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kevin-osborn

Don't try this at home: Power supply mod

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NOTE: THIS PROJECT REQUIRED MESSING WITH HIGH AMPERAGE ELECTRICITY, AND THE DANGER OF FIRE IS HIGH! DO NOT ATTEMPT!!! (Unless you absolutely know what you are doing.)
I have a modified UM2 (olsson, Meduza/Rober feeder, 1.75mm conversion) which has been working well for about 4 years.

A month or so ago, my power supply just stopped working, 0V, no blue light. The printer still worked if I plugged my UM3 PSU in.

I needed to keep printing, and I happened to have a high amp 24V  PSU that I'd been saving for a CNC project. After opening the brick and determining that there was nothing I could fix, I removed the output wires/cable, soldered some leads to the end and connected to my power supply.

Mostly because the replacement is pretty expensive, and the new supply was working, I decided not to order a new one.

the only downsides were that the new powersupply wasn't very portable, and was very loud (it has a fan)

During this, @gr5 told me that these supplies sometimes they come back to life when you let them sit over night. Sure enough I plugged the brick back in and it was working again. I didn't trust it enough to reverse my "borrowing" of the cord so I came up with a different solution: install a female barrel jack in the brick, and also on the new power supply. Putting a plug on the cord, I could swap back and forth as I see fit. I designed the adapter in Autodesk Fusion360 (it was pretty simple)
 

IMG_1771.thumb.jpg.8b92ba347296c51d60babfbb4b57d01e.jpgIMG_1768.thumb.jpg.84820fbdace1d0617ae2e8dbd4be69c9.jpgIMG_1770.thumb.jpg.8dd71f2b2afbd44b839b81b95a8b0a9a.jpgIMG_1773.thumb.jpg.d1739b70e330c434c31d51f12e7eabf4.jpg

It had to be printed with support on my UM3. BTW, That breakaway material is the bomb!

Speaking of which, my cautionary tale:
I've been cleaning my office and I couldn't find any heavy gauge wire. I decided to snipe some from a pc power supply harness, and well, I should have trusted my instinct, as it looked a little weedy once I stripped it. (thick insulation, but the wires weren't so thick.)

As a result, the first time I powered on, the printer came on fine, but when I drew serious current (bed heating up) by starting a print, the wires vaporized. Fortunately for me nothing caught on fire (though the smoke detectors did go off). I ran to my local electronics store and got some 16 Ga wire. and everything has been running fine.

If you do attempt this, (please don't) I think you should use at least 18  gauge stranded wire. Also, the PCB isn't the greatest quality and it's very easy to lift a trace pulling the original wires out when desoldering.

The design will be up in youmagine https://www.youmagine.com/osbock/designs

 

Edited by kevin-osborn
fix text flow with pictures
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