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QCX mini, Encoder and buttons stop working

 

Hello -?
Curious issue with my 20 meter QCX Mini.
On power-up, everything works fine.
After a few minutes I can't adjust the tuning rate with the encoder and the two buttons are non-functional.
Turn the unit off, restart it, everything is okay again but after a few minutes the issue repeats.
Any ideas? Something overheating? Buggy software?
Any help appreciated.
Dan N3DTF
 

I should also mention that I'm able to change the frequency with the encoder when my issue occurs.
 

Dan, good description of the symptoms. I think you have an intermittent connection, probably an old solder joint that was good enough early on but has degenerated over time. Specifically it is somewhere in the line labeled “buttons” between the little controls board and pin 26 of the microcontroller. Most likely it is one of the pin connections on the little board or the main board, identified as pin 6 of JP100 on the little controls board. The short pins that connect to the little board were a bit too short to come all the way through the holes and required more heat to get good solder penetration down around the top of the pin. Take a look there first and reheat the connection even if it looks ok.?

Good luck. 73….Ron

On Sat, Aug 17, 2024 at 05:29 Dan Finegan via <dantomfin=[email protected]> wrote:
I should also mention that I'm able to change the frequency with the encoder when my issue occurs.
 

One other?thing Dan. The 5v point on JP100 is pin 8 and that one can also cause your issue. Make sure all the pins, especially the ones on the top of the little board are well soldered. .. Ron


On Sat, Aug 17, 2024 at 6:26?AM Ronald Taylor via <wa7gil=[email protected]> wrote:
Dan, good description of the symptoms. I think you have an intermittent connection, probably an old solder joint that was good enough early on but has degenerated over time. Specifically it is somewhere in the line labeled “buttons” between the little controls board and pin 26 of the microcontroller. Most likely it is one of the pin connections on the little board or the main board, identified as pin 6 of JP100 on the little controls board. The short pins that connect to the little board were a bit too short to come all the way through the holes and required more heat to get good solder penetration down around the top of the pin. Take a look there first and reheat the connection even if it looks ok.?

Good luck. 73….Ron

On Sat, Aug 17, 2024 at 05:29 Dan Finegan via <dantomfin=[email protected]> wrote:
I should also mention that I'm able to change the frequency with the encoder when my issue occurs.
 

Ron, thank you your replies.?
I'll have a try with your suggestions but waiting on a smaller soldering iron. Most of my soldering experience is with vintage radios with point-to-point wiring.?
73 -?
Dan N3DTF
 

I finally took the QCX Mini apart but I couldn't identify any of the landmarks that were suggested to check. In other words, I couldn't locate the "buttons" label on the controls board or the JP100 point.
Am I missing something obvious?
Any help is greatly appreciated.
Thanks and 73 -
Dan N3DTF
?
 

I should have been more?specific Dan. The labeling is not on the board. You have to look at the schematic diagram to identify those points. But, in the mean time, if you got your new small soldering iron you were waiting for, you need to reheat the joints on top of the little controls board that are the 2X4 pin header connections. Apply heat until solder melts on them then hold it there a few more seconds before removing the iron. Redo all 8 pins. Then turn the radio over and reheat the equivalent 8 pins on the bottom of the main board that are the pins of the 2X8 socket that the controls board plugs into. Let us know how it goes.?

73…搁辞苍?

On Fri, Nov 15, 2024 at 06:48 Dan Finegan via <dantomfin=[email protected]> wrote:
I finally took the QCX Mini apart but I couldn't identify any of the landmarks that were suggested to check. In other words, I couldn't locate the "buttons" label on the controls board or the JP100 point.
Am I missing something obvious?
Any help is greatly appreciated.
Thanks and 73 -
Dan N3DTF
?
 

Reflowing the solder on the pin headers and the pins didn't seem to help.
Here's another possible clue:
When the encoder stops changing the tuning rate, if I turn it while pressing down firmly ON THE SKIRT on the knob, the function is restored.
Pressing directly on the top of the knob has no effect.
Makes me wonder if the encoder is funky.
Of course, any further suggestions are greatly appreciated.
73-?
Dan N3DTF
 

Using mechanical pressure like that to restore functionality suggests a poor/cold connection somewhere on the controls board - likely one of the encoder pins, or maybe one of the SMD resistors nearby.? Flexing the board causes it to temporarily restore the connection.
 

Dan, if you refer to the schematic you will?see that all the buttons, including the switch on the encoder, all share one connection to the microcontroller pin 26. The encoder itself labeled ROT A and ROT B on the schematic go to separate pins on the microcontroller. Since the encoder works and all the buttons are flaky, then the only commonality is either the "buttons" connection somewhere between the controls board and pin 26 of the microcontroller, or the Vcc (5v) connection from the main board to the controls board. Pressure on the controls board, via the skirt of the encoder knob is making the flaky connection come back. You can check continuity from the bottom of the main board to the top of the controls board (with power off). Check each of those 8 connections for continuity.?

Ron

On Fri, Nov 15, 2024 at 7:44?PM Stan Dye via <standye=[email protected]> wrote:
Using mechanical pressure like that to restore functionality suggests a poor/cold connection somewhere on the controls board - likely one of the encoder pins, or maybe one of the SMD resistors nearby.? Flexing the board causes it to temporarily restore the connection.
 

Dan,
?
did you find the issue to your culprit? Read Ronald Taylor’s recent thread about “QCX buttons stuck”. ?I replied to his thread too. ?I was having the same exact issue. ?It is indeed a firmware bug. ?

After selecting the keyer speed and then pressing the encoder button to exit the keyer speed menu that is when I was having that issue. ?The encoder button is not the correct button to exit that menu. I have to remind myself because I created a bad habit of using it since the encoder button allows me to exit that menu but then causing other issues.
?
Before reading Ronald’s post I discovered the issue and I am glad he posted it because it confirmed my “discovery” and gave me hope that I can build another QRP lab rig.

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