Half of My LCD Lights Up

[Axaday]

This is actually new. I've been trying to just tweak inside (and I retouched every solder and am sure they are good) and when I plug it into my laptop, I get a regular screen that twitches. What I mean by that is that it usually shows nothing but every second or so a vertical line appears on one of the places and disappears. But when I push all 3 buttons to get the setup screen, it displays this in living color:

[dcb]

I think you were on to something with the ohm readings. I didn't see any serious connectivity between any lcd pins except the common ground ones.

Edit, and the fact that the behavior is changing is a sign that something is flaky.

[dcb]

Also, it is just the left and right button now to get to the setup screen (got tired of accidentally resetting the tank or current trip).

[Axaday]

Some of the green area around the solder points on the LCD is extra glisteny. Would that indicate that I've gotten it too hot and the inside of the circuit may be damaged? I don't know how to get precise readings on my multimeter, but now I'm getting between 3 and 5 with it set on RX10 when I touch just about any two points on the LCD, which makes me think that I've ruined another one.

Edit - Actually, I might just be a stupid head. I said "about any two points", but all I was doing was any point and ground and that might be okay, right?

I just put it back in the car just for grins and it is still behaving the same in the car as before. It is trying to show me instant and current mpg, but it is doing it with half the screen inoperative and the other have uncontrasted so you have to look at it at an angle.

[dcb]

Well, you should be able to stumble on a contrast that works, like wyatt mentioned. Just hit left+right then in the setup screen hit middle till you can read it good.

Then feel your way over to the OK "button". If you go all the to the left character, then quickly but carefully hit the left button twice you should be there. quickly as in press and release the button quickly, but wait a 1/2 second before the second press.

Then do that for all the other settings and see if the contrast stays ok at least.


Test continuity between all points. Except for LCD 1,5,16 they should be about 10k or more apart. Send a pic of your ohmeter if you like.

[Axaday]

Originally Posted by dcb

Well, you should be able to stumble on a contrast that works, like wyatt mentioned. Just hit left+right then in the setup screen hit middle till you can read it good.

Then feel your way over to the OK "button". If you go all the to the left character, then quickly but carefully hit the left button twice you should be there. quickly as in press and release the button quickly, but wait a 1/2 second before the second press.

Ok, I was aiming for ONE left of the left character. I'll do better in a few minutes.

Test continuity between all points. Except for LCD 1,5,16 they should be about 10k or more apart. Send a pic of your ohmeter if you like.

I don't know what I was thinking in my last edit. Of COURSE it isn't okay that every pin is showing some continuity with ground. Even the power wire is doing it. I think I've melted the circuits inside the LCD with too much soldering.

If it is giving me calculations and running through the setup screens, does that pretty much indicate that everything is sound except my LCD? Is there an LCD out there that is going to be easier to install for a hamhanded solderer like me?

[dcb]

Of course you have the power unplugged when taking these readings?

[Axaday]

Yes, unplugged it is showing an alarming amount of connectivity. I think I'm reading right that nearly every pin, including the power, has only 30-50 ohms of resistance to ground.

Going TWO left from left worked. It saved my settings. Which means I COULD start using it. It appears that I can read the instant and current MPG without the other half of the screen. But do I run a risk of damaging the computer with all of those pins grounded? Would it be a lot safer to wait until I can get another LCD?

[dcb]

I think you have to look somewhere else than the lcd, this is your second one no? Same symptoms?

The meter is on x10 and not x10K ?

[Axaday]

Originally Posted by dcb

I think you have to look somewhere else than the lcd, this is your second one no? Same symptoms?

It is my second LCD. But the symptoms aren't quite the same. The first one put white blocks on the right side of the screen and left the left side blue. This one showed while blocks all the way across until I got the contrast adjusted and now it works right on the left side and has white blocks on the right side.

The meter is on x10 and not x10K ?

Yes, Rx10. The only non-ground wire on the LCD that isn't showing around 30 ohms from ground is 15. I can't think how that could possibly be other than the LCD being damaged.