634 backlight problems


New member
I have my 634 hooked up with a pic microchip, so I'm using the solder connectors J2. I'm using it in the 1200 baud mode, and it's working fine, displaying the messages and all. The only problem I'm having is turning the backlight on. Any ideas of what could be going on?
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USB LCD Displays - Graphic and Character LCDs with a Keypad


New member
Yes, 5V is supplied on both the LCD and the LED.

Also, I know my SerOut commands work because I can change the contrast, set the cursor position, etc... besides just displaying messages. I'm sending 14 and then 100 to it. I even tried a loop from 0 to 100 to see if there was a point where it worked, but had no success.

I've tested two LCD displays, with the same results. I can do everything but turn the backlight on.
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CF Support

The last order you placed had only the NFA variant of the 634 present, so you can't switch on the backlight because it's not there.

Hopefully that'll end the frustration with getting the backlight to turn on.


New member
Well, thanks for the help.
Iwasn't the one who ordered the displays, so I didn't know.
Just for the heck of it, this is the part number,
SKD204-634 V2.2

CF Tech

No problem.

That is actually the PCB number, which is used on several modules in that family.