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Yeah that was my thought's toOK. 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 functioning one.
Thanks for the advice,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 you just end up chasing your tail all the time.
No i dont sorry, although i was thinking of buying an oscilloscopeDo you have access to an oscilloscope and a signal generator?
Thats great thanks, i think thats mainly where my interest lies with audio equipment, will those 2 pieces of kit be usefull?, if so i will buy them, thanksHello,
When you do only audio work, you can have a signal generator and scope for about 100 pounds:
https://www.amazon.co.uk/Topiky-Function-Generator-Portable-FG-100-default/dp/B083TGVZ3Y
https://www.amazon.co.uk/Digital-Oscilloscope-ETEPON-Source-15001K/dp/B07FPDY3DK
Bertus
Ok. I will try to be more explicit with my instructions.Thanks for the advice,
When you say input shorted, do you litteraly mean short + to -- where the input signal comes in,
Also when you say output, where exactly do you mean?
I can take as many readings and change as many parts as required but you need to be clear with your instructions,
As i said before, i am still learning, i know 12VDC single phase and three phase AC electric realy well, i do it for a job now,
Its the 0V part i have difficulty in understanding but i am getting better,
So, what would you like me to test ?
Thank you for your time and help, it realy is appreciated,
Pete
Is this a better option?Hello,
I was originaly looking for the nano scope, but that has a much higher price:
https://www.amazon.co.uk/Seeedstudio-109990013-DSO-Nano-v3/dp/B078YJYJDR
Bertus
Are these points still valid ?I have a post (about 10 posts back) with many many points for @bikemech to consider. I assume they are still valid?
I will try to xo this tomorrow and post my resultsTo 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, test resistor or speaker, on the output of the channel you are testing.
Connect + lead of your DMM to the O/P of the Channel under test and the - lead to 0V at the power supply.
Set your DMM to 2V d.c. or whatever range you have in that region.
Turn on your amplifier and check the voltage reading on your DMM.
It should be less than ± 100mV or preferably less than ± 50mV. If you get substantially more then you have a problem.
You will next need to check the quiescent current but we will deal with that on another post.