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QCX Mini Displaying //???/??/

 

New QCX Mini (20m) build and everything seems to be working except for the screen will go blank and/or display a mix of /'s and ?'s after the initial boot screen. Boot screen always displays both lines of text and then roughly half the time I get the random mix of ?//? on just the top line or a single black character on the top right. The other half of the time the screen displays the frequency on the top line and I'll get a few button presses before it again falls back to the ?/???? junk. Pushing any of the buttons updates the line but never goes back to anything other than a single black box or the junk characters.
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I've inspected the board pretty closely, re soldered pretty much everything on the board at this point, and checked continuity between the screen and IC2 pins which all seems to check out. I've also checked the voltage on all the screen pins with a multimeter and while they aren't exactly what is in the build guide they seem to be within the expected operating range. That about hits the limit of what I know to do for troubleshooting, any advice would be more than welcome.

 

Hi Matt. The issue still really sounds like a loose connection somewhere. Maybe since you are sure your soldering is OK you could try giving a gentle twist to the tabs on the back side of the LCD module to tighten them up. The one that you had to bend per the instructions may need a tightening twist to it as well. Connections inside between the LCD unit and the backplane circuit are just contacts that need to stay reasonably tight. In the unlikely event that it's something glitching in the firmware, then a factory reset might fix it. If you don't have meaningful intelligence on the screen long enough to get through that process you could always do it by counting button pushes and rotary encoder clicks. I actually wrote down the "blind" procedure to do a reset. If you need that, let me know. Good luck ..73 ... Ron


On Tue, Apr 15, 2025 at 8:50?PM Matt via <code08=[email protected]> wrote:
New QCX Mini (20m) build and everything seems to be working except for the screen will go blank and/or display a mix of /'s and ?'s after the initial boot screen. Boot screen always displays both lines of text and then roughly half the time I get the random mix of ?//? on just the top line or a single black character on the top right. The other half of the time the screen displays the frequency on the top line and I'll get a few button presses before it again falls back to the ?/???? junk. Pushing any of the buttons updates the line but never goes back to anything other than a single black box or the junk characters.
?
I've inspected the board pretty closely, re soldered pretty much everything on the board at this point, and checked continuity between the screen and IC2 pins which all seems to check out. I've also checked the voltage on all the screen pins with a multimeter and while they aren't exactly what is in the build guide they seem to be within the expected operating range. That about hits the limit of what I know to do for troubleshooting, any advice would be more than welcome.

 

Would definitely appreciate a blind reset procedure.
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I agree it seems like a loose connection but there doesn't seem to be any shorts I can find and all the pins have continuity between the processor and screen's board. The only thing I can think is there is something in between which is dropping some signal so the screen isn't getting the proper 1's and 0's but I'm not sure how to test for that. What's really getting me is all the troubleshooting I'm seeing is for a screen that doesn't work at all, mine definitely is working and I get the start up text then it's only when characters try to change on screen that it starts bugging out. I'm getting to the point where I might directly wire the screen to the processor pins and bypass all the board/jumpers but that kind of kills the "mini" form factor :D
 

Have you checked at the processor pins?? A tiny bit of wire or solder flake could be bridging a couple of the processor pins that drive the display?
 

Here's a procedure to do a factory reset on a QCX when you don't have a working display. Count carefully:

Long press left button
Turn tuning encoder counterclockwise (CCW) 4 clicks
Short press left button
Turn tuning encoder CCW 1 click
short press left button
Turn tuning encoder Clockwise 17 clicks
Short press left button

Good luck .. 73 .. .Ron


On Wed, Apr 16, 2025 at 5:26?PM Stan Dye via <standye=[email protected]> wrote:
Have you checked at the processor pins?? A tiny bit of wire or solder flake could be bridging a couple of the processor pins that drive the display?

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