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  1. WHONOES

    Stage Line 500W amp repair project

    How have you got the range switch set. You need it fully counter clockwise for the circuit to be set to 1:1.
  2. WHONOES

    VDO Voltmeter

    Further. All IC's require a minimum voltage to function correctly below which they will either not work at all or produce very erroneous results. A 6V battery could easily drop some way below it's nominal voltage meaning any circuit designed may not function at all or at best incorrectly.
  3. WHONOES

    VDO Voltmeter

    All voltmeters start life as a current meter. They just have a resistor in series with the armature coil so that it takes a certain voltage to develop the required current through armature coil for full deflection. If you could get inside whatever meter you choose to use, you should find a...
  4. WHONOES

    VDO Voltmeter

    Can't you use a 100μA meter that looks the part and put a resistor in series with so that it reads the correct voltage. It would save all the messing about with voltage doublers.
  5. WHONOES

    Why is it PNP instead of PPN for transistors

    Ah, James Clerk Maxwell a Scotsman. One of the cleverest people the most people have never heard of. Even Einstein was in awe of him. He calculated the speed of light; Predicted the presence of radio waves which arose from his work on electricity. He also did a lot of work on colours and how any...
  6. WHONOES

    Three way switch selection for switching aux phono output

    You are right. That's what I intended to say but got it back to front. See the switch I recommended.
  7. WHONOES

    Three way switch selection for switching aux phono output

    It also avoids connecting to sources together.
  8. WHONOES

    Three way switch selection for switching aux phono output

    The rotary switch you identified is the sort of thing you want. I would advise using a make before break such as the one below. CK1025 Lorlin, Rotary Switch, 6.35 mm, 6 Position | Farnell
  9. WHONOES

    Stage Line 500W amp repair project

    I make labels for my projects using Autosketch as mentioned before. I then laminate them which makes them very sturdy. I then attach them with double sided tape.
  10. WHONOES

    QSC Power Amp gets hot

    Can you check the Base - Emitter voltage on each of the output transistors in its quiescent state i.e. with no amplification taking place. Also, check the d.c voltage on the output of each amplifier across their output terminals under the same conditions.
  11. WHONOES

    Stage Line 500W amp repair project

    I use Autosketch to do such things. Sadly it is no longer available. There are a number of free CAD packages around. Try the link below. I have never used it but it might be worth a try. Free CAD Software | Draft it Free | Cadlogic
  12. WHONOES

    Three way switch selection for switching aux phono output

    A 2 pole 3 way rotary switch would be better.
  13. WHONOES

    QSC Power Amp gets hot

    Do both channels work?
  14. WHONOES

    Stage Line 500W amp repair project

    Good plan with the Sig' Gen'.
  15. WHONOES

    Stage Line 500W amp repair project

    It's always good to take a little time to consider where you are going to place you bits and pieces so that you can get them in a reasonably logical order. It can be quite irksome to have to rip everything out and start again. The main thing to be wary of when mounting the board is that you...
  16. WHONOES

    Power supply overheating

    I would imagine that if the power supplies are as your documentation dictate then the problem is with one or both of your power amps'.
  17. WHONOES

    Stage Line 500W amp repair project

    Looks about right. Which way round have you fitted your IC's. I can't see from the picture. Can you get a clear close up picture.
  18. WHONOES

    Stage Line 500W amp repair project

    Parcel on its way.
  19. WHONOES

    LC parallel tank circuit

    Have a look at the link below. It explains about basic transistor biasing. Transistor Biasing and the Biasing of Transistors (electronics-tutorials.ws)
  20. WHONOES

    Stage Line 500W amp repair project

    On post #586 can't find the connections you are referring to. When making these references can you please include the sheet number and grid reference of the points you are referring to!
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