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Author Topic: DIY Laptop, charging curcuit / display controller board  (Read 1178 times)
Chairmander
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« on: September 20, 2016, 10:07:52 PM »

EDIT: Damn, I finally understood the sorting in this forum (took me some time, eh?), so I guess I really am quite off-topic in "Screen Tablet malarky" so... just ignore my problem number 1 and help me with the screen I guess? Sorry for that

First time poster, I hope my question isn't too off-topic (and too long) since I don't build a cintiq or anything wacom related for that matter, but a laptop as a whole. But hey, at least I'll use a wacom tablet externally with this laptop, so at least some correlation? Cheesy
Anyways, first some data about my parts:
the brain - UP-board w/ 4GB RAM and 32GB eMMC (5V@~1.5A with keyboard and mouse)
the brain extension - mSata Shield with WiFi module (12V@?A - also provides power for the UP-board, but I haven't measured the whole package yet, I'd guess it needs about 2A)
the display & controller board - LP171WU1 TL A7 screen powered by a T.VST59.031 controller board (12V@~1.2A)
now some data about my level of knowledge, so you know at which level you can talk to me Wink :
I'm in a school for mechanical, electrical and software engineering, so there are many different (technical) topics about which I don't know that much.
For the electronics part I know about:
basic electrical principles (Ohm's Law, Kirchhoff's curcuit laws, how capacitors, transistors, resistors work and how I can calculate stuff with them), some stuff about OpAmps, some basic knowledge about AC curcuitry, and how to use various measurement devices (Oscilloscope, Volt- and Ampmeter,...), but thats about it. (I also don't have much practice, so much of this stuff is half forgotten)

Sooooo, right now I have two main problems (for which I desperately need help, I just don't know what to do anymore) with my laptop build:
1)
Where do I get a proper Li Ion charger from, as well as a power distributor (those things that automatically switch from battery power to external power, I don't really know how they are called). I found some parts for this by Texas Instruments, but they are impossible for me to use due to several reasons: the chip itself is incredible small and has 28 pins and is therefore nearly impossible to solder by hand, it needs an absolute incredulous amount of peripheral electronics aaaaaaaand it does way more than I need it to (eg it also includes every possible type of battery safety, which I plan to include as a pre-built module with the battery and not with the charging controller). Other than that I haven't found any pre-built chargers/distributors which can handle the amount of power I need. Since I have rather powerful components I have to be able to put 12V at about 3-4A through - and thats not counting possible power hungry peripherals (like a charging mobile phone).
And if there are no pre-built controllers for my use - how do these things work? I really don't want to go datasheet hunting without really knowing the electronical principles behind most of the stuff.
I understand, that I will need some sort of current measurement device, which knows how much power gets into/out of my battery, into my system and how much in total gets into my laptop via the power plug and I know that Li Ion batteries have special charging needs for which I need to be able to switch between constant current and constant voltage mode, as well as do pre-conditioning and voltage maintance - but how do I switch these? And how can I switch fast enough between external power and battery, so that a capacitor can buffer the outage and my board doesn't turn off?

2)
the screen. It. just. doesn't. work. I don't know why. Maybe it's the screen itself. Maybe it's the display controller. I just don't know. The only thing I can see on it is white after about 10 seconds of weird pixel errors, which I think is just because the display controller needs some time to start up, but could also be because of a faulty display. Unfortunately, the laptop the display originated from is absolutely broken (well, now somewhere on the garbage dump), so I can't even check if the display works or not.

Images of the screen booting up (disclaimer: those darker spots are [mainly] not from the camera, this is nearly what the screen actually displays):
directly after bootup

some seconds later

(the images show the whole screen)
The screen slowly gets brighter until it is completely white after about 10 seconds

I am ready to buy a new screen, but if I do this I would like to get the complete package and not have to hack something together (so, no external display controller, just a screen where I can plug my damn HDMI cable in), so if any of you know of any good screens that meet my criteria (preferably 15.6", but 12-17" is okay, FullHD and HDMI or something for which cheap adapters exist) I would be forever grateful, because I can't find such a thing and I could at least use the laptop, just with constant external power.

links:
UP-board: http://up-shop.org/up-boards/43-up-board-4b-32-gb-emmc-memory.html
SSD Shield: http://up-shop.org/home/54-502ssd-msata-solid-state-drive-shield.html
T.VST59 controller board: http://junhengtai.en.alibaba.com/product/60414637756-801852502/T_VST59_031_LCD_Mainboard_Manufacturer_And_Supplier.html
« Last Edit: September 20, 2016, 11:25:22 PM by Chairmander » Logged
Ertew
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« Reply #1 on: September 27, 2016, 10:46:43 PM »

This vertical is a LCD fault.
Depend on nature of this fault, LCD can be usable (just one strip have different shade), unusable (strip stay at wite/gray while rest of display working) or faulty (backlight working, LCD will never work again).
In my opinion, this can be good training material to learn how to disassembly and assembly LCD. Nothing more. You should try to buy new LCD screen. Model with EDP input instead of LVDS will be better because Your board have EDP output.
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Chairmander
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« Reply #2 on: October 02, 2016, 03:12:43 PM »

Yeah, I thought so, I already looked into some different screens and have found a 15,6” screen with eDP, but i still struggle to find the right cable, since I don't know exactly which connector I have and the screen is in delivery right now - I'll post the solution to all of this once I can get back to it
thank you for clarification regarding the screen Smiley
« Last Edit: October 02, 2016, 06:15:45 PM by Chairmander » Logged
Pesho
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« Reply #3 on: October 02, 2016, 06:28:26 PM »

Usually the connector brand and model are written in the datasheet for your display. Most of the time they're manufactured by JAE, sometimes I-PEX or Cvilux.
« Last Edit: October 02, 2016, 06:30:01 PM by Pesho » Logged
Chairmander
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« Reply #4 on: October 03, 2016, 10:35:47 PM »

The screen needs (or has? I'm not entirely sure) the connector HRS KN38B-30S-0.5H, although it says a JAE connector works as well ("[...], or a JAE equivalent"). But I can't find it even on the official Hirose/JAE site (I was able to find the connector the UP-Board has, but the "find mating connectors" function doesn't work for me), sooooo if anyone could show me where I can get such a cable, it would be nice. Also, I guess I'll have to request a custom cable, since there are (probably) different connectors on both sides (since I really don't want to solder two of these cables together, because they are so small and delicate and it will probably cause interference)
PS: The screen I chose is this one: http://www.datadisplay-group.com/fileadmin/pdf/produkte/Displays/LG/LP156WF6-SPB1_Datasheet.pdf and the UP-Board has a FH35C-41S-0.3SHW(50) connector
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Pesho
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« Reply #5 on: October 04, 2016, 10:05:25 AM »

Most of the time the seller of the display controller boards will look at the datasheet and fashion a cable with that connector. For LVDS it's the mating connector for the LCD on one side, and on the other it's a standard 2.54mm duPont-type header connector. It's probably the same for eDP, so it's easiest to ask them to make a cable for you, they're about 5$ or so. If the connector on the LCD side is the same as your old display, all you'd need to do is make sure the pins on the board correspond to the ones in the LCD's datasheet and rearrange them if necessary.
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