What is your reasoning to believe there is not a SMPS in your mixer? The power supply schematic clearly shows one.
It is a switch mode power supply in my mixer. It’s not a switch mode power supply in my bass tube preamps.What is your reasoning to believe there is not a SMPS in your mixer? The power supply schematic clearly shows one.
I did buy a 200khz battery powered oscilloscope. Should I keep it or send it back? Here is what I have: https://www.arrow.com/en/products/1...sEGwepjKjD0hz-HFwWX3QAZ1kYQQuYbBoClAEQAvD_BwEOk. I guess we will see you when you decide to get back to this problem.
What I immediately don't like about it is there is no BNC connection for standard probes. That being said, it is suited for audio work. the SMPS switching frequency is probably lower than 200 kHz. My only concern is even at 10V per division, you can only read a peak of 40 volts, so you may need a x10 probe, IF the one you get with it isn't switchable between x1 and x10.I did buy a 200khz battery powered oscilloscope. Should I keep it or send it back? Here is what I have: https://www.arrow.com/en/products/1...sEGwepjKjD0hz-HFwWX3QAZ1kYQQuYbBoClAEQAvD_BwE
Nominal frequency for that switcher is 500KHz. You won't see any signal with a 200KHz scope.The scope would not give you the true signal. It can be lower in amplitude as well as distorted from the true value. The depends on how much above the 200 kHz the signal is.
Most probes these days are 100 MHz probes, so the true signal would likely pass through them (attenuated) with no problem.
I measure 130K in the circuit, so it is okay.Check R24, 150K 2W resistor. it may be open. If so, replace it with 3 x 47K 1W resistors in series. This lowers the voltage across each resistor. Some resistors seem to give up with high volts across them.
Another good old trick is to place a mains lamp in series with the power input to limit the current in fault conditions.
If the resistor is the value you say, it will be ok. All it does is charge the capacitor with enough volts to start the supply, then the control power is supplied through the circuit feeding D11.It’s not, so I’ll replace it with 3 47k 1 watt resistors with 5% tolerance. Do you think that that might fix the power supply?
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by Jake Hertz
by Jake Hertz