Backlight is incredibly dim

[larry]

I left my Pandora on the plane on my way to FOSDEM


The airline found it, it was no big deal--I picked it up from Lost & Found today


But now the screen is incredibly dim


If I go into a dark room and hold the screen at an angle, I can barely read the screen. The Pandora is working fine otherwise; it boots into xfce, and I can run programs. I tried both my batteries, I plugged it into the wall, nothing helps. I tried the Fn-U and Fn-I backlight buttons; I can make it even darker, but I can't make it brighter. I also tried the Settings | LCD dialog, that didn't fix it either.


I have no idea what happened to it between it falling out of my bag and me picking it up today. The memory cards are both fine, so it couldn't have been too traumatic.


Any ideas beyond "send it back"?


Thanks,

 

[Mr_Loon]

Is the screen dim during the boot process?


Is the screen dim at all hinge angles?


My best guess is that you have a loose / broken LCD cable, but if you've tried everything else then a reflash would not hurt.

 

[larry]

The screen is dim during the boot process. The screen is dim at all hinge angles.


I just reflashed, leaping from Hotfix 5 to Hotfix 7. It was ticklish reflashing without a working screen, but I swung it. And I swear the screen is sliiiiightly brighter now! But it's hardly fixed.


Thanks just the same, Professor Yaffle!

 

[WizardStan]

The only trick left in the bag I can think of is to remove the battery and leave it out for 20 minutes or so, give all the hardware a chance completely shut down and reset.

 

[larry]

Still dim, sadly.

 

[double7]

If it fell down it could be anything. From power transformation parts, the backlight power inverter, the LCD cable or the backlight itself. As a visitor of FOSDEM there's a chance you like to do it yourself. ;-)


There is a good guide how to replace the LCD cable, which is useful for opening and closing the pandora too. But it's gone? No, here it is:

Spoiler

https://www.youtube.com/embed/l8GfjAsbmK8?feature=oembed

Just try to disconnect and reconnect the LCD cable. If that doesn't work you're done.


If you are a hardware hacker, there are the manuals http://pandorawiki.o...ardware_hacking for the pandora and the screen. If you're not you need to contact ED for repair.

 

[WizardStan]

Open a terminal, and on the command line

cat /sys/class/backlight/twl4030-pwm0-bl/brightness

sudo su

<enter password>

echo 50 > /sys/class/backlight/twl4030-pwm0-bl/brightness

exit

The first command tells us what the brightness was set at, the second makes you super user so you can then modify that value, setting it to 50, the maximum value.


If it was already 50 then it probably won't help. The fact that it is dim even after the power down suggests it's a hardware fault though.

 

[EvilDragon]

Is the backlight on at all?

 

[larry]

If you are a hardware hacker, [...]

I'm not a hardware hacker.

Open a terminal, and on the command line

cat /sys/class/backlight/twl4030-pwm0-bl/brightness

sudo su

<enter password>

echo 50 > /sys/class/backlight/twl4030-pwm0-bl/brightness

exit

It was actually at 54. (That's the value reported by the Settings | LCD Settings dialog too.)


I changed it to 49, just to be sure it was within the normally allowed range. Didn't seem to help.

Is the backlight on at all?

Yes, unless there's something else that would make the screen light up. If I take it into a totally dark room, the screen is very obviously producing some light.


ED, do you agree with double7 that I should try reseating the LCD cable? I'm traveling right now, so I don't have all my tools, but I could probably manage to do that.


Failing that, where should I send it for repair? I bet I should do that soon, before 250 freshly-built boards parachute into your lives

 

[larry]

Okay. I got brave and re-seated the LCD cable. No change, screen is still dim.


ED, could you send me your address so I can ship you my Pandora for repair? Note that I'm in Dublin today and fly back to the US tomorrow morning... if I could send it today then I think it'd get there faster.

 

[EvilDragon]

Ship it to:


OpenPandora GmbH


Schäffbräustr. 11


85049 Ingolstadt


Germany


Sounds like either the powering circuit for the backlight broke or the inverter inside the LCD itself.