Glo Controlling the Glo's Frontlight

[yoq]

It has no effect on power consumption, the current which flows is still the same, just a tiny bit of it goes into the resistor. At lower levels when not much current flows, this makes the LEDs darker. On higher levels you can't see the difference.
So it's no short circuit, 33k is about as conductive as human skin.

[TechniSol]

Battery shouldn't change -but it won't improve either as you might expect, since you're lowering the brightness. He said the LEDs are driven with a PWM adjustable constant current source. If he's just paralleling the resistor with the LEDs then he's just diverting some of the current they'd get at any given brightness level, so reducing their overall brightness a bit -mostly apparent on the low end.

Had a look inside my Glo. Phew. Going to need the BIG lighted magnifying glass for this one. I may wise up and get the local HDTV repair guy to stick this resistor in for me since he has a nice surface mount rig in his shop.

Whoops he beat me to it... Apparently, I failed to note there was another page to the thread and replied at the bottom of the previous one. DOH!

[staropram]

Wow, just wow. Some badass shit going down in this thread

yoq, can you re-upload the schematic somewhere, for some reason the link doesn't work?

[staropram]

Sorry, I double posted.

[yoq]

Originally Posted by staropram

yoq, can you re-upload the schematic somewhere, for some reason the link doesn't work?

Fixed; it's not much though, just confirmation that it is a step-up converter.

[met67]

Originally Posted by akorx

Hi Yoq !

I really want to reduce the brightness under the min... I've found a resistor like yours and tried to solder it but without success, it's really too too hard for me.

Did you manage to solder a normal size resistor? Are you happy with the result?

[akorx]

Hi met67,

I've tried to solder it during 10 min but without success... My iron is a 19W with a small tip but it's really too difficult for me, the resistor glue to my iron and not on the motherboard.

Do you know if "cold welding" should be a solution (like this http://www.youtube.com/watch?v=dfNByi-rrO4) or this http://www.mcmelectronics.com/produc...A%26dur%3D1825 ?

[yoq]

Originally Posted by akorx

Hi met67,

I've tried to solder it during 10 min but without success... My iron is a 19W with a small tip but it's really too difficult for me, the resistor glue to my iron and not on the motherboard.

Do you know if "cold welding" should be a solution (like this http://www.youtube.com/watch?v=dfNByi-rrO4) or this http://www.mcmelectronics.com/produc...A%26dur%3D1825 ?

Are you using tweezers to hold the resistor down?
Also, it's important to keep in mind that most of the heat must go into the board, so always hold the iron on the board first for 1-2sec and then add solder.
That's the proper way to solder a SMD resistor: http://www.youtube.com/watch?v=EWeAOemTY_E

The thing with silver paint could work but it's a messy solution, I wouldn't do that.

[met67]

Originally Posted by akorx

Hi met67,

I've tried to solder it during 10 min but without success... My iron is a 19W with a small tip but it's really too difficult for me, the resistor glue to my iron and not on the motherboard.

Do you know if "cold welding" should be a solution (?

I'm not a hardware guy, so my guess is as good as yours

[akorx]

Is there another place where we can put a resistor that is more accessible and less risky (or an other electronic component) ?

And if it's possible, how many ohms ?

[yoq]

Originally Posted by akorx

Is there another place where we can put a resistor that is more accessible and less risky (or an other electronic component) ?

And if it's possible, how many ohms ?

Just connect anything from the red area with the blue area via a 33k resistor.
If you want to use a bigger wired resistor, try the two green spots.

[akorx]

Thx Yoq for this, I will try...

But just a question before, because I think you make a mistake : as you can see in blue there is a resistor ("000"), and what you are telling me is that "all the blue" is the same pin... so that means that this resitor is not used ... are you sure of it????

[yoq]

Originally Posted by akorx

Thx Yoq for this, I will try...

But just a question before, because I think you make a mistake : as you can see in blue there is a resistor ("000"), and what you are telling me is that "all the blue" is the same pin... so that means that this resitor is not used ... are you sure of it????

Yes, it is a zero-ohm resistor, a bridge:
http://en.wikipedia.org/wiki/Zero-ohm_link

[akorx]

I will try to find another resistor 33k ohms on an old card...

Meanwhile, I've got a little question : in one of the first pages, Kevinshort has written this :

I've noticed that if I plug my Glo into a USB cable and turn the frontlight on and then off that the LEDs will often go dimmer than the lowest level for a few seconds. I'd say that it's about half as bright as the lowest setting, and hardly noticeable in a bright room.
...
Don't disconnect the USB; the light goes dim immediately after you press the light button to turn the frontlight off. Here are my steps:

1. Plug USB into Glo, choose cancel when asked to connect to PC.
2. Turn on frontlight.
3. Turn off frontlight. The light goes dim for a second, then goes completely off.

Sometimes the frontlight only goes dimmer for a fraction of a second, and you'd miss it if you weren't looking for it. A few times, I've had it stay at half-brightness for 10-15 seconds.

The entire post is here : https://www.mobileread.com/forums/sho...=200706&page=2 with photos...

Does it mean that there is a software solution to reduce brightness?

[yoq]

This indeed sounded like a software solution is possible, but I could never reproduce the phenomenon on my Kobo. All i can see when shutting the light off, is that the light fades out before shutting off completely. So I figured this might have been a hardware issue, and "fixed" in a new revision of the mainboard.
However, it could also depend on the firmware, and I only started looking into it when 2.5.1 came out, so I can't tell. Can you reproduce it, akorx?