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Low voltage at rambo heatbed output  

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Dandelo
(@dandelo)
New Member
Low voltage at rambo heatbed output

Hi,

I got a "Bed Thermal Runaway" error during a print and since then the heatbed does not heat up any longer.
Voltage at the heatbed power supply output on the rambo is only 1.9v, same on the soldered connections at the back of the board. (hotend voltage is 12v)

Does this mean the rambo board needs to be replaced? Any other possible solutions?

thank you for your help
regards
Marlon

Posted : 05/02/2019 7:11 pm
Olef
 Olef
(@olef)
Prominent Member
Re: Low voltage at rambo heatbed output

Your heatbed fuse may have blown, pull it and check it with a meter.

Posted : 18/02/2019 7:53 am
Dandelo
(@dandelo)
New Member
Topic starter answered:
Re: Low voltage at rambo heatbed output

thanks for your help!

Fuses are working. Replaced the Rambo, back to printing...

regards Marlon

Posted : 22/02/2019 9:51 am
Dandelo
(@dandelo)
New Member
Topic starter answered:
Re: Low voltage at rambo heatbed output

update: the new board showed the same issue after ~10 hours of printing: Bed thermal runaway and only 2V at heatbed output. I contacted Prusa via live chat, they told me to try switching the position of the psu cables (ones that go from psu to rambo). And voilà heatbed is working again with full 12v. Maybe it was only some loose connection / dust, so the old board probably was not broken after all...
Thanks to David at Prusa Live Chat, great support!

picture of Power input on the board (left side on the bottom, just swap position of upper/lower cable):
https://d17kynu4zpq5hy.cloudfront.net/igi/prusa3d/UZGtDxDLODaR2e5q.huge

Posted : 27/02/2019 6:07 pm
ian.s13
(@ian-s13)
Active Member
Re: Low voltage at rambo heatbed output

How does one access Live Chat? I've never even received an email response to Support questions. Who knew there was Live Chat?

Ian
Toronto

Posted : 11/03/2019 7:20 pm
vintagepc
(@vintagepc)
Member
Re: Low voltage at rambo heatbed output


How does one access Live Chat? I've never even received an email response to Support questions. Who knew there was Live Chat?

Ian
Toronto

sign into the prusa store and it will appear in the bottom right as a tab.

It is mentioned on the "new user guide" which you did read, right? 😉

https://www.prusa3d.com/new-user-mk2s/

Posted : 11/03/2019 7:35 pm
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