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1、 APA1400 APA1000 APA600 SERVICE MANUAL 1 0 2 3 4 5 6 7 8 9 10 1 0 2 3 4 5 6 7 8 9 10 SPCLIPTH PROT SPTH RLEEC APA1400 POWER CHANNEL 2CHANNEL 1 OFF ON SWITCHING POWER MOSFET AMPLIFIER CLIP PROT 1 0 2 3 4 5 6 7 8 9 10 1 0 2 3 4 5 6 7 8 9 10 SPCLIPTH PROT SPTH RLEEC APA1000 POWER CHANNEL 2CHANNEL 1 OFF
2、 ON SWITCHING POWER MOSFET AMPLIFIER CLIP PROT 1 0 2 3 4 5 6 7 8 9 10 1 0 2 3 4 5 6 7 8 9 10 SPCLIP PROT SPTH RLEEC APA600 POWER CHANNEL 2CHANNEL 1 OFF ON SWITCHING POWER MOSFET AMPLIFIER CLIP PROT RadioFans.CN SERVICE MANUAL APA1400/1000/600 INDEX - BLOCK DIAGRAM - FUNCTIONING DESCRIPTION - SCHEMAT
3、ICS - COMPONENTS LOCATION SCHEMA AND PART LIST - TESTING AND QUALITY CONTROL - TECHNICAL CHARACTERISTICS - WIRING DIAGRAM - CONFIGURATION DIAGRAM - MECHANICAL DIAGRAM - PACKING DIAGRAM RadioFans.CN RadioFans.CN author:Queraltdate:000519 approved: num:52.0007version:01.00 FUNCTIONING DESCRIPTION titl
4、e: POWER MODULE The amplifying stage basic structure is actually the one commonly used until now, this is, a push-pull mounted A-B class amplifier, using P-type (IRFP9240) and N-type (IRFP240) mosfets. The systems controlling core is a NE5534 OpAmp, which is internally compensated in order to obtain
5、 an amplifying gain ratio equal or greater than 3. The amplifiers feedback runs through a resistor and a capacitor associated to the OpAmps non- inverting input. Transistors BF871 and BF872 are common-base configured, becoming actually a current source structure. They accomplish a dual function: on
6、one hand, they polarise the mosfets gate-source junction, keeping them on their conduction knee. On the other hand, they carry out the OpAmps output voltage variations, referred to signal ground. The polarisation current adjustment is fixed by a 2k5 trimming potentiometer connected to the BF transis
7、tors base. This current is added to the current sources output, which passes through the BF-transistors load resistors. The bias current stability against temperature is fixed through the BD437 transistors. Their temperature- dependent base emitter voltage curve is used to alter adequately the curre
8、nt sources reference voltage. As a consequence, if the temperature rises, the reference voltage decreases, thus the gate-source voltage also does, and finally the bias current also decreases. The Zobel network, formed by a resistor-inductor-capacitor group, and which is located at the amplifiers out
9、put, intends to keep the amplifiers load impedance as constant as possible, no matter which load is connected to the stages output, or which signal frequency is to be amplified, in order to prevent an inverted-phase feedback signal. In order to avoid a DC offset on the output signal, a diac-triac ta
10、ndem system is used, which shorts the output to signal ground when the DC level is enough to get the diac triggered. To prevent this from happening while carrying audio signal (sine-wave, music), the diacs reference voltage is taken from a filter formed by resistor R149 and capacitor C124. The prote
11、ction circuitry supervises at any time the power consumed by the MOSFETS. The circuitry basically consists on two sections: MOSFETs drain current (Id) monitoring and drain-source voltage (Vds) monitoring. When the drain current exceeds a certain limiting value, a transistor (called control- transist
12、or) becomes conducting, together with an auxiliary circuitry (helper), formed by a transistor (which is the same type as the control-transistor) and a 82V Zener diode. This value determines the point where the auxillary circuitry starts to run. The helper- transistors base-emitter junction curve is
