# Specific 3D Printers, Scanners, & Hardware > Other 3D Printers / Scanners / Hardware > QU-BD One Up & Two Up Forum >  Red LED light on the Printrboard

## Monokai

Hello everyone!  
I'm a completly newbie in the 3D printer section and need some help. 

I build together the Oneup and wired up the Printrboard.  Mine is red and not black as shown in the manual.  For the first time it lightet red,  and not green.  In this forum I read about the power connection flip and that the positive wires are on the side that looks to the inner of the board.  
The powersuply has now the green light but not so the board.  
I could install the USB driver and connect it to the repetier host.  But I cannot control the extruder manually.  The home button did move the motors.  Afterwards I read that when I don't have any endstops I can't use the homeing buttons..  
I also tried to flash the firmware as described in this forum but it fails and says the arguing.h file is missing.  
If I try  the g92 code,  the log says unknown command.. 


So..  What should solve my problem? 
Do I have to flash anything to the board or is it pre-flashed.  What does the red led mean?  How do I home my extruder? 

Thank you and sry for my English  :Smile:

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## Apollo

Hello Monokai!

I had the same problem as you but I figured it out!

First off, the red LED simply means that the board is on and operating properly. The color means absolutely nothing, so don't be worried.

Second, what version of windows are you running? That is the key to your problem!

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## Terrance

Hi everyone, I just finished building my Two-Up printer and plugged in the power cord.  I got the green LED on the power supply and the red LED on the red PCB, sound like this is normal.  Next I plugged the USB cable into my Windows 7 PC and it detected the device but failed to load any drivers.  I tried connecting it to my Mac and didn't see any indication that the Mac saw the device at all.  What am I missing?

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## Bobjimbob

I too am new to 3D printing and I just finished my own TwoUp printer. I hooked it all up and got a green light on the power supply box and a red one on my red printr board. I plugged it into my computer and although it did not install correct at first, I downloaded a serial install and got it to work after that. However, I can not get it to connect to RepetierHost. I set up the printer settings but when I go to hit connect I get a pop up saying "The connection failed with the following error: A device attached to the system is not functioning. Make sure your printer is connected, enabled, and connection data is set correct." I don't know what I'm doing wrong or where the problem is (did I mess up when installing the driver? Or does the problem go all the way back to the printr board? Is it just a RepetierHost problem?), but any help would be greatly appreciated. Thank you very much!

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## Bobjimbob

> Hi everyone, I just finished building my Two-Up printer and plugged in the power cord.  I got the green LED on the power supply and the red LED on the red PCB, sound like this is normal.  Next I plugged the USB cable into my Windows 7 PC and it detected the device but failed to load any drivers.  I tried connecting it to my Mac and didn't see any indication that the Mac saw the device at all.  What am I missing?


 Terrance it sounds like you have the same problem I had at first. Watch this video here https://www.youtube.com/watch?v=cR4-R_8tZhk and download the serial install file that is linked in the description. Follow what he says and it should work for you after that...

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