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3.5 TFT ( HXD8357D ) Randomly...Died?
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3.5 TFT ( HXD8357D ) Randomly...Died?

by Vexser on Sun Mar 26, 2017 6:28 am

Hey. Wondering if I had a defected product or what.

https://www.adafruit.com/products/2050

I bought this screen awhile ago. and every time it boots up ( on 5V ) it always made high pitch noises. After ~5 minutes this high pitch nose slowly fades away. I noticed on the board, the large black item ( Cant tell if its a diode..core.. nothing labeled on it ) right next to the print saying "GC-D1 94V" right near the chips, was making that noise. I noticed if I took a rod and pushed down on it lightly, it would change the characteristics of the noise. The screen always kinda had a bit of random unstable looking lighting but I figured it was just generically expected due to being a TFT.

I've ran this setup on a Teensy for awhile now. Few weeks of short-duration testing for design. Today I finally took it out for a long run. Lasted 2 hours fine, but then suddenly the screen went black. I figured the battery died ( red light on the charger ) but recently learned its drawing a bit of current. The Teensy is still operating, the status light is working as per-usual and serial monitor confirms normal operation. However, that ( diode? ) no longer squeels. instead. its getting extremely hot.

So..basically something failed due to a long duration run. My guess is whatever was squeeling, was faulty from the start, and finally gave out. Wiring is proper. Nothing shows damage ( no pinched wires, no melted wires, etc ) looks fine. Bit annoyed because I've been using this screen with no problems for a couple weeks..then suddenly it just fails. No changes made, just longer run time.

So..yeah. Posting to see if anyone can say "Oh i had that happen before" and point me in a direction. Kinda doubting I can get a replacement without basically just buying another one and saying "Oh it happens too bad, buy another?"

http://i.imgur.com/9FC0ilq.png -- Part that use to squeel, but now gets hot
http://i.imgur.com/ITZATC3.jpg -- Misc use of the LCD, trying to mimic the one currently in the car

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Re: 3.5 TFT ( HXD8357D ) Randomly...Died?

by adafruit_support_rick on Sun Mar 26, 2017 8:26 am

Not sure what part that is. Might be an inductor.
How long have you had this display? Our replacement warranty period is 30 days.

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Re: 3.5 TFT ( HXD8357D ) Randomly...Died?

by Vexser on Sun Mar 26, 2017 11:00 pm

adafruit_support_rick wrote:Not sure what part that is. Might be an inductor.
How long have you had this display? Our replacement warranty period is 30 days.


Well. Now things get interesting. Will post my findings and maybe someone can understand it.

When I disconnected everything and only powered the screen via 5V, the backlight turns on and the inductor doesnt get hot. So I reconnected CLK/MISO/MOSI/CS/DC, and the screen flicks on for a second ( backlight ) then goes black and squeels -- super hot inductor. I disconnected the DC wire, and powered it on. The screen is blank-white, no problems. While still on, i re-connected the DC wire and re-flashed my chip teensy 3.5 and the screen displayed the image, inverted. Leaving everything as-is, I disconnected ALL power, and re-powered everything, and now the screen displays everything fine.

So....Magically the screen is now working. Sounds to me like it got 'stuck' in some fluke, that was literally shorting it out, thankfully nothing exploded ( inductor has a hole in the case though ), and by disconnecting the SPI, boot cycling it, and re-connecting the SPI, re-boot cycling it, it works now. Why? I saw on the tutorial page "You do not need to connect the RST or other pins" so I never had the RST pin connected to anything. My only guess is thats gotta be what put this in a stuck position.

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Re: 3.5 TFT ( HXD8357D ) Randomly...Died?

by adafruit_support_rick on Mon Mar 27, 2017 9:06 am

Removing power should reset it. Don't think the reset line is the problem. Holes in components aren't a good thing. You might want to think about replacing it.

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Re: 3.5 TFT ( HXD8357D ) Randomly...Died?

by SAM1989 on Wed Aug 09, 2017 1:53 pm

Hi,
I'm having a similar issue but without the inductor heating up. My issue is the high frequency squeaking sound that this screen makes.
I'm not sure which component is making the sound, but when i try to touch the components in the back and press a little bit it seems to reduce the noise.
I didn't have this issue with just one screen. I actually ordered like 10 of them, and the first two or three that I have used so far have this issue. Usually these screens are silent at the beginning, but after a few uses they start making the noise. ( I haven't used the rest of the screen to see if the are working, but the first couple that I opened have this issue, and another one that I bought a few months ago also has the issue)
I wonder if ADAfruit can try them out to see if they have the same issue. Mabe the batch I got is defective and needs returning. Mabe there is something wrong in the circuitry.
Thanks

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Re: 3.5 TFT ( HXD8357D ) Randomly...Died?

by adafruit_support_rick on Thu Aug 10, 2017 8:52 am

That's going to be the high-voltage boost for the backlight. Sometimes they oscillate a bit and make that noise. It's not defective - that's just the way they are.

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Re: 3.5 TFT ( HXD8357D ) Randomly...Died?

by adafruit2 on Thu Aug 10, 2017 10:36 am

you can use some foam tape or hot glue around the boost converter, sometimes that reduces the noise!

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