LordRepusv
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4.3" Screen powered by 5v instead of 12v

Thu Oct 15, 2015 4:14 pm

Hello,
I have just bought a Raspberry Pi 2 and a cheap 4,3" screen (for cars i think). It is originally a 12v powered but I have seen that it is possible to make it work in 5v. I have seen some tutorial on how to do the wiring but I was not able to find the same components positions as my screen's.

Here is it:
Image

So where do I connect the red wire so it work in 5v?

Cordially.

EDIT:
Thank you for your answers. I am not able to show the back because it is stick to the screen. The other part (that is not show) is simply the card with 3 buttons (for the menu).
After some tinkering, I have find out that the part circled in red is where I can put the 5v wire. When it is connected, it turns on (not always, sometimes it burn the wire, the area circled in green are other parts that make the wire burn).
Image

So, do you think I need to weld the red wire to this part? The problem is that sometimes this part burn or is not working (like it is not working/burning 1/3 times).
Last edited by LordRepusv on Thu Oct 15, 2015 9:16 pm, edited 1 time in total.

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solar3000
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Re: 4.3" Screen powered by 5v instead of 12v

Thu Oct 15, 2015 8:00 pm

how are we supposed to know based on a glare-ful picture of just one side?
did you call the company you got it from?
have you tried puting 5v on it? it won't break, it will either work fine or it will just flicker or not work at all.
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mahjongg
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Re: 4.3" Screen powered by 5v instead of 12v

Thu Oct 15, 2015 8:14 pm

the AMT630 is a 3.3V device, but the bottom right corner 4-wire connector looks much like a micro-USB connector, so the red wire of that one is probably 5V, and a power converter somewhere is possibly converting that 5V to 3V3, but I'm just guessing, its just as possible that a switchmode converter converts the 12V input directly to 3V3 (and 5V), just try to apply 5V to the red USB wire, its my best gamble (but I'm not responsible when you blow up the device). the switch mode converter might blow up if you apply 5V to its output, without having 12V at its input.

the AMT630 data sheet is here: http://www.datasheetq.com/datasheet-dow ... ed1/AMT630

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solar3000
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Re: 4.3" Screen powered by 5v instead of 12v

Fri Oct 16, 2015 1:44 pm

Looks like you edited your original single post.

why would you not try the red and black wires first? isn't that where you feed 12v? so do the same with 5v unless you already destroyed the board when you said you 'burn the wire'.
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Re: 4.3" Screen powered by 5v instead of 12v

Fri Oct 16, 2015 2:19 pm

It looks like many of the 3.5" card reversing monitors, people have been adapting them to 5V operation for ages.

If you haven't destroyed the board by applying power to random parts of it you could probably adapt it to 5V.

If your DC/DC converter is outputting 3V3 it might work OK with 5V as the input voltage, so it is definitely worth trying Solar3000's suggestion of putting 5V onto the normal 12V input line.


looking at your picture, just below the 470 inductor there is an eight pin chip, could you post the details printed on the surface of that chip please?

(that is the logical position for a dc/dc converter chip, the other 8 pin chip is probably memory) (Power next to power, memory next to processor).

The usual process is to de-solder the dc/dc converter chip and solder your 5V supply to it's output, but this only works if your dc/dc converter outputs 5V.
Doug.
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LordRepusv
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Re: 4.3" Screen powered by 5v instead of 12v

Fri Oct 16, 2015 3:39 pm

Hello, thanks for your help.
Here is a picture of the whole board.
Image

It is still working. When I said it burned the wire it is because sometimes, when I touched some chip the wire started making smoke...

On the height pin chip below the 470 inductor is printed this: "CHMC SAB 1509-5.0".

I have tried to simply put 5v instead of 12v by the normal way (on the red wire in the bottom right) but it simply does nothing. It only worked a with 5v when I tried on the highlighted place (see the 1st poste). I didn't really tried anywhere else because I am afraid to destroy the board.

