Hot speaker and dark screen, why? [SOLVED]

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#1

I had made up a MAKERBuino but the screen is too dark . With the volume in the lightest position, I can scarcely read characters. And the speaker is going hot.
I checked all parts and solders, but no mistake was found. What seems to wrong? What part of my MAKERBuino shall I check again?

#2

what do you mean by too dark? Do you see pixels but everything is black or almost, or backlight is dark?

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#3

The backlight is OK. I can see pixels but even “white” pixels are nearly black.

#4

I think a picture is necessary.

I don’t think this can be because of contrast adjustment because white pixels are supposed to be white, regardless of the contrast setting. You should check your solders, especially what’s connected to the screen and the microcontroller.

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#5

Thanks for advices.

image
image.jpeg1936Ă—2592 1.1 MB

This is the picture. The contrast adjustment is set as a brightest position.
I will check again soldering, and also that the MPU is correctly inserted into the socket.

#6

The contrast setting is too high: the middle square is supposed to be grey, and it is black. Try to adjust this first , and tell us how it goes.

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#7

@Mshige, I agree with @Tom, you need to adjust your contrast settings. Did you manage to do that?

I am not sure why the speaker is getting hot, I’ve never heard about that problem before. Please send us some photos of your MAKERbuino’s front and back side with the casing removed.

#8

Thanks for good advices. Now my MAKERBuino is working.
The display darkness is solved by adjusting it by buttons. It changed by moving right volume, so I had mistaken the volume is the adjusting point.
The speaker heat was caused by two solder bridges, mainly between the diode and the resistance of the speaker circuit (see right under of the code connections to the speaker). Two transistor pins seems to be bridged. See picture attached.
Removing bridging solder, the heat problem disappeared and I can hear sounds from my MAKERBuino. Thanks again for all commenters.

image
image.jpeg1936Ă—2592 1.3 MB

#9

Good to see the problem is solved.

This is an advice for everybody: ALWAYS check for solder bridges. There should NEVER be solder bridges. It creates short circuits. In the best case something doesn’t work, in the worst case something breaks.

There is one exception, sometimes some pads are meant to be solder-bridges (often called SN-something). These are made for configuring the PCB, and usually you have nothing to do with these (and it is the case with Makerbuino).

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