Raspberry Pi 7inch Touchscreen not working

[BIGD53]

Hello,

I have recently purchased a raspberry pi 7inch touchscreen. It was working fine yesterday but today when I plug it in it shows grey-black lines then it goes completely black. The red power light does not come on when the pi is plugged into the screen. I have my pi wired via GPIO pins and a DSI ribbon cable.

Thanks
P.S. - I am using a RPI 3 model B

[DougieLawson]

Pull the ribbon cable and re-seat it at both ends.

[BIGD53]

Thank you. I have tried this on multiple occasions already and found that I needed a new cable. So I have a new cable and I have re-seated it multiple times. I don't think the cable is a problem anymore. Could the screen need a firmware update or something of the sort?

[DougieLawson]

Get a copy of Raspbian, Etcher and a fresh new SDCard.
Try booting that.

[BIGD53]

I will try this tonight. Thanks. I'm not sure if it is the problem though because the green light comes on which means it registers the sd card. I have also accessed my pi via hdmi and it worked fine.

[DougieLawson]

Before you attempt to diagnose ANY hardware anomaly you need to be sure the software/firmware is working. Getting a fresh copy of Raspbian is a way to ensure that.

[BIGD53]

Got it. I am currently ordering a micro sd card on Amazon. I will test the new rasbian soon.

[BIGD53]

I have officially reinstalled rasbian on my pi and I have completely set it up. When I plug in the screen I still get the same result. The red light goes out and a lighting bolt appears on the hdmi screen I have hooked up.

[DougieLawson]

If you have an active 7" touch screen you can't have an active HDMI display. It's one or the other with the standard display drivers.

[BIGD53]

I unattached the hdmi cable and the screen comes on but it is white with vertical grey lines.

[gkaiseril]

I have a Pi 3B+ attached to the 7 inch touch screen. the only time I get the gray lines is with Noobs booting and Noobs booting the selected OS. My screen does not work if I switch the pins the power jumpers are connected to. Make sure you are only using the Gnd and the 5 vdc pins on the lcd screen and the Pi's GPIO pins. It is also possible to power the Pi and the touch screen using the power micro USB ports and two power supplies or one power supply and a micro USB Y adapter.

[BIGD53]

I have made sure the cables are connected to the right gpio pins on both the pi and the screen. When I tried supplying the screen and he pi with power the pi seems to boot fine but the screen becomes very hot and it smells like it might be burning.

[doctazz]

Like the poster above me, I also have a Pi 3B+ with a 7 inch touch screen, V1.1 from PRC. I don't use the GPIO pins for power. Instead, I use a 5V/2A USB adapter, so I don't have the burning smell issue.

(The poster above me may need to run an adapter for the Pi 3B+ with more amps, 2.5A at least.)

Is there some kind of firmware update needed for the touch screen? I tested this with two micro SD cards I specifically run for the 3B+. Each time, I got nothing but a black screen. I can get to the console only, minimal version of Raspbian on both cards via the 7 inch screen.

I'm typing this right now on the Pi 3B+ with a HDMI TV, using the card with the experimental install (not that it matters, but anyway...).

To add: I have the original Pi 3, and the 7 inch touch screen works there without any issues.

[doctazz]

Never mind... for some reason, I can't use the longer ribbon cable I bought to use with the Pi 3B+. I was hoping I could keep the 3B+ in a case that has a fan. Had to revert to taking it out of the case, attaching the display to the 3B+ with the original shorter cable, and then screwing the 3B+ to the back of the display.

In any case, not a big deal for me. My 3B+ has heatsinks on the CPU, and on the other chip installed on the same side (I think that's the GPU).

EDIT: Neither of the standard GL drivers work with the screen, at least on my 3B+.

[rpdom]

My 3B+ has heatsinks on the CPU, and on the other chip installed on the same side (I think that's the GPU).

What you call the CPU is actually the GPU and the CPUs.
The chip you thought was the GPU is the USB Hub and Ethernet controller.