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mahjongg
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Re: 4.3" Screen powered by 5v instead of 12v

Fri Oct 16, 2015 4:20 pm

The CHMC SAB 1509-5.0 is an XL1509 Switching 2A 5V regulator, pin 1 is its (12V) input, and pin 2 is the 5V output.
You can probably feed 5V to pin 2, without feeding 12V to pin 1, but I'm not certain, its probably safer to remove the XL1509.
Note that you also need to give the display a video signal, to display.
Its possible the 12V is used/needed for the backlighting, so maybe feeding the display 5V won't work.

LordRepusv
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Re: 4.3" Screen powered by 5v instead of 12v

Fri Oct 16, 2015 4:36 pm

mahjongg wrote:The CHMC SAB 1509-5.0 is an XL1509 Switching 2A 5V regulator, pin 1 is its (12V) input, and pin 2 is the 5V output.
You can probably feed 5V to pin 2, without feeding 12V to pin 1, but I'm not certain, its probably safer to remove the XL1509.
Note that you also need to give the display a video signal, to display.
Its possible the 12V is used/needed for the backlighting, so maybe feeding the display 5V won't work.
Thank you! I am a newbie in this kind of things... So I don't really know how to remove the XL1509 or where is actually the "pin 2".

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solar3000
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Re: 4.3" Screen powered by 5v instead of 12v

Fri Oct 16, 2015 6:58 pm

LordRepusv wrote:Hello, thanks for your help.
Here is a picture of the whole board.
Image

It is still working. When I said it burned the wire it is because sometimes, when I touched some chip the wire started making smoke...

On the height pin chip below the 470 inductor is printed this: "CHMC SAB 1509-5.0".

I have tried to simply put 5v instead of 12v by the normal way (on the red wire in the bottom right) but it simply does nothing. It only worked a with 5v when I tried on the highlighted place (see the 1st poste). I didn't really tried anywhere else because I am afraid to destroy the board.

oh come on. Another surprise. Now you show us the full picture. I see now, those red/black wires on the upper right go to a remote control.

Anyway, you just answered your own question. No.

However, if you really want 5v, there is an easy way. Either find on ebay: http://www.ebay.com/sch/i.html?_from=R4 ... c&_sacat=0

The other way is what mahjong said. which is actually a little complicated.

I assume you already know smoke=bad.
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Re: 4.3" Screen powered by 5v instead of 12v

Fri Oct 16, 2015 7:01 pm

there are two ways to remove an SO-8 style (the IC package used) from a PCB, a destructive way (IC will be destroyed), and a non destructive way. The destructive way is to cut off all eight pins with a front end cutter, like this:
Image
the non destructive method is by heating the IC with a hot-air desoldering tool, then lifting it off the board with a set of pliers.

Counting IC pins you do by locating pin , then counting counterclockwise around the IC.
Pin 1 is indicated by a dimple or spot on the IC, or pin 1 is on the left hand top side when the IC's "notch" is located up.

Image

another solution is to bypass the IC, by soldering together pins 1 and 2 of the XL1509. You can then input 5V on the original 12V input wire, it should also be safe to do, without removing the IC.

LordRepusv
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Re: 4.3" Screen powered by 5v instead of 12v

Fri Oct 16, 2015 7:18 pm

mahjongg wrote:there are two ways to remove an SO-8 style (the IC package used) from a PCB, a destructive way (IC will be destroyed), and a non destructive way. The destructive way is to cut off all eight pins with a front end cutter, like this: [img]
the non destructive method is by heating the IC with a hot-air desoldering tool, then lifting it off the board with a set of pliers.

