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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.
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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.


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.
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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.
USB LCD Displays - Graphic and Character LCDs with a Keypad