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I've been looking for ages and just can't find any controller boards specifically made for a B140HAK02.2 LCD screen. Here is a photo of the back of the screen:
I've just been googling around, maybe there's a better way? If it helps, the LCD panel is 1080p and has a 40-pin eDP connector and supports touch. Maybe there is some generic board that supports it?
This topic was modified 1 year ago by Oliver
Posted : 18/07/2023 7:42 pm
Useful MT6820-B Universal LVDS LCD Monitor Driver Controller Board 5V 10"- 42" M | eBay
I hate these eBay links but this is probably the sort of thing you're after - they're "universal" although some have to be programmed so it's worth asking the seller. There are quite a few universal devices out there since most LCDs are similar but not quite identical. I've found that reaching out to the people who sell these boards are very helpful.
Take everything I say with a pinch of salt, I might be wrong and it's a very *expensive* way to learn!
Posted : 19/07/2023 12:20 pm
Topic starter
@marcdraco Thanks for the answer. Do you know if drivers for 40 pin eDP panels (in this case 13'') always require a 12V input? I'm trying to pull power straight from the computer so I don't need a separate power brick, but as far as I can tell, USB can only go up to 5V.
Posted : 20/07/2023 5:38 pm
I honestly don't. The voltage inverter is usually on the panel now - so they have a standard voltage input (probably 12v). Your computer's PSU is likely around 19V - some gets lost in the regulators but they are often 80W or more. You can *get* 12v from a 5V USB, in fact Matthew has done that with the USB C microphone that I've been contributing to. That one seems to use a transformer to achieve an impressive 80% efficiency even when producing 30v from 5v in! But you lose a lot of the current in the process, so I would imagine the 12v comes from the internal regulator. The adaptors work in a similar fashion (mine claims to need an 80W supply which is bogus) but they run from a laptop or similar power pack.
But lighting a screen (5v to 12v via an inverter) not likely I'm afraid. USB2 caps out at 2.5W which, at 12V with 100% efficiency is only 200mA and taking account of losses that's likely to drop to 160mA and likely quite a bit less, because the USB won't really give you 500mA without the magic smoke. YMMV of course. A high brightness LED will need 20-40mA and a modern display will have a quite a few.
Take everything I say with a pinch of salt, I might be wrong and it's a very *expensive* way to learn!
Posted : 20/07/2023 10:08 pm
Topic starter
@marcdraco Thanks for the info! I contacted a store in AliExpress that sells control boards and they sent me a link to a perfect solution that works with 5V from micro-USB! making things so much easier... I'm kind of confused though, the title of the product has the model number of my panel, but searching for it on google or directly on Aliexpress didn't show up in the results. Very strange.
Posted : 21/07/2023 8:13 am
marcdraco reacted
That's AliExpress for you, but by and large they are pretty good. Won't lie, I have had some stinkers (including a copy of the JLI2555 condenser capsule) but as a rule and on balance they seem pretty good.
Checking on that device it says it needs 3A supply which is well beyond what the max current is from USB 1 or 2. USB 3.x has a larger current/voltage in the spec. but I'm not fully appraised of what all the options are (my soldering iron, for example, runs from 12V USB 3, in theory from a laptop but I've never tried that. 🙂
But if it works, don't fix it right?!
This post was modified 1 year ago by marcdraco
Take everything I say with a pinch of salt, I might be wrong and it's a very *expensive* way to learn!
Posted : 21/07/2023 3:05 pm
Topic starter
@marcdraco Uh oh, that doesn't sound good. All the ports on the computer I'm working with are 3.1 gen 2, and for USB-C I was able to find sources saying that it can go up to 15W power delivery (5V 3A)
I wasn't able to find anything for sure... But I've placed an order for a control board so I guess we'll see when it arrives haha. Thanks for all the help!
Posted : 21/07/2023 9:25 pm
marcdraco reacted
No worries, fingers crossed. At least modern devices have current limiters (well the good ones do) so it's not like my day when a mistake like that was costly and very smelly. 😉
Take everything I say with a pinch of salt, I might be wrong and it's a very *expensive* way to learn!
Posted : 23/07/2023 12:01 pm