Counting IC pins you do by locating pin , then counting counterclockwise around the IC.
Pin 1 is indicated by a dimple or spot on the IC, or pin 1 is on the left hand top side when the IC's "notch" is located up.
[img]
another solution is to bypass the IC, by soldering together pins 1 and 2 of the XL1509. You can then input 5V on the original 12V input wire, it should also be safe to do, without removing the IC.
Thank you. I have tried to put the 5v on it (in fact every where on the board) but in only turn on with 5v on the part highlighted in my 1st post.
So if I remove the IC do you think it will work?
solar3000 wrote:oh come on. Another surprise. Now you show us the full picture. I see now, those red/black wires on the upper right go to a remote control.
Anyway, you just answered your own question. No.
However, if you really want 5v, there is an easy way. Either find on ebay: http://www.ebay.com/sch/i.html?_from=R4 ... c&_sacat=0
The other way is what mahjong said. which is actually a little complicated.
I assume you already know smoke=bad.
Sorry about the pictures :/
I just want to know what do the "buck step up dc"? (as you may find out english is not my native language so it is a bit hard for me to understand). Does it boost the 5v into a 12v so I do not have to make any real modification?

BMS Doug
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Re: 4.3" Screen powered by 5v instead of 12v

Fri Oct 16, 2015 7:50 pm

LordRepusv wrote:
mahjongg wrote:there are two ways to remove an SO-8 style (the IC package used) from a PCB, a destructive way (IC will be destroyed), and a non destructive way. The destructive way is to cut off all eight pins with a front end cutter, like this: [img]
the non destructive method is by heating the IC with a hot-air desoldering tool, then lifting it off the board with a set of pliers.

Counting IC pins you do by locating pin , then counting counterclockwise around the IC.
Pin 1 is indicated by a dimple or spot on the IC, or pin 1 is on the left hand top side when the IC's "notch" is located up.
[img]
another solution is to bypass the IC, by soldering together pins 1 and 2 of the XL1509. You can then input 5V on the original 12V input wire, it should also be safe to do, without removing the IC.
Thank you. I have tried to put the 5v on it (in fact every where on the board) but in only turn on with 5v on the part highlighted in my 1st post.
So if I remove the IC do you think it will work?
Yes, see the 12 page thread that I linked earlier, full of people who have removed a similar chip.
LordRepusv wrote:
solar3000 wrote:oh come on. Another surprise. Now you show us the full picture. I see now, those red/black wires on the upper right go to a remote control.
Anyway, you just answered your own question. No.
However, if you really want 5v, there is an easy way. Either find on ebay: http://www.ebay.com/sch/i.html?_from=R4 ... c&_sacat=0
The other way is what mahjong said. which is actually a little complicated.
I assume you already know smoke=bad.
Sorry about the pictures :/
I just want to know what do the "buck step up dc"? (as you may find out english is not my native language so it is a bit hard for me to understand). Does it boost the 5v into a 12v so I do not have to make any real modification?
Yes, the step up converter will change the 5V to 12V. The cost is the inefficiencies of the conversion process, you'll be wasting power by converting twice which can be important for portable systems. (5V > 12V > 5V).
Doug.
Building Management Systems Engineer.

LordRepusv
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Re: 4.3" Screen powered by 5v instead of 12v

Fri Oct 16, 2015 7:55 pm

Ok! Thanks every one! I will try your answers.
Last edited by LordRepusv on Fri Oct 16, 2015 9:06 pm, edited 1 time in total.

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solar3000
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Re: 4.3" Screen powered by 5v instead of 12v

Fri Oct 16, 2015 8:58 pm

goodbye?

well just don't be near the USA when you connect those wires!
:D Just kidding
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LordRepusv
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Re: 4.3" Screen powered by 5v instead of 12v

Fri Oct 16, 2015 9:06 pm

Just tested -> it is not working :/
The only way for the screen to turn on is by putting the red wire on the part in the up left of the board. Disconnecting the IC did nothing.

