Heated Bed failed (Original Prusa i3 Kit with Mini Rambo 1.3a)
Hello all,
I've an Original Prusa i3 Kit which I assembled and has given me a lot of care free printing. However it has recently failed because the heated print bed is not being heated at all. The controller board, a Mini Rambo 1.3a, isn't putting out Voltage on the headed bed connection, so the problem appears to be in the controller board. All fuses are good. I wonder should I upgrade the control board to something else?
RE: Heated Bed failed (Original Prusa i3 Kit with Mini Rambo 1.3a)
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Chuck H
3D Printer Review Blog
RE: Heated Bed failed (Original Prusa i3 Kit with Mini Rambo 1.3a)
Bad connector on the heated bed wire connecting to the controller board. Only making one contact 🙁
RE: Heated Bed failed (Original Prusa i3 Kit with Mini Rambo 1.3a)
Got it sorted desoldered the current connector. I've had difficulty with it before. It's handling a bit of current and that plug in design is convenient but not reliable. Replaced with screw terminal blocks and I'm up and running again. Hopefully the screw terminals make a more solid connection.
RE: Heated Bed failed (Original Prusa i3 Kit with Mini Rambo 1.3a)
Resurrected a printer left by my son. Fixed the heat bed problem. The two part Molex 3953x connectors (header and terminal block) which provide connection to heat bed are overheating and melting internally. I figure current to heat bed is in excess of 10A. I replaced the connector with original Molex connectors and had the same problem happen again. I finally replaced the connection with an inline automotive connector (16 AWG type) and problem solved. I have printed many face shield frames in PETG material without issues. The curious thing here is that the same current going to the heat bed must come in via the power supply connectors which use the same Molex 3953X connectors. This connector does not melt.
WARNING: Repair requires removing the RamBo board Molex header connector which requires soldering experience. This is not trivial.
Rambo header connector is Molex 3953x series with part number 0395311004 available from Digi-Key (pn WM7839-ND). The terminal block I got from V1 Engineering (sorry lost the PN) but Digi-Key also can supply. The inline automotive connector I got from Amazon - cheap connector. Make sure its a 16AWG wire size because of the current load (16AWG can handle 15A).