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[Q] Nook Simple Touch cracked lcd screen

26th January 2014, 10:44 PM |#1  
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Hello,

I've accidentally cracked my NOOK ST (without glowlight) lcd screen recently. As I was looking for a new lcd on eBay I've got an idea to make my NOOK a glowlight. Would it be possible if I just bought myself a NOOK ST with glowlight lcd screen and simply replace my cracked one with it? I don't expect it to be that easy, but maybe there's a chance anyway? I really like my NOOK ST and wouldn't want any other e-reader.

Also could anyone advice me with what type of lcd screen can I buy for NOOK ST? The original ones seem to cost a fortune, so maybe it's possible just to buy any other lcd screen of the same size and replace it?

Thank you
Last edited by sh4liX; 26th January 2014 at 10:49 PM.
 
 
14th April 2015, 01:17 PM |#2  
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Can anyone comment on this one? I've some horizontal lines on my Nook w/o glo.
14th April 2015, 04:00 PM |#3  
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Well... It seems that those devices use exactly the same eInk panel. Assembly on the NSTwG has only those additional elements:
1. Additional light dispersion layer between the eInk panel and the matte protective sticker (yup, Nook has something like that straight from the factory) - this is the one responsible for infamous "light leaks".
2. A strip of tiny SMD LEDs with a connector, taped to the screen assembly right on the upper edge:

Simple circuit of LEDs, no additional elements.

3. A socket on the motherboard for the LED connector:


I've tried to investigate in which pins the current should flow to power the LEDs, but due to the imprecision of my power adapter voltage regulation and too big probes the results have only 80% of certainty. But I am absolutely confident that those LEDs did behave as follows:
- no light at 1,5V
- weak light at 3V
- strong light at 4,5V (I did not went higher to protect the leds)

Edit:[It turned out that my power supply unit is malfunctioning an it sends quite a different voltage than it is supposed to at a given potentiometer setting. So I've measured what voltage those LEDs do actually get from the Nook when the Glowlight is on:
11,67 V at full power
11,11 V at around 1/2 power
10,76 V at around 1/4 power
10,10 V at minimum power.
]

Conclusion: you should be able to use the screen from the NSTwG in the regular NST, and the backlight should work if only you can think of a way of supplying and regulating the current (maybe with a potentiometer lead out from the case) either from the Nook itself or from an external battery stored with the ereader in its etui/cover?

And by the way - for the replacement screens look at:
Used ones at powerbookmedic.com : http://www.powerbookmedic.com/Nook-S...y-p-22957.html
Or new ones at alibaba with glowlight: http://www.alibaba.com/product-detai...341677644.html
or without it: http://www.alibaba.com/trade/search?...60SCE+%28LF%29

Cheers!

Bonus: the LED strip transplanted from one NSTwG to another NSTwG without the rest of the screen assembly:
Last edited by thrackanomir; 15th April 2015 at 03:38 PM. Reason: Data correction and new measurements.
16th April 2015, 10:31 AM |#4  
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There are 8 white LEDs on the little board.
They are divided into two serial chains.
They are being driven by a constant current supply.
That means that the voltage drop on a white led is about 2.5V x 4 = about 10V.
The exact voltage varies with temperature and current.
You can't say that 11.095V gives you half brightness.
You need to drive them off a circuit that regulates the current, not the voltage.

I don't know if the LEDs are driven off the standard PMIC, but I would guess that they are.
16th April 2015, 12:32 PM |#5  
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Thank you for the correction, Renate NST. I am only a layman with a screwdriver, a multimeter, a soldering iron and a liking for DIY projects. With hardly any knowledge about electronics, to be honest.
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