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No power, buddy board and LCD blink periodically  

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dlm3
 dlm3
(@dlm3)
Active Member
No power, buddy board and LCD blink periodically

On my first power-up (and all since), the XL does literally nothing other than causing four LEDs on the buddy board and one on the LCD to blink periodically.

I spent many hours with support and have disassembled much of the back of the unit to find that the left power supply is not functioning; the right supply is putting out 24Vdc as expected.

A little digging into power supply features revealed that some supplies go into a "hiccup" mode where they attempt to power up into a short, then shut down again before damaging themselves. That would seem to explain the behavior of the buddy board and LCD panel.

What I don't know how to do is find where that short might be occurring. A schematic would be helpful. 

Inspecting the power connections at the buddy board shows nothing interesting. What I can't see is what is inside the power distribution unit. On the assumption that everything tested OK before it left the factory and something was rattled free in transit, it seems to me there's probably a short in the power distribution unit somewhere. 

Does anyone have insight into what might be going on? 

Best Answer by dlm3:

Problem solved. The power supply terminals were miswired, shorting the power supply and causing it to go into "safe" mode. The correct wiring is the same as on the MK4 photo earlier in this thread - both red wires go to the V+ terminals, both black wires go to the V- terminal.

Machine is now calibrated and running properly.

Posted : 04/12/2023 5:38 pm
dlm3
 dlm3
(@dlm3)
Active Member
Topic starter answered:
RE:

Update: Took this photo of the wiring to the left power supply after removing the PDU. Does anyone have a photo of the wiring for a machine that works? (Prusa Support is working on it) I'm thinking it may be miswired since the power supply functions just fine with the loads disconnected and the colors of the wires don't look correct vs. the markings on the power supply (V+/V-)

This post was modified 3 months ago by dlm3
Posted : 09/12/2023 9:47 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
RE: No power, buddy board and LCD blink periodically

that doesn't look right to me. but I don't have an XL to compare with.

this is how I would expect it to look!
regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 09/12/2023 10:55 pm
dlm3
 dlm3
(@dlm3)
Active Member
Topic starter answered:
RE: No power, buddy board and LCD blink periodically

That sure looks more correct. Hopefully Prusa gets back to me and confirms.

Posted : 10/12/2023 2:38 am
JoanTabb
(@joantabb)
Veteran Member Moderator
RE: No power, buddy board and LCD blink periodically

Have you had a chat with prusa. And referred to this post?

Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 10/12/2023 11:05 am
dlm3
 dlm3
(@dlm3)
Active Member
Topic starter answered:
RE: No power, buddy board and LCD blink periodically

I talked to Prusa Support yesterday before you provided the photo. They didn’t have any reference material that could answer the question.

Posted : 10/12/2023 2:52 pm
dlm3
 dlm3
(@dlm3)
Active Member
Topic starter answered:
RE: No power, buddy board and LCD blink periodically

Problem solved. The power supply terminals were miswired, shorting the power supply and causing it to go into "safe" mode. The correct wiring is the same as on the MK4 photo earlier in this thread - both red wires go to the V+ terminals, both black wires go to the V- terminal.

Machine is now calibrated and running properly.

Posted : 27/12/2023 6:49 pm
BaconFase liked
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