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QCX mini-5volts

 

In circuit, 7805 regulator puts out?2.0?volts.? Of course, transceiver not working.
When I check output of regulator with output pin not connected to circuit, it puts out 5 volts.
With power off, continuity checks to all components served with 5 volts seems OK.? No opens nor? shorts to ground that I can find and no solder bridges. C37 tested out of circuit at 9.5 microfarads
Power in to regulator is 12 volts.
I have previously built working QCX mini, QCX and QCX+ in several frequencies.
This mini is a Rev1 PCB with T1.07a software.

Any help will be much appreciated.

Incidentally, I recall someone saying they have printed out the traces for the 5 volt circuits.? They would be helpful to me if still available.

Thanks and 73
Joe? ?VE7DHJ
 

?Joe

Can you connect a load resistor to the output pin of the regulator to test the 7805 on it's own? I haven't looked to see what current it should be supplying but ohm's law well give you the resistor value.?

73 Don ve3ids


On Thu., Dec. 16, 2021, 8:53 p.m. , <joehemus@...> wrote:
In circuit, 7805 regulator puts out?2.0?volts.? Of course, transceiver not working.
When I check output of regulator with output pin not connected to circuit, it puts out 5 volts.
With power off, continuity checks to all components served with 5 volts seems OK.? No opens nor? shorts to ground that I can find and no solder bridges. C37 tested out of circuit at 9.5 microfarads
Power in to regulator is 12 volts.
I have previously built working QCX mini, QCX and QCX+ in several frequencies.
This mini is a Rev1 PCB with T1.07a software.

Any help will be much appreciated.

Incidentally, I recall someone saying they have printed out the traces for the 5 volt circuits.? They would be helpful to me if still available.

Thanks and 73
Joe? ?VE7DHJ

 

It's most likely loaded down by a faulty circuit, not necessarily a short. Maybe a device is installed backwards, check electrolytic caps and semiconductors.?

Curt

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