<p>From your fault description of printer logic board losing power when endstops are released it sounds to me like those endstops are shorting VCC to GND when not pressed. That the fault also goes away when the endstops are unplugged reinforces this.</p>

<p>I guess the logic board has its own protected regulator because otherwise you would be shorting out the power supply and that would also turn itself off after likely causing a lot of damage to the logic board.</p>

CC BY-SA 4.0
2019-11-22T14:13:19.070Z
2019-11-22T14:13:19.070Z
r_ahlskog
<p>It ended up I had like super cheap endstops that were actually shorting VCC to GND, as suspected by r_ahlskog. Just bought other ones and now it's working fine.</p>

CC BY-SA 4.0
2019-11-22T14:19:08.627Z
I'm starting to think that those switches were just wired wrong for your printer. Should I try and edit in that into my answer.
r_ahlskog
CC BY-SA 4.0
2019-11-22T23:19:45.027Z
it is relevant in context qith this question if your endstops are NO or NC. It sounds they are NC.
Trish
CC BY-SA 4.0
2019-11-22T10:13:14.297Z
2019-11-22T14:42:22.597Z
2019-11-22T14:42:22.597Z
Cobactan
<p>Recycling a Robin Nano board to build a 3D printer using an old computer PSU (300 W), it only boots on when I have no endstops pugged in at all or if I trigger all the ones I have plugged. At the moment I release them the screen goes off (but the fan of the PSU is still on). Does anyone have any clue about what's going on ?</p>

CC BY-SA 4.0
2019-10-20T18:59:52.153Z
Welcome to 3dPrinting.SE! What controller are you using? Have you double checked to ensure you've attached everything correctly? Have you tried it without anything plugged in (no endstops or motors)?
Pᴀᴜʟsᴛᴇʀ2
CC BY-SA 4.0
2019-10-20T19:15:37.690Z
I doubled and tripled check the wiring. When nothing is plugged it goes on properly. Controller board is a Robin nano board.
Cobactan
CC BY-SA 4.0
2019-10-20T19:30:19.193Z
Sounds like the endstop switches are shorting VCC to GND when not pressed. I guess the logic board has its own 5V regulator because I imagine the computer PSU would happily melt cabling or weld the switches.
r_ahlskog
CC BY-SA 4.0
2019-10-20T19:35:23.003Z
I used the nano board previously on a printer with a 24 v psu without any endstops related issues. The nano is supposed to manage both 24 and 12 volts. I doubled checked on the endstops boards to make sure signal, ground and VCC are corresponding.
Cobactan
CC BY-SA 4.0
2019-10-21T15:35:02.563Z
In line with @r_ahlskog 's comment - either that or your board is expecting NO switches but yours are somehow N/C switches.
Carl Witthoft
CC BY-SA 4.0
2019-11-22T04:16:52.887Z
@R_asidkog your comment is good. It may not be right,  but it is good. I can't upvote it because it is not an "answer". Could you submit it as an answer?
cmm
CC BY-SA 4.0
2019-11-22T10:12:19.293Z
It ended up I had like super cheap endstops that were actually shorting VCC to GND. Just bought other ones and now it's working Thanks all !
Cobactan
<diy-3d-printer><endstop>
My DIY printer only boots when all my endstops are triggered. Why is that?
Cobactan
# My DIY printer only boots when all my endstops are triggered. Why is that?

(Asked by: username_0 on 2019-10-20)

Recycling a Robin Nano board to build a 3D printer using an old computer PSU (300 W), it only boots on when I have no endstops pugged in at all or if I trigger all the ones I have plugged. At the moment I release them the screen goes off (but the fan of the PSU is still on). Does anyone have any clue about what's going on ?

**Tags:** diy-3d-printer, endstop
> **Comments:**
> **username_1**: Welcome to 3dPrinting.SE! What controller are you using? Have you double checked to ensure you've attached everything correctly? Have you tried it without anything plugged in (no endstops or motors)?  
> **username_0**: I doubled and tripled check the wiring. When nothing is plugged it goes on properly. Controller board is a Robin nano board.  
> **username_2**: Sounds like the endstop switches are shorting VCC to GND when not pressed. I guess the logic board has its own 5V regulator because I imagine the computer PSU would happily melt cabling or weld the switches.  
> **username_0**: I used the nano board previously on a printer with a 24 v psu without any endstops related issues. The nano is supposed to manage both 24 and 12 volts. I doubled checked on the endstops boards to make sure signal, ground and VCC are corresponding.  
> **username_3**: In line with @r_ahlskog 's comment - either that or your board is expecting NO switches but yours are somehow N/C switches.  
> **username_4**: @R_asidkog your comment is good. It may not be right,  but it is good. I can't upvote it because it is not an "answer". Could you submit it as an answer?  
> **username_0**: It ended up I had like super cheap endstops that were actually shorting VCC to GND. Just bought other ones and now it's working Thanks all !  

---

## 2 answers

### Answer by username_2 on 2019-11-22. Score: 3

From your fault description of printer logic board losing power when endstops are released it sounds to me like those endstops are shorting VCC to GND when not pressed. That the fault also goes away when the endstops are unplugged reinforces this.

I guess the logic board has its own protected regulator because otherwise you would be shorting out the power supply and that would also turn itself off after likely causing a lot of damage to the logic board.


---

### Answer by username_0 on 2019-11-22. Score: 2

It ended up I had like super cheap endstops that were actually shorting VCC to GND, as suspected by r\_ahlskog. Just bought other ones and now it's working fine.

> **Comments:**
> **username_2**: I'm starting to think that those switches were just wired wrong for your printer. Should I try and edit in that into my answer.  
> **username_5**: it is relevant in context qith this question if your endstops are NO or NC. It sounds they are NC.  

---

