Modifying a 3.5" car display for USB power.

[thak]

Well...

I try earlier this afternoon and desolder the chip then try run the screen on 5v... Nothing at all. But I think i may be in fault with my poor skill in desoldering...

So i will buy a new one soon yo give an anotjer shot and hoping the circuit board will be the same as some of them showing in this topic

[Oeasis]

Thanks boobatron3000 and nox86 and sorry for not getting back sooner. I still haven't managed to get this board to work and I suspect I might have broken it by now. I'm probably going to buy another LCD so we'll see what strange new board design I come back with.

Here's what I tried
Soldering the red wire to the small, right tab on the AMS1117 regulator ( nothing happened)
Soldering the red wire to the large, top tab on the AMS1117 regulator ( nothing happened)
Soldering the red and black wires to the 5V and ground points nox86 pointed out ( still nothing)
By now I thought I'd probably messed the board up in some way with all my dodgy soldering and accidental slips with the soldering iron. So in one last attempt to see if I could get something at all to happen I replaced the red wire with a 20V one, and after a couple of sparks the lcd started smoking. (something happened )

I'm new to soldering so that might be why I couldn't get it to work, also I'm using a raspberry pi b+ with this cable "https://www.modmypi.com/audio-video-composite-cable". Not sure if that makes a difference but I tested the cable with the pi and another tv so I know it works. Thanks again and hopefully the next LCD I get wont have to meet the same end

[earthdragon186]

This works for me:

http://www.suckmypic.net/73677/IMG_20140823_145147.jpg
http://www.suckmypic.net/73678/IMG_20140823_145159.jpg

The red wires source is @ 5v. i didnt remove any component from the pcb.

Hey brain1024,

I saw that you answered to kammron's board problem by two pictures. I have difficulties with the same board, but can't download your pictures (error 404). Would you be so kind to help me by posting the pictures again or writing me what to do? I so far did not modify the board but just plugged 5v instead of 12v. The screen flickers on and off, it seems like supply is breaking down (with 2000mA power supply). Also, do you know how much power your solution needs? I'm thinking of a battery suppy, but with 2.2A@5v, for me it seems a hopeless case to find a fitting battery.
Thank you very much in advance!

[NeSs1]

Hi to all, someone can help me with this cheap 4,3" monitor? I need to power it on 5 volts
Thank you all

P.S.
Sorry for my terrible english, i'm italian


http://www.amazon.it/gp/product/B00CFFLXZ4

[Giandroid]

Hello all, I have the same exact screen as DarkWolf 896. I got it here:

http://www.amazon.com/3-5-Inch-TFT-Moni ... 0045IIZKU/

I would take a picture of the board, but honestly, his are better. I will include them here. I don't quite know where to begin; I don't know which one is the voltage regulator chip. I also would like this screen to run on 5 volts, as it's for a portable computer.

Thanks!

[benjaminhuson]

Hello!

Sorry for hitting this old post up but I'm thinking of doing this same thing, but I have seen a different model (same make, just a different size) of that display which would work a little better for my needs:

http://www.amazon.co.uk/Monitor-Support ... roduct_top

Has anyone tried the same thing with this model of display? If so does it have the same unused 4 pin header etc?

Cheers

[obi81]

Hi volks,...

greets from germany...

got the same problem...

I messured the 5v on the black thing AMS 1117 on the right pin
hooked the red wire on it and it works.
But the board gets realy hot...
is this normal,.????
or must i remove thomething from the 12volts konverterchip ????

greets. martin

PS: sorry for my bad english,.....

[BreakerShadow]

Hey there,

got my Screen today from Amazon, and the board seems to be a lot smaller than all of yours posted previously. Is there someone who can help me out, getting this display working with 5V?

Thank you very much!

[BMS Doug]

Hey there,

got my Screen today from Amazon, and the board seems to be a lot smaller than all of yours posted previously. Is there someone who can help me out, getting this display working with 5V?

Thank you very much!

kind of hard to help remotely without an identical board.

Do you have a voltmeter available to check voltages?

you are looking for a voltage regulator that drops the supplied 12v to 5v. it is likely to be one (or maybe both!) of the two 8pin SMD chips. I can't make out the details printed on the chip from your image.

Giantdroid and DarkWolf896 seem to have the same board as you (turn your image upside down).

Hello all, I have the same exact screen as DarkWolf 896.

Edit: re-reading Giantdroid and darkwolf's posts it seems that the board operates at 3v3, try supplying it with 5v on the input voltage cable, the regulators may be able to cope without any alteration.

[BreakerShadow]

Thank you very much!

I tried to connect it to a 5V source, and you were right - it just worked fine!



To help anybody with the same board - my setup in the picture above is:

3.7V 2200mAh Battery
Battery Charger
Power Boost 500 (Boost your 3.7V to 5V)

Connect the red an black wire from the display to the Power Boost + and -
Connect the white or yellow cable to raspberry pi video output
Fire up the raspberry pi

Should work!

[charliehorse]

Hey all,

Really useful tips; thank you very much!

I recently purchased a similar screen for my Pi to power from USB, but the PCB looks somewhat different. Please can someone help to identify what needs to be changed/removed?

[benjaminhuson]

Hi guys

As per my previous post I purchased this from amazon - http://www.amazon.co.uk/Monitor-Support ... roduct_top

It actually runs on 5v out of the box, no modifying required.

