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TFT LCD backlight not turning on (order no: 2388265-67452373
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TFT LCD backlight not turning on (order no: 2388265-67452373

by orangerd on Thu Oct 22, 2020 12:24 pm

Hi,

I just purchased two 1.54" 240x240 Wide Angle TFT LCD displays, but one of the displays doesn't seem to be powering up. The backlight on it isn't turning on, and I also couldn't get anything to display on it.

I tried switching around the cables, but no luck. Is there something I can do to debug further? Thanks in advance!
Attachments
PXL_20201022_062218161.jpg
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PXL_20201022_062229508.jpg
PXL_20201022_062229508.jpg (185.05 KiB) Viewed 252 times
PXL_20201022_063150434.jpg
PXL_20201022_063150434.jpg (138.91 KiB) Viewed 252 times

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Re: TFT LCD backlight not turning on (order no: 2388265-6745

by franklin97355 on Thu Oct 22, 2020 1:00 pm

By switching cables do you mean you swapped the working cable with the non-working display? (unplug the working cable from the working display and plug it into the non-working display)

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Re: TFT LCD backlight not turning on (order no: 2388265-6745

by orangerd on Thu Oct 22, 2020 3:34 pm

Yes, the working TFT is still fine on the other cable, so it's definitely not a cable issue AFAICT.

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Re: TFT LCD backlight not turning on (order no: 2388265-6745

by orangerd on Tue Oct 27, 2020 12:54 pm

Is there anything else I can try?

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Re: TFT LCD backlight not turning on (order no: 2388265-6745

by orangerd on Fri Oct 30, 2020 7:08 pm

Ping?

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Re: TFT LCD backlight not turning on (order no: 2388265-6745

by adafruit_support_carter on Mon Nov 02, 2020 2:56 pm

Please post another photo better showing the soldering on the problematic TFT.

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Re: TFT LCD backlight not turning on (order no: 2388265-6745

by orangerd on Fri Nov 06, 2020 4:13 am

Thanks, attached 2 photos but please let me know if you need other angles.
Attachments
PXL_20201106_080100777.jpg
PXL_20201106_080100777.jpg (82.27 KiB) Viewed 172 times
PXL_20201106_080053986.jpg
PXL_20201106_080053986.jpg (93.35 KiB) Viewed 172 times

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Re: TFT LCD backlight not turning on (order no: 2388265-6745

by adafruit_support_carter on Fri Nov 06, 2020 1:11 pm

Thanks. It's a little hard to fully see from that angle. But it could be a soldering issue. Some of the soldering in the other photos looks potentially problematic. Since you are able to see the issue move with the TFT, focusing on the soldering on the TFT itself seems like the best place to start.

See here for reference:
https://learn.adafruit.com/adafruit-gui ... n-problems
and examine all your pins and make sure they are good. If any look cold or under soldered, go back with your iron and try reflowing them.

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Re: TFT LCD backlight not turning on (order no: 2388265-6745

by orangerd on Sat Nov 14, 2020 3:10 pm

Thanks, I tried reflowing some of the solder, and also checked each pin with a multimeter to ensure they're not touching the next pin. Still, the backlight doesn't turn on, and nothing shows on screen. Is there anything else I can try?

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Re: TFT LCD backlight not turning on (order no: 2388265-6745

by adafruit_support_carter on Sat Nov 14, 2020 3:26 pm

Please post a photo of the back side of the problematic display, similar to this one:
https://cdn-shop.adafruit.com/970x728/3787-10.jpg

There are a few things we can check there.

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Re: TFT LCD backlight not turning on (order no: 2388265-6745

by orangerd on Tue Nov 24, 2020 1:12 am

Thanks (and sorry for the late reply - didn't notice there was an update here). I posted some more pictures of the problematic TFT. Please let me know if there should be other angles.
Attachments
PXL_20201124_050756162.jpg
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PXL_20201124_050735958.jpg
PXL_20201124_050735958.jpg (277.2 KiB) Viewed 108 times
PXL_20201124_050734035.jpg
PXL_20201124_050734035.jpg (316.17 KiB) Viewed 108 times

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Re: TFT LCD backlight not turning on (order no: 2388265-6745

by adafruit_support_carter on Tue Nov 24, 2020 2:41 pm

Thanks. It looks there's a chance the ribbon cable is not fully seated into the mating connector. Note how much of the black part of the ribbon cable is visible. You can use your other display as a reference, or checkout the product photo here:
https://cdn-shop.adafruit.com/1200x900/3787-10.jpg

Try reseating it a little better and see if that helps at all. You'd slide the black plastic retainer clip outwards, push the ribbon cable in more, and the slide the plastic retained back in. If you need more details, let us know.

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Re: TFT LCD backlight not turning on (order no: 2388265-6745

by orangerd on Sun Nov 29, 2020 3:00 am

The ribbon cable from my working LCD actually looks pretty similar to the defective one (the one with the cables attached is the working LCD). I tried pushing the ribbon cable in a bit more, but no budge still.
Attachments
PXL_20201129_065726513.jpg
PXL_20201129_065726513.jpg (287.71 KiB) Viewed 63 times

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Re: TFT LCD backlight not turning on (order no: 2388265-6745

by adafruit_support_carter on Mon Nov 30, 2020 12:37 pm

Hmm. OK. Thanks for those photos. Agree, they both look the same. It was worth checking at least.

Looking back at your testing with swapped cables:
Yes, the working TFT is still fine on the other cable, so it's definitely not a cable issue AFAICT.

Did you leave the cables in the same place on the Bonnet? Or to put it another way - if you don't change anything other than move the working display from one location to the other - that display works OK in both locations?
(need to make sure it's not something on the Bonnet)

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Re: TFT LCD backlight not turning on (order no: 2388265-6745

by orangerd on Tue Dec 01, 2020 3:38 pm

I kept the cables on the bonnet as-is - the working display works on both sides of the bonnet. The faulty display doesn't work on either side of the bonnet, though.

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