LCD power and high pitched noise

omgitsaheadcrab
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Re: LCD power and high pitched noise

Post by omgitsaheadcrab » Wed Feb 20, 2019 1:10 pm

I downloaded your latest software image (1.3.2) and copied it to two SD cards. No joy on either, assuming the images are good.

Turning on the board lights up all the LEDs but not the LCD backlight. Switching the board off takes a couple of seconds and then all the LEDs (except the battery charging ones) turn off - I assume this is the shutdown procedure working correctly now.

Attached are images of the working LEDs and how I've connected the screen, looks right to me :?

PS. the board gets very hot where it says BATT +/- in 1.jpg
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0.jpeg
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kite
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Re: LCD power and high pitched noise

Post by kite » Thu Feb 21, 2019 3:16 am

Ok cool, can you do the following:

1. Remove everything so that all you have connected is: CS + battery + power switch (so no LCD, CM3, or SD).
2. Power on
3. Measure with a multimeter the voltage from GND (black probe) to both sides of the big diode "D3" (which is under where the CM3 usually goes, next to the BL_OK LED). You are expecting to read ~3.9V on one side (battery voltage) and ~35V on the other.
4. Power off, plug the LCD in, power on, and repeat step #3. You are expecting to read ~3.9V on one side (battery voltage) and ~21V on the other.

Could you please let me know the voltage readings from those steps

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Re: LCD power and high pitched noise

Post by omgitsaheadcrab » Thu Feb 21, 2019 1:03 pm

With no screen I read 35.8V on one side and the other side jumps all over the shop, from 0V up to like 9V, but it's very quick.
With a screen attached I still read 35.8V on the one side and the other flashes between 15V and 0V.

The battery itself reads 3.94V.

EDIT: So I tried again and for every variation of screen/no screen and battery/battery+usb/usb I get 0V and 0.1-0.2V now. I've tried various spots for GND but can't seem to get it to give me the 35.8V it was showing earlier.. :/
I tried connecting everything again and PGOOD (and all the other LEDs) still comes on and the safe shutdown procedure still works.

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Re: LCD power and high pitched noise

Post by kite » Fri Feb 22, 2019 9:57 am

omgitsaheadcrab wrote:
Thu Feb 21, 2019 1:03 pm
With no screen I read 35.8V on one side and the other side jumps all over the shop, from 0V up to like 9V, but it's very quick.
With a screen attached I still read 35.8V on the one side and the other flashes between 15V and 0V.

The battery itself reads 3.94V.

EDIT: So I tried again and for every variation of screen/no screen and battery/battery+usb/usb I get 0V and 0.1-0.2V now. I've tried various spots for GND but can't seem to get it to give me the 35.8V it was showing earlier.. :/
I tried connecting everything again and PGOOD (and all the other LEDs) still comes on and the safe shutdown procedure still works.
Right ok, it sounds like the LCD itself is dead. Could you send me an email again with your address and I'll send you a replacement LCD and we'll try that!

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Re: LCD power and high pitched noise

Post by omgitsaheadcrab » Sat Mar 02, 2019 6:45 am

New LCD arrived this morning, everything works well now and all tests pass. It seems to loop through and never quite stop, much like the Circuit Gem (which is was working well btw*), so I assume it works. The shutdown procedure works fine either way.

Will build this weekend, thanks for all the support kite!

* spoke too soon.. gem was fine and happy and then I installed it into its case and now I'm not even getting the pgood led or a backlight. I'll have to check my gpio soldering.. but that's for another thread!

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Re: LCD power and high pitched noise

Post by kite » Mon Mar 04, 2019 4:54 am

omgitsaheadcrab wrote:
Sat Mar 02, 2019 6:45 am
New LCD arrived this morning, everything works well now and all tests pass. It seems to loop through and never quite stop, much like the Circuit Gem (which is was working well btw*), so I assume it works. The shutdown procedure works fine either way.

Will build this weekend, thanks for all the support kite!

* spoke too soon.. gem was fine and happy and then I installed it into its case and now I'm not even getting the pgood led or a backlight. I'll have to check my gpio soldering.. but that's for another thread!
No problem :) glad we got to the bottom of it!

As for the Gem, send me a message (or link to the thread if i managed to overlook it) and I can help out, but yeah check soldering mainly on the power (3v3 and 5v/vcc), GND (GNDs are the HARDEST to solder, so def check that these are good connections) and the PGOOD pin obviously :)

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