Re: Select Button on Alignment QCX+ 20m

Richard M0AUW


Measuring with power on and, on the front panel,  I'm getting 1.14 volts with the left button depressed all others are correct. So, I'm presuming it's definitely the left button with some sort of cold solder joints, so I will recheck.

Many Thanks - Richard M0AUW

From: <> on behalf of Steven Dick <sbdick@...>
Sent: 07 September 2020 22:02,To: <>
Subject: Re: [QRPLabs] Select Button on Alignment QCX+ 20m
The buttons are all multiplexed on a single line to share a single ATMega328p pin due to pin limitations.  See schematic explanation page 163 of the QCX+ manual.  If you have power on and, on the front panel,  you look at the ungrounded side of R46 (10K), you should see zero volts if nothing is depressed, +5V is the rotary encoder button is depressed, about 4.5 volts if the right button is depressed, and about 3.76 volts if the left button is depressed. You cal also look at the ATMega328p pin 26 for these voltages. There may be a bad solder joint or wrong values or intermixed R44, R45, or R46 resistors. If the voltages all look good, then with power off, do a direct resistance measurement from the ungrounded side of R46 right to the ATMega328, pin  26. It should be zero ohms or you have a bad solder joint or front panel connectors not fully mated.

-Steve K1RF

------ Original Message ------
From: "Glen Sr" <ghazen1@...>
Sent: 9/7/2020 4:22:21 PM
Subject: Re: [QRPLabs] Select Button on Alignment QCX+ 20m

Richard. I have the same problem. I can raise and lower the audio noise also. Glen n8we
From: Richard M0AUW
Sent: Monday, September 7, 2020 1:11 PM
Subject: [QRPLabs] Select Button on Alignment QCX+ 20m

I’ve Just completed my 20m QCX+, it booted up fine showing 20m in the LCD, but when I went to press the select button to get Preset nothing happens. The LCD is working and showing the correct freq and when pressing the other buttons, I get a reaction. So, it seems to be just the select button. If the LCD is working could it be a problem with the 328 microcontroller?

I have checked R44 and R45 and searched the whole board for any bad solder joints, especially the button joints, all seems OK. Any ideas?


Many thanks Richard M0AUW


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