Electrocompanient-25W-pwr-sch维修电路原理图.pdf

http:/users.otenet.gr/athsam/electrocompaniet.htm ith output of 25W per channel into 8ohms, this power amplifier, presents exceptional interest for he circuit is designed with regard to reducing T.I.M (Transient Intermodulation Distortion). bserving the circuit of amplifier, we will see that it is separated in four stages. The three first are e the first differential stage Q1 is BCY87 (Philips), in a metal case. The input impedance R1 of the Ferranti). the second differential stage Q4- BCY89 (Philips), trimmer TR1, adjusts for output offset d he third differential stage Q5-Q6, is supplied with current from current mirror Q8-Q9. These , 8, 7 and TR2 are a Vbe multiplier, in thermal contact with the output stage he output stage is the classic Darlington pair for positive and negative supplies. D4 & D5 protect W many, and it applies enough technological solutions, that we do not find in a lot of other amplifiers. T O full differential amplifiers (in thermal equilibrium, for minimal change in characteristic with temperature variation) and the fourth stage of the classic Darlington arrangement, with Vb multiplier transistor so set bias current in the output stage. In amplifier is very low 1.8K, compared to most amplifiers which are between 47K-100K. The two first differential amplifiers are supplied by current sources Q2 and Q3 ZTX384 ( The base of Q1 is applied the negative feedback via R18, R2, R4. Compensation for high frequencies is provided by R5 and C2. In voltage. The constant current sources are roughly 0.2mA for first stage and 0.4mA for secon stage. T function to increase the speed and the linearity of stage. Thermal balance is ensured as Q5, 6 9 are all in thermal contact. Q T the output transistors from speaker back emf. RadioFans.CN 收音机爱 好者资料库 A other point of difference is the driver stags are supplied with non symmetrical regulated power supplies of +19V and -44V and the final stage with and unregulated +/- 26V. This segregation of power supplies improves the Power Supply rejection ratio for low noise and decreases the intermodulation and the distortion. R1-3-19= 1.8Kohms R24-31= 2.2Kohms D1= 15V 0.5W Zener R2= 10 ohms R25= 2.7Kohms D2-3= 1N4148 R4= 12Kohms R28-29= 10 ohms D4-5= BY206 R5= 120 ohms R32-33= 56 ohms Q1= BCY87 (Philips) R6-7-27= 1Kohms R34-35= 1 ohms/5W Q2-3= ZTX384 (Ferranti) R8-13= 2.7Kohms R36-37= 1 ohms/5W Q4= BCY89 (Philips) R9-10= 1Kohms R38= 1 ohms/ 3W Q5-6= BD140 R11-12= 33 ohms C1-6-7= 100nF 100V Polyester Q7-8-9= BD139 R14-15-20-21= 10 ohms C4-5= 680nF 100V Polyester Q10= BD139 R16= 3.3Kohms C2= 2.2nF 100V Polyester Q11= BD140 R17= 4.7Kohms C3= 2.5nF 100V Polyester Q12-13= BD203 R18-26= 470 ohms TR1= 220 ohms Trimmer Q14-15= BD204 R23-30= 1 ohm TR2= 1Kohms Trimmer All R is metal film 1% except R34- 38 SPECIFICATIONS OUTPUT POWER25W/8 ohm - 40W/4 ohm DAMPING FACTOR160 8 ohm INPUT IMPEDANCE1Kohm SLOW RATE125V/s FREQUENCY RESPONSE 1W/8 ohm DC-1MHZ THD0.01% 12.5W TIM0.03% 12.5W S/N100dB RadioFans.CN 收音机爱 好者资料库