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serial 634 backlight killing display!?

partofthething

New member
Hi, I'm having a big problem with my serial CF 634 LCD. I have a great setup in my car but recently, when I toggle the backlight on or off, all the text disappears! Turning the backlight on and off repeatedly sometimes (rarely) brings the text back. All I am left with is a blank, backlit screen! I'm using that "LCD winamp plugin v.0.6.4" for this operation. When I close winamp, crystalcontrol takes over but it doesn't have any text either. The only way to get it back is to pull the serial cable out the screen and plug it back in. This results in high-contrast squares that can be reduced to normal contrast by restarting winamp. This phenomenon occurs with both long and short serial cables. I'm running at highest baud rate. I found no references to this problem on the plugin's site. Please help! Thanks a lot.
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partofthething

New member
it's SKD204-634 v2.2
The power is coming from the +5V output of a computer power supply which gets its power from an inverter in the car. The wire is soldered to the board along with one for ground. I did not attach the +5V (LCD) connection since the LCD is powered from the serial port.

In other news, I've found that if I run the Boot screen setup utility, the text comes back without pulling the cable. Just running the crystalcontrol program does not work. Only the boot screen utility seems to set things right.
 

partofthething

New member
but why does it happen?

even though I found a way to get the text back, I still need to know why it disappears in the first place. I can't use my backlight at all anymore because it just crashes the screen almost every time I use it. please help!
 
USB LCD Displays - Graphic and Character LCDs with a Keypad

CF Tech

Administrator
From the PC power supply, you should run two fairly heavy wires (twisted if possible). One red for +5v and one black for ground. These should connect to +5v(LED) and Ground on the display.

The red wire should be fused inside the PC's case.

This is an addition to the serial cable.

Can you conrirm if this is how you did it?
 

partofthething

New member
I have the connections right. I made an extension power line using one of the harnesses used in hard drives and plugged it right into one of the power supplies connections. The wires, however are NOT very heavy.

I just tried heavier wires. Same result. The good news is that I tried the system with a different computer and everything works fine! So it seems that the LCD is having no trouble, it's the computer system. Now to figure out what the problem is...

thanks a lot
 

partofthething

New member
latest question

ok, I can't get it to work on my windows 98 machine. It works perfectly on my windows 2000 computer. So now the question becomes "are there any serial port settings that I should specify in BIOS or windows?"
 

CF Tech

Administrator
Any modern software will override any BIOS or Windows settings, so they do not usually matter (they are for legacy applications).

Could just be some oddity of the serial port.
 

partofthething

New member
dual booting

I set the computer up for a dual boot with windows 2000. It works perfectly on the 2000 drive but not on win98 with the same exact settings. This is interesting, but I'd really like to have windows 98 work because it loads much faster on this computer. If anyone has any clue why windows 98 would mess this up and 2000 wouldn't, let me know. thanks
 
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