Re: 2nd QMX Build and it wont power on and an update on my old unit...
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Hello Devan
A technique I suggested for QCX troubleshooting was to bypass the signal generator resistor (120K in QCX, 100K R518 in QMX) with a much smaller resistor, say 330-ohms. Then the signals are enough amplitude that you can trace them through the LPF, BPF and trifilar transformer, with an oscilloscope. Signal tracing, oldest techniques, still valid. I don't think there's a problem in your PCM1804 or digital Signal processing. I'd guess it's in the filters or mixer. 73 Hans G0UPL
On Wed, Aug 30, 2023, 7:17 PM Devan Phillis < devan@...> wrote: Hans,
The trifiliar was one of the first things we did…. Also, I reflowed all the other places where enamel comes thru the board. I should mention that the 1804 gets warm… not hot but warm. I’ll look back try my emails with John and get an idea of where we were, it has been a while since I had the time to mess with it. I would really like to get the original going because it was one from Dayton and then the new one is obviously not. Also… I made a work around but a heads up, my 2X3 female socket connector was missing a pin. See attachment.
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