Search results

  1. WHONOES

    MOSFET equivalence

    A schematic of some sort is absolutely vital as my crystal ball has a permanent malfunction.
  2. WHONOES

    Stage Line 500W amp repair project

    Further to post #476. Ideally you would use it on a Laptop as it would be electrically floating.
  3. WHONOES

    Stage Line 500W amp repair project

    I agree with Bertus. Farnell is a very good place to start. As an after thought, you could start with a virtual Scope. That is a software download that lest you use your audio card as a Scope. Some come with Sig' Gen' software as well. Google "Virtual Oscilloscope". Could be useful to get you going.
  4. WHONOES

    Stage Line 500W amp repair project

    If you have the patience to do so then yes.
  5. WHONOES

    Stage Line 500W amp repair project

    They look Ok. Time to try them out one at a time. Ideally you should check them out with your Scope and Sig' Gen' using a high power resistor for the load. This is mine.
  6. WHONOES

    Stage Line 500W amp repair project

    Good on you. Being prepared to listen and learn is vital. It enables you to sit on the shoulders of those with experience that have gone before and gain the benefit of their knowledge.
  7. WHONOES

    Stage Line 500W amp repair project

    Just to clarify, If I say O/P it means the actual Power Amp' output. If I mean Output Transistors I will say O/P transistors or I might say O/P stage. I/P has been clarified elsewhere.
  8. WHONOES

    Stage Line 500W amp repair project

    If that reading is just for the O/P stage then that is fine. Just need to check the other channel now.
  9. WHONOES

    Stage Line 500W amp repair project

    IMHO I think you would be better off with this Mds-3200a dds nc dual channel function signal generator frequency meter ttl wave Sale - Banggood.com Sig' Gen'. As it is a bit more future proof. And the following Scope Hanmatek DOS1102 Digital oscilloscope with 2 Channels and Screen 7 inch / 18...
  10. WHONOES

    Stage Line 500W amp repair project

    Hi again. No need to repeat tests. Results seem reasonable though the R.H Channel is a little on the high side. The idea was to short the junction(s) of the component mentioned to 0V so that there is absolutely no input to the amps whatsoever and the input is effectively grounded. You now need...
  11. WHONOES

    Replace IC 4049

    One thing that nobody has mentioned is the very limited source / sink currents available from CMOS logic.
  12. WHONOES

    Stage Line 500W amp repair project

    To check the output voltage, short the junction of R69 and C42 for the R.H. channel or R12 and C34 for the left hand channel to the nearest 0V connection on the PCB. You will sometimes see 0V referred to as Ground. These are not to confused with Mains Earth. Next make sure there is no load...
  13. WHONOES

    Stage Line 500W amp repair project

    Ok. I will try to be more explicit with my instructions.
  14. WHONOES

    Stage Line 500W amp repair project

    Those two items will be of more use than you could possibly imagine. They will make your fault finding so much easier. You will have to take a little time to get accustomed to them, especially the scope where you will have interpret what you are seeing and how to set it up. It won't take too...
  15. WHONOES

    Stage Line 500W amp repair project

    Do you have access to an oscilloscope and a signal generator?
  16. WHONOES

    Stage Line 500W amp repair project

    I think you need to go back a step and measure the quiescent current as I suggested earlier. Also, measure the d.c voltage on the output with no signal present and the input shorted. This should be low, certainly less than 100mV. You really must get one bit at a time working correctly otherwise...
  17. WHONOES

    Stage Line 500W amp repair project

    OK. That more or less answers my question. I was interested in how much quiescent current is flowing in the output of the working amp'. I suggest you now use the working amp as a template for the non working one. Take strategic voltage readings form the working one to diagnose and fix the non...
  18. WHONOES

    Electro plating power supply

    I would advise against using a very large 100Ah lead acid battery because if you accidentally short it out currents in the range of 100's of amps will flow and result in a lot of damage most likely causing a conflagration. Also I used to do a bit of gold plating many years ago and suggest that...
  19. WHONOES

    Stage Line 500W amp repair project

    IT's good that you have the right hand side working now. Have you tested with any audio or a signal generator? It would be worth removing the fuse from the + supply and inserting your DMM across the fuse receptacle and switched to a current range, probably 200mA, and then switch on and see what...
  20. WHONOES

    Stage Line 500W amp repair project

    Were those voltages taken with Q6 and Q9 removed. Have you replaced the output transistors as well? The figures you quote are quite reasonable. I assume they are referred to 0V.
Top