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Evan, Good "general debug chart" to make a copy of and place in your QMX Debug Book. 73 Kees K5BCQ

Evan Thanks for the diagram and feedback.? I also have a short on VDD to ground with the boards removed. Lesson learned, the hard way! David VK4JM

Hi David, I believe that I had a similar issue. I removed both SMPS and measured the resistance on the 3.3-volt and 5-volt rails on the mainboard. The 3.3-volt rail measured 0 ohms. I tried removing

Unfortunately, NIL, Nada, nothing during the 1300Z session and not at home in the evening otherwise we could have made at least one qso Luc!

I have a QMX Rev 1 80-20m board that was working well until an issue with an intermittent power connection. The 3.3V SMPS looked like it had failed so I replaced both SMPS boards.? Unit then powered

Took my QMX on a POTA field trip this afternoon. Got all set up then tried to send QRL?, but no power out! Rebooted the QMX, checked cables, still nothing. What's that S on the display? Looked up and

Maybe yes - R.I.P.??? :-( Or there is a tiny solder bridge somewhere from the VDD rail to ground? Maybe around the STM chip on one of the sides of the PCB? The VDD rail goes also in the region of

Thanks again Ludwig. I measure 12.35 ohms at that connection between VDD and GND. I suspect I have partially killed the STM chip.

Hello Jirka, low at the gate should be only from 0.25 sec after switch on the QMX until it's off. When you see 0.75 V maybe the controller is working? ok, i t's a signal direct from the controller.

I repeat my unanswered question here. Reading the postings in this group, I understood that at least the Zenner Diode on the 3,3V Switching Power Supply Board had been changed against one with a

Hello Mike, good news!!! It's phantastic! It was my pleasure to provide some help. In your tabel the drain of Q511 is now not all the time on 0V like before. How could you fix this? If it doesn't

I built QMX ver. 3 and the rig worked fine. Yesterday I was doing some measurements on the PA and the rig shut down. After unplugging the oscilloscope, it wouldn't turn on. I found that the 5 V and

Kit built, low band, very odd symptoms. Initially had a few cw qsos and during transmit, crackling in audio followed total loss of the receive signal. I had to switch rigs to continue the qso. Rf out

John and Ludwig, I have very promising news! I have replaced all components except L510 and Q507.? I have great BNC center pin sine wave scope output signals on 20M, 17M and 15M [LPF-0 & LPF-1]!?

Hello Dave, a similar behaviour here (until today I didn't use the presets.) - Going with the left encoder to 80 m. - Recall a frequency in the 20 m band to VFO A.. - This frequency is shown? but the

Dave, I haven’t verified the issue with my presets that you found yet, but your post got me to thinking about receiving WWV. ? So the following falls into the category of “wouldn’t it be cool

Hello Gerry, wish you success and hope to hear about soon. 73 Ludwig

Hello Scott, don't never say never... but to me it's hard to belive a toroid could cause this problem. E.g. the signal ADC_5V is going from the pin header straight to the controller. All it's very

Hey Ludwig... This is great information. Many thanks. Hopefully this will help me locate the problem. Cheers Gerry

That’s a good idea filing a flat on the screw. It barely fits next to that ic. I think I’ll do the same thing. That will also keep from spinning the screw head in the pcb and scraping it any