LED mod trouble...

madc0w · Post by **madc0w** » Fri Dec 30, 2005 7:34 pm

because you keep pressing quote since its next to the edit button?

Kurt_ · Post by **Kurt_** » Fri Dec 30, 2005 7:44 pm

Perhaps. Anyways on a side note the connection to the 2nd headphone jack broke and I don't want to resolder a whole 5 things!

I'd rather short them for now, I searched (clearly not well enough though) and didn't find much. How do I short them (on a verge screen)

EDIT: I shorted them, but I also used some better ribbon cable and hooked them up.

Kurt_ · Post by **Kurt_** » Sat Dec 31, 2005 11:49 am

Somebody has GOT to have had this problem before! I can't get another screen, this is already my 2nd one and my dad never liked me using my money like this in the first place.

Volume high: No problem
Volume Low: no problem

At least one person reading this should be able to tell me here the problem is? Like on a position on the board.

A.J. Franzman · Post by **A.J. Franzman** » Sat Dec 31, 2005 7:01 pm

It could be your power supply putting out too much voltage. Loud sound draws more power, and the voltage "sags" down to where it should always be. Check the input volts both when you have a normal screen and when it's inverted. Try another power supply if you have one. If it isn't that, check the outputs of the regulators. One might be bad, or have a bad ground connection.

Kurt_ · Post by **Kurt_** » Sat Dec 31, 2005 7:50 pm

I was thinking about something like that. I'll try it tomorow, maybe. But the thing is I'm still using my original power supply. Perhaps the removal of the backlight caused an increased voltage elsewhere? I heard these Verge screens are wired weird.

EDIT: The voltage coming out of one of the regulators is normal. 4.70 and spiked at 3.2 when the volume was loud. (You can spike down, right?)

Where exactly does the power go into the LCD? Does anyone have pinouts for the ribbon cable? I'll check the stickies.

timmeh87 · Post by **timmeh87** » Sun Jan 01, 2006 5:34 pm

this whole time i was suspecting voltage troubles. thats why i told you to get rid of the led's hook up the original backlight and see if it works normally again.

also, if youre looking for spikes, dont use the digital multimeter, as it takes a moving average of the voltage, which smooths out the spikes. use the analog one.

you could try putting a bigger cap across the input lines, but the one that is there is already 1mF (

). heck, maybe a SMALLER cap might work better. ill lend you one of my 10uF tants.

Kurt_ · Post by **Kurt_** » Mon Jan 02, 2006 3:48 pm

Well a bigger/smaller capacitor on the regulator ON the board didn't work.

However, I solved the problem with one easy fix:

I replaced a 1000uf capaticor with a 2200uf one.

It's hard to explain where it was. I guess I could say right where the 7.5V come in. There's 2 capacitors on a circuit board there, and I replaced the one closest to the screen.

Turbo Tax 1.0 · Post by **Turbo Tax 1.0** » Mon Jan 02, 2006 4:06 pm

how did you do this mod if you didnt even take it out of the case fully

But the thing is...I didn't even fully remove it from it's original case yet

did you follow the guide on extreme tech that has tyhe section from bens book

Kurt_ · Post by **Kurt_** » Mon Jan 02, 2006 5:08 pm

I had it working! I swear. But now I don't. At least now I know where the problem is. The screen works for a split second when I poke the capacitor onto the board. It will work for that split second as long as the capacitor is discharged before you connect it.

Any suggestions on what to do?

@ TurboTax:

Well it ISN"T out of its case, just the back and bottom are removed and dangling out

Kurt_ · Post by **Kurt_** » Mon Jan 02, 2006 7:06 pm

Well I solved it (for real this time!)

On the little board where the power input is, there was C2 and C3 labelled on the board, with little outlines of 2 capacitors. And a 3.1 ohm resistor was bridging them together. What a fix eh? So I shoved 2 1000uf resistors in there spots, and it works perfectly now. Hurrah!

And Kids, the moral of the story is:

When experience high voltage problems, always check the decoupling capacitors before you blame it on the voltage regulators!

superdeformed · Post by **superdeformed** » Mon Jan 02, 2006 7:37 pm

Kurt_ wrote:Well I solved it (for real this time!)

On the little board where the power input is, there was C2 and C3 labelled on the board, with little outlines of 2 capacitors. And a 3.1 ohm resistor was bridging them together. What a fix eh? So I shoved 2 1000uf resistors in there spots, and it works perfectly now. Hurrah!

Are you using the original power supply and everything with the screen (I think you said it before but I want to be clear). If you are, then disconnecting the backlight is almost definetly what caused the problem. The AC adapter they give you with the screen is a 1500 mA unregulated 7.5V supply. Since it's unregulated, it sits at about 14V with no load, and with the load from the screen well over 8V. The regulator inside the screen's base is a 7808 with a resistor to drop the voltage to the desired 7.5V based on the load from the controller board. Changing the load from the control board would therefor increase/decrease the supplied voltage accordingly.

When you tried it again with the capacitors in place, did you have the backlight plugged in?

Kurt_ · Post by **Kurt_** » Mon Jan 02, 2006 7:56 pm

The backlight IS what caused the problem, there is no doubt in my mind.

- Yes I'm still using the original power source

- It works now, without the backlight