to yield the highest dynamic transfer functionyou hear only the musi and not the amplifier. You get not only the mximum power with the mximum safety, you also get the best power matching to your load. Actual current flow with power supply and grounded bridge operating together is s

45、hown on the previous page. The individual components are shown below. Upstream of the toroid transformer, though not shown, is where shutdown protection and soft- start circuitry taps in to control AC mains nput to the power supply. The VZ Control circuitry senses audio level and switches the articu

46、lating VZ supplies to either parallel (high current) mode for lower level audio, or series (high voltage) mode for high program peaks. Notes ToroidBridge 1 In both examples it can be seen that when the MOSFET switch is off, the dual supplies are torced to oprate n a parallel mode. Audio level is sen

47、sed via a line tapping off the NFb loop. When audio level s rising and at about 80% of the parallel mode supply voltage, the MOSFETs (the switch is actually a three-device composite switch) are turned on. No current will flow through either of the control diodes (D810 and D811, as shown for channel

48、1) because reverse polarity is applied through the MOSFET switch. Since this happens to both rectifier sources at the same time, and the negative side of Bridge 1 s then shorted to the positive side of Bridge 2, the supplies are forced to oprate in series mode. Like two batteries, the supplies will

49、provide double voltage in series mode, double current n parallel mode. Although shipped from the factory n normal VZ mode, the user may switch modes to lock low voltage (high current), lock high voltage, or oprate the supply in Bi-ODEP mode. Bi-ODEP is similar to normal VZ MA-5000VZ - 9 Notes mode, except that n the event ODEP s activated to protect the amplifier, the VZ will automatically lock into low voltage (high current) mode. While this mode of operation will cool the amplifier more quickly in the event that the thermal reserve s exhausted, it may cause voltage cl