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Heat Bed pre heat error - time for a new board?  

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skipZero
(@skipzero)
Active Member
Heat Bed pre heat error - time for a new board?

So it seems that I'm not getting any voltage to my heat bed any longer... Ive checked the bed voltage in, the bed voltage out, both at the board and at the bed, I've checked the resistance across the board, while not plugged in, I've flipped the wires coming into the board... I've checked everything. At least I think I have... I've flashed all firmware from 3.7 down to 3.4.1 and didn't have any luck there, either. 

I'm posting to see if anyone else has any ideas or anything I could possibly do to salvage this, else I'm going to have to order a new board. 

And that brings me to another question: If I'm to replace my board, is there any other boards that anyone would recommend for a MK2.5? I've got the MMU2 with the /s upgrade just waiting for me to be able to print the pieces for it. So it'd have be compatible with that. I'm not sure if the two boards talk to each other or how much they do if so, so not sure if that chains me to the Prusa RAMBos... The more I think about it, the more I think I'll just get another rambo mini and figure out other ways to upgrade the drivers to Trinamic 2130 drivers.

tl; dr:
I think my rambo mini is toast and tested a bunch of things and wanna know if it is, or might be salvageable. If not salvageable, what are my options as far as a replacement. It'd be nice to get the TMC 2130's but also fine to keep it stock, if it means being able to use the MMU2 unit.

Posted : 13/05/2019 2:51 am
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(@)
Illustrious Member
RE: Heat Bed pre heat error - time for a new board?

Did you check the fuses?

Posted : 13/05/2019 4:07 am
skipZero
(@skipzero)
Active Member
Topic starter answered:
RE: Heat Bed pre heat error - time for a new board?

Yes. Several times as I tested other things. 

Posted : 13/05/2019 2:42 pm
skipZero
(@skipzero)
Active Member
Topic starter answered:
RE: Heat Bed pre heat error - time for a new board?

I'm gonna take it that no one has anything to add and that the board isn't ever heating up the bed again so I guess I'll find me a new RAMBo mini and hopefully get the printer back up on it's feet!

Posted : 14/05/2019 3:45 am
PJR
 PJR
(@pjr)
Antient Member Moderator
RE: Heat Bed pre heat error - time for a new board?

My thought:  It is very unlikely that the RAMBo is dead.

It did happen to me once, on the Mk1, when one of the bulldog clips holding the glass build plate decided to jump into the open top of the RAMBo case on that printer and short some pins on the MCU 🙁

Did you check the voltage of the heater output on the underside of the board?  It maybe that the heater plug/socket has burned and a simple solution would be to solder new tails onto the underside.

 

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 14/05/2019 8:39 am
vintagepc
(@vintagepc)
Member
RE: Heat Bed pre heat error - time for a new board?

Have you checked the power supply outputs? The bed is a separate rail so the rest of the system still works even if that one is dead.

Posted : 14/05/2019 10:53 am
skipZero
(@skipzero)
Active Member
Topic starter answered:
RE: Heat Bed pre heat error - time for a new board?

yup, I did and no, or at times very little, power from the bed out and it's 12.3v going in on both inputs...

Posted : 14/05/2019 11:05 am
skipZero
(@skipzero)
Active Member
Topic starter answered:
RE: Heat Bed pre heat error - time for a new board?
Posted by: PJR

My thought:  It is very unlikely that the RAMBo is dead.

It did happen to me once, on the Mk1, when one of the bulldog clips holding the glass build plate decided to jump into the open top of the RAMBo case on that printer and short some pins on the MCU 🙁

Did you check the voltage of the heater output on the underside of the board?  It maybe that the heater plug/socket has burned and a simple solution would be to solder new tails onto the underside.

 

Peter

I haven't checked under the board, but it doesn't seem to be loose or otherwise disturbed. I have melted a connector from the board to the heat bed in the past, so I'll double check that. still, I don't think that'll help, but worth a try, definitely. Thanks Peter!

 

Posted : 14/05/2019 11:08 am
John
 John
(@john-15)
Active Member
RE: Heat Bed pre heat error - time for a new board?

Hi

I have recently had a heat-bed failure.  I have tracked it down to the output MOLEX connector and plug,  One of the pins on the outlet to the bed is badly burnt.  So bad that the plug was distorted and hard to disconnect. 

I am searching for info on de-soldering the MOLEX header from the Rambo board.  The solder doesn't want to melt and stick to my de-solder wick.

Posted : 10/04/2020 10:55 am
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