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Re: 4.3" Screen powered by 5v instead of 12v

Fri Oct 16, 2015 10:14 pm

LordRepusv wrote:Just tested -> it is not working :/
The only way for the screen to turn on is by putting the red wire on the part in the up left of the board. Disconnecting the IC did nothing.
And you connected the 5V to where Pin 2 used to be as per Mahjongg's post?
Image
Doug.
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LordRepusv
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Re: 4.3" Screen powered by 5v instead of 12v

Sat Oct 17, 2015 10:28 am

BMS Doug wrote:And you connected the 5V to where Pin 2 used to be as per Mahjongg's post?
Yes, It does nothing. But do I have to do something with the ground (black) wire? Because I am still using the normal ground wire (the black wire in the bottom right of the board).

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Re: 4.3" Screen powered by 5v instead of 12v

Sun Oct 18, 2015 12:34 am

BMS Doug wrote: Yes, the step up converter will change the 5V to 12V. The cost is the inefficiencies of the conversion process, you'll be wasting power by converting twice which can be important for portable systems. (5V > 12V > 5V).
???? the XL1509 chip isn't a buck (up) converter, its a drop down converter, converting 12V to 5V, not the other way around.
its a device made for a car, to run on the car's 12V supply.
I'm guessing that the LCD itself (and hopefully also the backlight) runs on 5V, but the composite to LCD decoder chip runs on 3V3, so actually there should be TWO drop down converters, one for 12V to 5V, and one for 5V to 3V3.
The board picture is too bad to read what is printed on both the 8-pin chips I can see, but i'm guessing (again) that both are XL1509 chips and that the one close to the large LCD decoder chip is the one making 3.3V for the large LCD decoder chip.

All the talking about others who removed or bypassed a XL1509 chip to get their device to work on 5V made me "think" you can do the same with this board, but without a schematic, we can never be sure.

If by "black wire" you mean the wire running to the board with the two buttons, then I see no guarantee that it is a GND wire, its more likely the black, (or the white) wire of the four wire cable is the actual ground wire. But again without a schematic all this is just guesswork. But tell you what, there should be a RCA video input plug on the end of the cable, and you can be sure the outer ring of the RCA connector is connected to GND, so you can use the connectivity tester (buzzer) of a multimeter to test which wire it is connected to, and that point will be ground. It should also be connected to the negative (ground) wire of the 12V power input.

LordRepusv
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Re: 4.3" Screen powered by 5v instead of 12v

Sun Oct 18, 2015 2:37 pm

Hello,
So, I think I will buy a new board for my screen. But I do not know where I can find this? I the board could directly work in 5v it would be awesome.

Here are pictures of the screen's... printed cuircuit? (I do not know the name of this).
(Front)
Image
(Back)
Image

BMS Doug
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Re: 4.3" Screen powered by 5v instead of 12v

Sun Oct 18, 2015 5:40 pm

mahjongg wrote:???? the XL1509 chip isn't a buck (up) converter, its a drop down converter, converting 12V to 5V, not the other way around.
I was replying to LordRepusv who had asked about the item that Solar3000 had linked to.

Solar3000 suggested using a 5V to 12V step up converter to take the Pi's 5V up to 12V to get the screen working that way.

A technique that would work but with inefficiencies due to the double conversion that I mentioned.
Doug.
Building Management Systems Engineer.

LordRepusv
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Re: 4.3" Screen powered by 5v instead of 12v

Tue Oct 20, 2015 12:09 pm

Where can I buy another board for my screen?

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RaTTuS
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Re: 4.3" Screen powered by 5v instead of 12v

Tue Oct 20, 2015 12:46 pm

where ever you got the original from
How To ask Questions :- http://www.catb.org/esr/faqs/smart-questions.html
WARNING - some parts of this post may be erroneous YMMV

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LordRepusv
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Re: 4.3" Screen powered by 5v instead of 12v

Tue Oct 20, 2015 12:49 pm

RaTTuS wrote:where ever you got the original from
I bought a normal rearview screen, so I don't know where to buy the board only. This is why I am asking for help.

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