New HM Button Issue?


 

John_W

New member
Got the order today (4.3) and got it put together and everything seems ok. But I am having a weird button issue. (although I am fairly sure its not the actual button)

I fully suspect this is something to do with Me and not with the unit, just wondering if there is anything you can think of to check.

For example, currently when it boots, its on the main screen. When I click the right button, I see the next screen, then it quickly returns back to the main screen. If I hold the RT button, I see it scroll through the menu, but when I let go, I get returned back to the main screen.



Any thoughts, on what I should check?


EDIT: Wanted to add a video showing

https://photos.app.goo.gl/BCjM5vMuGLgtTZ6S8

Also, starting to think it MAY be a component issue? It seems if I leave it unplugged for a bit, when I plug it in, it will work as expected for a short time?
 
Last edited:
I'll post what I sent to you in the email just for posterity
Hi John, sounds like you're really close!
What usually manifests itself as floating button voltage is usually a bad connection on the 1k resistor on the base board next to the right LCD pinheader. It's the pulldown and forms half the resistor divider that makes the button voltage. I'd hit the legs of that with the soldering iron real good to make sure you've got a good ground connection (the one furthest from the microcontroller).

You should also be able to measure the resistance with no button board connected and it should read as 1k between GND and where the BTN pin comes up on the LCD header (measure from the bottom of the base board with no Pi or LCD board attached). You can also try checking the voltage between BTN and GND on the LCD/Button board. It should be 0V with nothing pressed, no variation. Then for each button, hold it and see if you get a solid voltage on the BTN pin. If it is affecting all the buttons then it is either that 1k resistor or the connection between the BTN LCD header pin and the BTN pin on the microcontroller so that's where my money is.

But watching the video it seems like just the left button is having a problem maybe? I'd definitely check the 1k resistor, but also check the no-button-pressed voltage on the BTN pin of the LCD header because it looks to have voltage at idle. The "left" voltage is the lowest of the lot at 0.543V, but triggers between 0.259V and 0.764V so it seems you've got that much voltage floating on the rail.
 
Yeah, so as I mentioned in my most recent email, the problem appears after the unit is powered on for 30-90 seconds.


While the 1K on the base board appears fine, I do have an extra 1k laying round from my parts bin i can try and replace it?

Here are some ohms testing I have done

LCD Board - No power



BTN/GN Black lead on GND

All Buttons Released (none depressed)
200k Scale 38.5 ohms

Up Button Depressed
200k Scale 5.3

Down Button Depressed
200k Scale 6.3

Left Button Depressed
200k Scale 10

Right Button Depressed
200k Scale 4.9


Tested the BTN pin to all buttons, and 0 ohms

Here is some voltage test

LCD/Button Board with 12v supplied

GND/BTN - about .4 volts with no buttons depressed

Any other test you can think of? Anything seem odd?
 
I think I am finding out that R9 (resistor for my Left Button) maybe bad/damanaged/poorly soldered.

I have removed the resistor from the circuit (for testing) and will report back
 
Update:

Can confirm, with the R9 Resistor removed the unit functions normally (without the use of the left button)

When I replace the resistor with a replacement, back to square 1. Bad button maybe?
 
Well, while the button tested fine, I went to remove it, and got it half way out and said F it, let me test again, sure enough its working now. I pushed the button back in, re solder, and will report if there are any issues.

Lesson - Even if it ohms out, verify the solder joint i guess?
 

 

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