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  1. Arouse1973

    Stage Line 500W amp repair project

    No it's ok. When we say lower and upper end it's looking at the diagram the way it is drawn. The upper end is nearest the top of the drawing, so the supply. The lower end is the other side of the resistor where it connect to the base of the transistor. Edit: Lower end or bottom end
  2. Arouse1973

    Stage Line 500W amp repair project

    Maybe the fan should have kicked in normally in a fault condition and this was stopping it. I don't think it's related to the fault LED. Adam
  3. Arouse1973

    Stage Line 500W amp repair project

    Then another test. Remove Q46 and use you resistor lead you just made and connect one end to the +45V terminal and the other end dab it on to the top of R119. Does the LED go on and off? This will prove the rest of the circuit is working. Sorry if you have done this before. Adam
  4. Arouse1973

    Stage Line 500W amp repair project

    Oh Well done, I thought you had to de-solder it. Ok do the other bits first then remove and retest. Then do the resistor test I just mentioned. With and without the transistor. Adam
  5. Arouse1973

    Stage Line 500W amp repair project

    See if you can find a 1K resistor or something around that value. Then attach one end to a piece of wire and connect that to 0V. With this new lead with the resistor hanging of it connect the other end to the bottom of R108. If this part of the circuit is ok you should measure half the voltage...
  6. Arouse1973

    Stage Line 500W amp repair project

    Not for the moment.
  7. Arouse1973

    Stage Line 500W amp repair project

    Another thing is turn the power off and measure the resistance across the emitter terminal and the base terminal of Q46 with leads both ways around. That's from the label marked +45V (Not +45VL) and the lower end of R108. Adam
  8. Arouse1973

    Stage Line 500W amp repair project

    Yes that's right. If conducting correctly it should have approx. 50 V difference between it's terminals which it has. I think all the voltages you have measured are correct apart from the R108 voltages. So we know that R108 is ok, you measured it. Now did you defiantly remove Q46 when you...
  9. Arouse1973

    Stage Line 500W amp repair project

    No the zener is doing this. Adam
  10. Arouse1973

    Stage Line 500W amp repair project

    Yeah top I meant power in side. That's why you measured 0 V across R108 then. Thanks Adam
  11. Arouse1973

    Stage Line 500W amp repair project

    Ah I thought you meant R117 also, sorry. Can you when you get time measure the top of R108? Adam
  12. Arouse1973

    Amplifier circuit, need some help on high freq and low input voltage

    Wireless power is quite a complicated subject to get right. I know! You need to supply the details of your coils, size and shape, value of inductance and turns, wire used and series resistance. Also the distance you are hoping to be able to transfer this amount of power. Adam
  13. Arouse1973

    Stage Line 500W amp repair project

    Do you measure different voltages now from last time. What is the voltage on the top end of R108? Adam
  14. Arouse1973

    Help with a Data Acquisition Project with AT89S52

    I have done something similar this week with an Arduino Nano. I wanted to measure the voltage of a battery as it was discharging. I connected it to the A to D port of the Arduino and modified one of the many standard sketches that come with it. The Arduino IDE comes with something called a...
  15. Arouse1973

    led drivers

    Hello That looks ok. The 6.6 A is the maximum current you can draw. Thanks Adam
  16. Arouse1973

    Stage Line 500W amp repair project

    Do you know what the +45VL reading is? Adam
  17. Arouse1973

    Stage Line 500W amp repair project

    That's really odd, you measured 0 V across R108. That means either the meter didn't measure it correctly, the resistor is short circuit or it there is no current through it. Adam
  18. Arouse1973

    Stage Line 500W amp repair project

    Oh ok, is that quite feasible for a 500W amp to drop 20 odd volts with the output transistors connected? Cheers Adam
  19. Arouse1973

    Stage Line 500W amp repair project

    Hello Bikemech How did you measure the 66.2V, just curious. With respect to what terminal. Thanks Adam
  20. Arouse1973

    ring oscillator with stable frequency

    Another method that may work is to use large value resistor between the gates and the outputs this uses the resister and the very small gate capacitance to increase the propagation delay. Adam
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