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This scanned manual is well done in that most all the pages except for one is straight and clear- the way I would do them. One page was upside down but that happens. For the money that is charged on this site you get a pretty good deal. Now with complex repairs, I still prefer to us paper manuals which I have to buy at stereomanuals but the one I got here was much less than the $45 he was charging but this is a larger than normal manual for three different units. I am a picky manual user because I have used original manuals from Sony and Teac.
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Very useful service manual, was exactly what i needed.Good quality,reasonable price.Thank you.
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Acurate informations inside the SM and I could repair my old Sansui SC-3330 without any problems. Thanks.
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I used it to repair a NAD 7030, but unfortunately, the 7045 is different !
But documentation was useful.
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Content A4 and A3 format pages. Exactly what I needed to restore my old receiver.
f1723 / FP7317 / L1702 / vf17 / FP17 8. Power Board Operation Therory
8.1 Line filter consists of C801, T801, C802, C803, C804, C837, C838. It eliminates high frequency interference to meet EMI�s requirement. 8.2 Rec & Filter Bridge diode D801 converts AC source into pulsed DC. This pulsed DC is smoothed and filtered by C805. R802 is an NTC ( negative thermal coefficient ) resistor, used to reduce inrush current to be within safe range. 8.3 Power transformer : T802 converts energy for square wave from power source C805 to secondary side to generate +12V and +22.5V. 8.4 Output : The square wave from T802 is rectified by D809, D810, then filtered by C817, C822 to generate +22.5V and +12V respectively. 8.5 Driver : Q803 drive T802 from PWM control of I801 for power converted. 8.6 FB : Negative feedback CKT consists of photo coupler I802 and adjustable regulator I803. It can maintain output voltages +22.5V and +12V at a stable level. 8.7 PWM : 8.7.1 8.7.2 Start : When power is turned on. C807 is charged a 15 volt and a starting current above 40uA to pin 7 of I801. I801 starts to oscillate and outputs a pulse train through pin 6 to drive Q803. OPP : When Q803 turns on, C805 supplies a linearly increasing triangle current through the primary inductance of T802 to the driver Q803, once the peak value of this current multiplied by R811 exceeds1 volt, pulse train will be turn off immediately to protect Q803, T802 from being burned out. 8.7.3 Regulation : If output voltage +22.5V goes up, the R terminal of I803 gets more bias, accordingly photo transistor and photo diode flows more current. The voltage of pin 2 goes up too, making the pulse width of pin 6 to become narrower. So the output voltage +22.5V will be pulled down to a stable value. 8.7.4 OVP : If +22.5V goes up too much, the induced voltage on pin 4 of T802 becomes large also. Suppose that it is over 18 volts, ZD801 conducts, pin 3 of I801 is pulled up over 1 volt. The pulse train at pin 6 goes down to zero, shutting Q803 off immediately. 8.7.5 SCP : If output terminal is short to ground, photo transistor does not conduct, hence Q806 does not conduct either. Then oscillation of I801 is stop, shutting Q803 off immediately.
HPD-K17AA Power Board Block Diagram
Line Filter
Rec. & Filter
Power Transformer
Outpur Rec. & Filter
PWM
Driver
FB
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