13、used to obtain a non-linear variation on the MOSFETS gate-source voltage control, and thus on their drain current. ECLER Sheet 1 of 2 RadioFans.CN author:Queraltdate:000519 approved: num:52.0007version:01.00 FUNCTIONING DESCRIPTION title: POWER MODULE ECLER Moreover, as the helper-transistors base-e
14、mitter current is temperature-dependent, the controlling circuitry (basically the control-transistor) compensates the safe operation area (SOA) drift due to temperature. If the MOSFETs drain-source voltage (Vds) drops too low, a second circuitry actuates to alter thecontrol-transistors triggering le
15、vel, obtaining a SOA-like curve section and a current stage, which can be adjusted adequately in order to maintain the MOSFETs power consumption as close as possible to its SOA. Moreover, the amplifier also includes an ANTICLIP system. When the amplifier reaches its clipping level, the OpAmp becomes
16、 unable to keep the system under control, and as a consequence V peaks appear at its output (15V power supply). This peaks are used to be rectified and sent to an optocupler (led- resistor) which modifies its impedance as a function of those peaks amplitude. The resulting impedance is part of a volt
17、age divider, together with the amplifiers input impedance. So, as the optocoupler increases its impedance, the amplifiers input signal level decreases until the system becomes stable. Also a dual-function temperature control circuitry is provided: - Temperature-depending control of the cooling fan s
18、peed, whose voltage supply is variable between 7 and 14 Vac. - Amplifier shutdown when temperature exceeds approximately 90C. The circuitry is formed byLM35D-type IC, which acts like a thermal probe, an amplifier, thermal probe level comparator and a 7805-type voltage regulator. The amplifier is res
19、ponsible for the cooling fan speed control. The comparator triggers a relay, which cuts off the MOSFETs bias current by shunting a 22W resistance to the BF-type transistors load resistors. This way, the output signal of the amplifier is effectively cutted off. The STAND-BY circuit. This circuit keep
20、s the safety relay closed for about 10 seconds, thus the MOSFETs bias current is cutted off during this period, until the whole system reaches again a voltage-stable situation. Due to this, hearing annoying transients and noises during start up through the loudspeakers is avoided. This delay is obta
21、ined by a RC-cell, where R=287K, and C=47F/50V. During start up, this RC-cells voltage smoothly rises until the 40106-type Trigger-Schmitt trigging level is reached, and the amplifier starts functioning. C=47F resets or discharges when the unit is turned off. During a short period of time, a BC817-t
22、ype transistor acts like a switch, connecting two 75W parallel resistors to C=47/50V. Sheet 2 of 2 RadioFans.CN RadioFans.CN RadioFans.CN RadioFans.CN RadioFans.CN RadioFans.CN RadioFans.CN RadioFans.CN RadioFans.CN RadioFans.CN RadioFans.CN RadioFans.CN author:Queraltdate:020430 approved: num:40.00
23、48version:01.01 C101100nFCXCN41000 C102100nFCXCN41000 C103100nFCXCN41000 C104100nFCXCN41000 C10547u/16FCCE100000 C10647u/16FCCE100000 C10747u/16FCCE100000 C10847u/16FCCE100000 C109100pFCXCN21000 C110100pFCXCN21000 C111100pFCXCN21000 C112100pFCXCN21000 C11322p 2%FCXCN12201 C11422p 2%FCXCN12201 C11522
24、p 2%FCXCN12201 C11622p 2%FCXCN12201 C11747u/16FCCE100000 C11847u/16FCCE100000 C11947u/16FCCE100000 C120C100n/63VFCCDK11000 C12247u/16FCCE100000 C123100nFCXCN41000 C124100nFCXCN41000 C1253300u/35FCCE213300 C1262200u/35VFCCE212200 C1274700u/100FCCE331525 C1284700u/100FCCE331525 C1294700u/100FCCE331525
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