Not sure if that helps anyone else.

Regards

[BMS Doug]

Hey all,

Really useful tips; thank you very much!

I recently purchased a similar screen for my Pi to power from USB, but the PCB looks somewhat different. Please can someone help to identify what needs to be changed/removed?

very hard to tell from the poor resolution image, It would be much easier with the board in front of me.

Firstly try using a 5v power supply to the board, some recent screens have been able to work directly from 5v so why change anything if you don't need to?

If your board won't run from 5v then you'll need to start figuring things out, you have a voltage tester?
apply 12v to the board and use your voltage tester to locate any 5v points on the board (possibly on the points right in the upper right corner of your image, on the pins of the 8 pin chip directly below those connections or on the pins of the 8 pin chip directly above the processor in your image).

[charliehorse]

Thanks for your replies.

I will try to run the board straight from 5V to the board, and will post back.

I can't seem to upload any better pictures directly. Here is a link to two higher res images.
http://postimg.org/image/cvfv9u8gt/
http://postimg.org/image/dls5d3cd3/

[charliehorse]

I can't get it to run from 5V. The top left 8-pin chip is the voltage regulator right? If I remove this, can I rewire it to run from 5V?

[BMS Doug]

I can't get it to run from 5V. The top left 8-pin chip is the voltage regulator right? If I remove this, can I rewire it to run from 5V?

you will need to check with a voltmeter, the component arrangement will vary from board to board.

[BMS Doug]

it looks right, the XL1583 is indeed a voltage regulator. You will need to confirm that the board operates at 5v though.

Page 2 of the previously linked datasheet has the chip pinout diagram.

You would need to desolder the voltage regulator and solder a 5v supply to pin 3.

[MetroidSlayer]

[deleted]

[MetroidSlayer]

This might be old news, but I was able to get this board to run off of 5v. Pictured below, I have a half-charged 3.7v connected to a Powerboost 500c, which is plugged directly into the unmodified screen. When a good input signal was found, the screen turned on!

I might saw off the over hanging PCB where the tact switches were supposed to go. The board should run just fine without that bit.

[Update]
Sawing off the unneeded parts of the PCB worked out okay. The screen was a bit finicky to pick up the signal from the Pi right away, but that was corrected by turning off HDMI hot plug detection. So far, the screen runs perfectly, maintains a stable signal, and is super bright. The pads (both columns) on the bottom right are as follows:
AV2 (yellow)
AV1 (white)
Common Ground (Black)
Power in (Red) <-- designed to accept 12v, but runs fine at 5v.

[MetaParadox]

I realize this is a little old, but I can't get my screen to turn on. I have a similar beaord to one in this thread, but doing what the other guy did does not work. Here is my board: https://imgur.com/a/6HLJ1. Its a newer version than the one posted. All it does when given power and connected to the video port on the pi, is flash white once for a split second, and turn off. If anyone can help me out, it would be much appreciated.

[Gabry295]

Hi AndyA, thank you so much for your guide, it's really easy to understand
I miss only one thing, I can't recognize which one is the 12V to 5V regulator chip, could you help me? I posted 3 photos of my lcd's board, you can see at a higher resolution here:

- the entire board: https://www.dropbox.com/s/504juyv4wn9t3 ... 5.jpg?dl=0
- one chip: https://www.dropbox.com/s/8atilqg4uv26j ... 3.jpg?dl=0
- the other chip: https://www.dropbox.com/s/ro88j2jqynnfj ... 4.jpg?dl=0

I looked on the Internet for the name of both the chips, but I couldn't understand the datasheets and I don't know which one I have to remove since my board is quite different.
Thank you!

[oreosxe]

I have the same board as Charliehorse before. I started off by just attaching the 5volt right into the main power input of board to see if it would work. The board boots up and shows the video input. It looks scratchy and shakey Would this be a side of effect of running the 5v. I think its a good sign that it is doing this but it is not good enough. I saw someone mention removing the XL1583 and soldering my power input to pin 3. Does this seem like the logical next step?

This is what my output looks like: http://www.gfycat.com/NecessaryHastyHeifer

[oreosxe]

Just to update my own question in case someone is in the same boat. I got it running on 5v. I did as BMS Doug suggested. I removed the XL1583 and soldered 5v input directly to pin 3. Plugged it all in and viola it worked!

[Chris74]

Thanks to all for the info in this thread I was able to easily modify my display to run on USB. No components removed and used the original cable.

image3044.jpg

Probably didn't need to move that ground wire, but it just seemed like the right thing to do at the time

Hello,
I'm pretty sure that I have the same PCB for my LCD screen and I tried by several ways to supply it with 5V (using pins of GPIO, adapting a wire from a USB port using the original cable...) and impossible to have the signal. I only had a white screen...

So I tried to connect it to 12V with the original cable and it worked well...

Could you please help me ?
Thanks.

[xen956]

Hello guys,

I have got what seems to be a new version of the board. I don't see any 5V connector or anything, except that when I measured in few places, I do get 3.3V and 5V. I don't have a 5V power supply yet, but would anybody already be able to spot if this can be ran with 5V or what mods are needed?



(open in new tab for big version)

The 8 pin component in the middle has "25X20BLNIG" written on it and the one on the top left has XL1509.

Cheers!