Booting with no screen attached

[atmu5fear]

I want to be able to boot my old s3, out of the housing it came in, eg no screen, no mid frame, no cover. Just the mother board. I can boot it with every thing else disconected, and I can have it running, and unplug the screen and it stays running just fine. But if you try to reboot it it just won't. The screen is connected via a ribbon from the screen housing which not only feeds the Screen but also the touch digitizer, the home, back, and menu buttons, the microphone and the vibrator pod. I can have the mother board completely out of the case and running after unplugging this single ribbon, but I cant boot it without the ribbon plugged to the mother board. This is for a project in which the device is remotely accessed from another device, and the screen and glass and hoousing only adds unnecessary weight. Anyone know how to fool the motherboard into thinking the ribbon is connected? Or at least provide some insight about why it can run just fine without it, but can't boot unless it's plugged in?

Thanks

 

[mydian]

This is just a guess, but perhaps the boot process checks various hardware components to make sure they're functioning and since the screen is missing it won't boot.

 

[atmu5fear]

This is just a guess, but perhaps the boot process checks various hardware components to make sure they're functioning and since the screen is missing it won't boot.

Yup I was thinking the same thing. But since it wont power on at all, I think its simpler than that. Like the ribbon completes a circuit or something. Not like a PC that will power on and not boot up after hardware checks, since if that was the case the phone would still turn on and not boot past splash. Likewise, if the lcd or touch screen digitizer is broken (not functioning) the phone will still turned as long as its attached. I was thinking of cutting the rippon and leaving it plugged in, but if that doesnt work ive officially bricked the device and need to start buying parts to continue my project. I'm going to try and remove the glass and lcd and other components from the frame itself, in a manner that allows them to be reinstalled if it doesn't work

 

[svim]

The screen ribbon cable and the digitizer ribbon cable appear to be separate items. (steps 18 & 19)
https://www.ifixit.com/Guide/Samsung+Galaxy+S+III+Motherboard+Replacement/12696
Also, here's a repair/schematics manual that might help indicate which pins to short out to see if that S3 will boot without the connector? (LCD starts on pg. 77, touch screen on pg. 80)
http://www.s-manuals.com/pdf/phone/samsung/samsung_gt-i9300_service_manual_r1.0.pdf

 

[mydian]

Yup I was thinking the same thing. But since it wont power on at all, I think its simpler than that. Like the ribbon completes a circuit or something. Not like a PC that will power on and not boot up after hardware checks, since if that was the case the phone would still turn on and not boot past splash. Likewise, if the lcd or touch screen digitizer is broken (not functioning) the phone will still turned as long as its attached. I was thinking of cutting the rippon and leaving it plugged in, but if that doesnt work ive officially bricked the device and need to start buying parts to continue my project. I'm going to try and remove the glass and lcd and other components from the frame itself, in a manner that allows them to be reinstalled if it doesn't work

Good point. Good luck with your project!

 

[atmu5fear]

The screen ribbon cable and the digitizer ribbon cable appear to be separate items. (steps 18 & 19)
https://www.ifixit.com/Guide/Samsung+Galaxy+S+III+Motherboard+Replacement/12696
Also, here's a repair/schematics manual that might help indicate which pins to short out to see if that S3 will boot without the connector? (LCD starts on pg. 77, touch screen on pg. 80)
http://www.s-manuals.com/pdf/phone/samsung/samsung_gt-i9300_service_manual_r1.0.pdf

Awesome thanks for both those. As far as I can tell, #18 of that guide is not the digitizer. That ribbon feeds the LED above the screen, and the volume rocker. That service manual probably has the answers to all my questions, once my shabby data connection lets me download it (waayyy up north in the middle of nowhere, im surpised I have any coverage at all!) Thanks a ton.

Good point. Good luck with your project!

Thanks