• We recently switched our forum platform. If you experience any issues please email support@crystalfontz.com

634 USB Problems


New member
From what I gather my 634 USB(ver 2.2) doesn't have the "usb board" hence making it a serial module. I noticed this from another post that referenced JPF. Anyhow I'm using a straight through serial cable and it's not powering up. I have used two different laptops here at work and plan to try another here in a few. From what I can tell it's configured for serial mode (JPA open) is there anything I'm missing? I've read the manual and I don't see anything that helps.
Looking for additional LCD resources? Check out our LCD blog for the latest developments in LCD technology.

CF Tech

Please compare your module with this photo:

The cable plugs in from the left in this photo, between the daughter board and the main board, just underneath the Crystalfontz logo on the daughterboard.
USB LCD Displays - Graphic and Character LCDs with a Keypad


New member
My usb board is invisible

I know this even though I do not have it in front of me. If that photo is true and accurate then I do not have the usb version as I am able to read the "closed" list. I double checked my invoice and noticed it did say "USB 634". If needed I'll take a photo of my board.
Last edited:


New member
Did it work though??

From what I read you can power the display over serial but without backlighting (from what I recall I think I ordered it without backlighting). I snag'd a cable at work to test it out but nothing happened. I think you need a young priest and a old priest along with a nun in order for it to work.:D


New member
The advantage of a USB cable is that it provides both signal and power with one cable. A serial cable only provides the signal. You will have to use a floppy power connector to provide the juice. A prayer or two never hurts either. The exact same thing happened to me. There probably isn't a floppy power connector because CF only installs them if you order the serial cable. CF will make it right, they did for me.