# 7" Touchscreen backlight only dims (solved)

**URL:** <https://forums.pimoroni.com/t/7-touchscreen-backlight-only-dims-solved/12476>\
**Category:** Support\
**Created:** [December 17, 2019, 8:38am UTC](https://forums.pimoroni.com/t/7-touchscreen-backlight-only-dims-solved/12476 "2019-12-17T08:38:29Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![foxbow](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.pimoroni.com/foxbow/32/6198_2.png) [@foxbow](https://forums.pimoroni.com/u/foxbow)\
**Post date:** [December 17, 2019, 8:38am UTC](https://forums.pimoroni.com/t/7-touchscreen-backlight-only-dims-solved/12476/1 "2019-12-17T08:38:29Z")

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Hello,

my touchscreen works fine, I got the rotation properly for the case and touch works as expected, only the backlight can’t be dimmed below a certain point. All the following: DPMS force off, echo 1 \> /sys/class/backlight/rpi\_backlight/power and echo 0 \> /sys/class/backlight/rpi\_backlight/brightness only make the screen dim somewhat but it’s still pretty bright.

Running a loop to test the brightness levels made it look like ~75 sets the maximum brightness, everything above does not change a thing and everything below makes it go dimmer as expected. However to turn it off I would have to set the brightness to -180…

Any ideas what the reason could be? Everything else works as expected. And searching just returns topics leading to the above ways of controlling the backlight.

Edit: the control board has version 1.1 and the Raspberry is a Pi 3 Model B 1.2  
Edit2: kind of feels like a gate that should be pulled up is floating instead, but which?  
Edit3: Attaching external 5V makes it behave properly.