Primare-A32-pwr-sm 维修电路原理图.pdf
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1、 PRIMARE A32 Power Amplifier Service Manual RadioFans.CN 收音机爱 好者资料库1. Technical Description. 2. Error codes. 3. Bias Adjustment. 4. Schematics. 5. Technical Specifications. Confidential ! This document is not allowed to show for third part without written permission from Primare Systems AB. This doc
2、ument is subject to change without notice. Author: Bjorn Holmqvist Primare Systems AB RadioFans.CN 收音机爱 好者资料库A32 Functional Description Features The Primare A32 power amplifier is a fully balanced design, this means that the negative speaker terminals are active, not ground as on an unbalanced desig
3、n. When performing measurements, test equipment (such as Audio Precision) that can handle balanced amplifiers must be used. The input impedance is 15K and the gain is 26dB. It is possible to obtain just above 250 undistorted watts at an 8R load (both channels driven). The frequency response are flat
4、, the A32 will drop down only -2dB at 100Khz. Standby The A32 is equipped with two standby modes, where standby mode 2 is the power save mode. In power save mode only the standby circuit will be powered by the small standby transformer placed on the digital PCB. Digital control and monitoring When p
5、ower is first applied and the standby button on the front panel are pressed down the A32 are going to initiate the startup sequence. Relay K1 will be turned on where after a small delay will follow before relay K2 goes active to disable the inrush limiters. At the same time bias are turned on by shu
6、tting down the voltage supplied to the optocouplers on the amplifier channels. After a 20 second startup delay for the amplifier to settle down the speaker relays are turned ON. During the startup sequence all safety parameters such as DC-offset and fuses will be monitored, if an error is spotted th
7、e amplifier will refuse to start and the standby LED will flash rapidly to indicate that an error has occurred. The error code can be read out by pressing the error check switch (SW1). Description of the error codes can be found on the next page. If the standby switch is pressed when the amplifier i
8、s in operate mode it will go to standby mode 1, which means that bias and speaker relay will be switched off. The standby LED is going to half light intensity to indicate that the amplifier is in this standby mode. If the standby button are pressed down for more than one second the amplifier are shu
9、tting down into standby mode 2 which means that bias, speaker relay and the two power relays K1, K2 are switched off. Only the standby circuit is still powered consuming just a few watt of energy. Temperature protection When temperature has reached 70 centigrade at the temperature sensors the speake
10、r relay and bias are going to be switched off, when the temperature have decreased 10 centigrade the A32 are going to be restarted. In practice this will mean that the warmest part of the heatsink will be around 75-80 centigrade when over- temperature protection cuts in. General Protection During op
11、eration mode DC-offset, fuse, temperature and AC-loss are constantly monitored, any abnormal function from these will immediately disengage the speaker relay and the standby LED will start to flash rapidly indicating that an error has been spotted. The error code can be checked by pressing the error
12、 check button (SW1), if more than one error at the same time a repeated press of the button will display the next error. DC-offset and over temperature will automatically resume to normal operation after a delay if the error recovers. Fuse error will not (latch), here the amplifier must be turned of
13、f and the fuses replaced before normal operation is possible. Trigger. If a 3.5mm teleplug are connected to the left trigger input (the right connector is the output) the function of the standby button are being changed to only be able to turn the amplifier into standby mode 2 directly. The standby
14、button cannot turn the amplifier on while the trigger is connected (trigger mode enable). The circuit will trigger at 2.5V and are highly immune against disturbances. The trigger are only able to control the amplifier between operate and standby mode 1. RS232 The RS232 port can be used for firmware
15、upgrading as well as controlling by Crestron compatible RS232 codes. Fuses Due to the large capacitance of the electrolytics bank, turn off the mainspower and wait minimum 15minutes before replacing a blown fuse. Make sure to replace a blown fuse with exactly the same type and value. Error codes LED
16、 Nr 3 2 1 Error 0 0 0 All OK 0 0 1 DC L+ 0 1 0 DC L- 0 1 1 DC R+ 1 0 0 DC R- 1 0 1 Fuse Rch 1 1 0 Fuse Lch 1 1 1 Overheated Bias Adjustment Critical for the adjustment are that the mainsvoltage is 230V or 120V exactly. The temperature in the facility must be constant during the adjustment procedure.
17、 Use the Bias test points and potentiometers (R1, R2) to adjust bias on each channel. The lower potentiometer is accessible thru a hole in the bottom of the amplifier. Bias test points Compare the voltage drop over all of the emitter resistors. These steps describe the Bias adjustment procedure, whi
18、ch is the same for both L& R channels. 1. Switch the amplifier on or if it has been on burn-in (test), disconnect input signal and loads. The A32 amplifier must be in operate mode, bias will be switched off in standby. 2. Let the amplifier run for 1h, without input signal. 3. Adjust the bias to 17mV
19、 measured on JP3, JP4 or JP2, JP1. 4. Check the maximum difference (voltage drop) over emitter resistors (R241, R243, R245, R247, R239, R237, R235, R233, R240, R238, R236, R234, R242, R244, R246, R248). The difference between them should not exceed 7mV. Higher difference might be due to a faulty tra
20、nsistor or Emitter resistor, also check and that the screw are tightened. 5. Wait 1h. 6. Measure the bias and if needed readjust to 17mV measured on JP3, JP4 or JP2, JP1. 7. Wait 1h. 8. Measure the bias and if needed readjust to 17mV measured on JP3, JP4 or JP2, JP1. 9. Wait 1h. 10. Measure the bias
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