Skip to main content

How To: Run Compaq ESP127 power supply model: PS-5501

I got ESP127 power supply from an old Compaq server some time ago, with intention to use it as my RepRap printer power supply. But I couldn't find any useful information on the internet on how to get it to power on. 
Today, I've decided to grab my multimeter and play with it to see if I will be able to get it to work. By default when you plug the power cord to it, the cooling fan will start spinning but the green LED at the back will stay off and there will be no voltage (or almost no voltage) on any of the power rails +3.3v, +5v, +12v. This power supply +12v rail can handle 25 amperes which makes it perfect for a reprap. 
After an hour or so... I saw a green light ;)

 I've soldered terminal socket to the 12v pads to make it more portable and easy to setup.


  1. hi,
    do you now also how to get out -12V,+5V and 3.3V?

  2. I'm not sure about -12V but 5v and 3.3v should be available at the bottom pads, just measure the voltage between ground and the pads

  3. Thanks, i got the same one for a project, i see you soldered/shorted in 3 places (2above, 1 below), in a normal ATX you only need to short 1. are those 3 shorts really needed? or just one? just making sure, thanks, don't won't to blow the thing up :)

    1. It was a while ago.. but I'm pretty sure these 3 shorts are needed, I had the backplate/edge connector for this psu and I have figured out the correct (hope so ;) )pinout from it.. I have 3 of these running without issues since almost 2 years :)

    2. Thanks from my prusa i3 whit new power supply ! :)

  4. Hi I have the same power suply and , as you , my green LED is not on but the fan is , how did you fix it ?


Post a Comment

Popular posts from this blog

Ramps 1.4 LCD with Marlin firmware

Small upgrade for my Prusa Air 2 reprap :).. I got this pcb with rotary switch and LCD from ReprapDiscount, they sell really nice looking and quality Ramps kits for quite cheap. Apparently they sell quite a lot of these LCD boards.  To get the LCD board to work you need to uncomment kollowing line in your Configuration.h file // The RepRapDiscount Smart Controller // #define REPRAP_DISCOUNT_SMART_CONTROLLER Polish translation was done in Google translator probably ;), 'Ubity'? LoL Starting to love Marlin firmware especially with the ReprapDiscount smart controller. All the language  translations are in the file language.h, choose your language and voila :). Of course some of the translations aren't perfect. // Languages // 1  English // 2  Polish // 3  French (awaiting translation!) // 4  German // 5  Spanish // 6  Russian // 7  Italian // 8  Portuguese #define

SLA LCD / DLP Resin 3D Printer

It's been a while since my last post, finally got some time for a short update. I have decided to try SLA type printer as these have much higher resolution comparing to FDM printers. I'm a hands on person so instead of buying one I've decided to design and build one by myself, it's always a fun and a good way of learning new skills. The main goal is to build an LCD-based 3D printer that will work with both UV and Daylight resins. For now, I will try to get it to work only with daylight curing resins as the iPad LCD won't really pass anything below 450nm. Here are some renders: It's designed around iPad 9.7" retina LCD. I'm planning to add LED array underneath the screen (460-465nm epileds) and remove backlight diffusers and the polarizer. I'm currently working on FEP film VAT.