My backlight is on full _all_ the time - even when blanked
 

I dont understand why....

- backlight level controls do not error - but do absolutely nothing!
- even when when the screen is locked... the backlight is on!

Yesterday for a short while, the backlight was flickering full/lower seemingly randomly for about 20 minutes. I put it down to a low battery since reboot made no difference but after reboot the battery was very low (red icon) and after putting in a fresh battery the flickering stopped. But it stopped with the BL on full and uncontrollable. Reboots make no difference.

Any ideas?

[edit]
Messing with /sys/class/backlight/acx565akm/brightness and /sys/class/backlight/acx565akm/bl_power make no difference...

[edit 2]
I remember doing and apt-get upgrade with CSSU enabled - these got updated yesterday:

-rw-r--r-- 1 root root 427 Jul 3 11:56 katana.list
-rw-r--r-- 1 root root 433 Jul 3 11:59 libqt4-core.list
-rw-r--r-- 1 root root 657 Jul 3 11:59 libqt4-gui.list
-rw-r--r-- 1 root root 419 Jul 3 12:05 easy-chroot.list
-rw-r--r-- 1 root root 14539 Jul 3 12:05 easy-deb-chroot.list
-rw-r--r-- 1 root root 159 Jul 3 23:16 libespeak.list
-rw-r--r-- 1 root root 1332 Jul 3 23:16 marble.list
-rw-r--r-- 1 root root 7567 Jul 3 23:16 espeak-data.list
-rw-r--r-- 1 root root 1120 Jul 3 23:16 marble-plugins.list
-rw-r--r-- 1 root root 27678 Jul 3 23:17 marble-data.list
-rw-r--r-- 1 root root 245 Jul 3 23:17 libmarble.list
-rw-r--r-- 1 root root 23648 Jul 3 23:17 marble-maps.list
-rw-r--r-- 1 root root 8195 Jul 3 23:17 xournal.list
-rw-r--r-- 1 root root 304 Jul 3 23:17 file.list
-rw-r--r-- 1 root root 4836 Jul 3 23:17 advanced-interface-switcher.list
-rw-r--r-- 1 root root 2848 Jul 3 23:18 advanced-power-monitor.list
-rw-r--r-- 1 root root 420 Jul 3 23:18 backupmenu.list
-rw-r--r-- 1 root root 306 Jul 3 23:18 busybox-power.list
-rw-r--r-- 1 root root 8489 Jul 3 23:18 cacheme.list
-rw-r--r-- 1 root root 476 Jul 3 23:18 clipman.list
-rw-r--r-- 1 root root 11129 Jul 3 23:19 hivemind.list
-rw-r--r-- 1 root root 4174 Jul 3 23:19 khweeteur-experimental.list
-rw-r--r-- 1 root root 458 Jul 3 23:19 phonestream.list
-rw-r--r-- 1 root root 1601 Jul 3 23:19 ytube.list

Could Advanced-power-monitor have caused the issue?

[edit 3] doubt it...

Also - a full shutdown does not even turn off the BL! Trying a few minutes without the battery.

Re: My backlight is on full _all_ the time - even when blanked
 

A few minutes without the battery made no difference.

R&D mode enabled or disabled makes no difference.

Back on / off, uSD card or out - no difference.

Help!

Re: My backlight is on full _all_ the time - even when blanked
 

- Reflash
- Warranty repair

Re: My backlight is on full _all_ the time - even when blanked
 

Humbug :)


(about to reflash - and doubt theres warranty except under eu "fit for purpose" kind of stuff)

Re: My backlight is on full _all_ the time - even when blanked
 

or custom brightness, worth a shot....

Re: My backlight is on full _all_ the time - even when blanked
 

Cheers Doctor - but doesn't custom brightness just feck with /sys/class/backlight/acx565akm/brightness? Been there - does nothing... sadly.

Re: My backlight is on full _all_ the time - even when blanked
 

Ok - reflash has not helped.

Whatever I put in /sys/class/backlight/acx565akm/brightness is reflected in the same file. Also /sys/class/backlight/acx565akm/actual_brightness changes with it.

So current thinking - there must be a FET on the board that drives the LED's and it's gone open circuit. Anyone got a circuit diagram?

Re: My backlight is on full _all_ the time - even when blanked
 

Found: Nokia_N900_RX-51_Schematics.pdf

Page 6 - "LCD Backlight LED driver" (N3150), some resistors, caps, trannies some driver called D3150 between the cpu and the screen flex cable.

Interestingly (fresh re-flash remember, stock kernel etc, nothing installed or running) the bq27xxx/i2cset probe script shows a constant current usage over 160mA whether the screen is locked or not. (max 250mA)

Re: My backlight is on full _all_ the time - even when blanked
 

Arggh I really want an N950 now....

Re: My backlight is on full _all_ the time - even when blanked
 

Weird weird weird.
When I got home - I was using the N900, well trying to work out what was going on whilst making backups.

The battery got to critical (much quicker than normal of course) and the backlight dropped to normal levels... and was controllable and even went off when the phone is locked!!!

It seems to working fine now. (phone locked current between 12 and 24ma - muuuch better!)

Just after I bought a 2nd hand on ebay.
ARRRRRRRRRRRRRRRRRRRRRRRRRRRRRRGGHH