heatbed problems
Hi all,
i'm having issues with my heatbed. I got a mk3s kit wich i assembled and when i want to get started i allways fail with heatbed warming test.
I allready had a look around for sollutions and got in contact with the online support.
after rechecking everything 5 times,and testing out all i could think of with a multimeter we came to the conclusion it was probably a faulty rambo board.
I got my replacement and i installed it but to no avail because i still get the same error wit hthe selftest (and if i try to heat the bed up otherwise aswell). Is there anyone who had a problem like this out of the box ?
Maybe it is the bed itself because the led on the bed doesn't light up?
Anyone any ideas?
Bruno
RE: heatbed problems
If you ohm the bed from the EINSY end of the cable, what's the resistance you see?
RE: heatbed problems
nothing :/
Bruno
RE: heatbed problems
The LED on the bed only indicates that there's voltage being delivered to the bed - and that the voltage has the correct polarity to light the LED. The bed itself could be open circuit and the LED wouldn't care. On the other hand, if the wires are reversed, the bed itself doesn't care about the polarity of the voltage; if it's good, it will heat up even if the LED thinks the voltage is backwards. Or, in my case, the LED itself was defective and would never light up even though the bed was heating up just fine.
So start from the bed itself. Disconnect the wires from the Einsy. Use the ohmmeter on the bed copper pads. The resistance should be just a few ohms. Not "infinite", not Megohms, or Kilohms, but in the single digits of ohms. Then make sure that your wires are securely attached to the bed. If you measure the resistance from one of the copper pads on the bed to the other end of the wires, one wire at a time should be very close to zero ohms (while the other is infinite). Make sure that both wires have zero ohms. If you can't get a zero ohm reading, then be suspicious of the crimping job where the connecting lug is attached to the wire. If both wires are good, then you should be able to get basically the same ohm reading from the Einsy end of the wires as you got from the board itself.
If the heat bed is good and the wires are good, then make sure you have applied reasonably strong torque to the screws that hold the lugs onto their respective terminals. You should not be able to move the lugs at all once they've been tightened onto their terminals.
And, of course, be sure you are on the correct terminals. It's crowded in the Einsy case and easy to make a mistake.
What is the thermistor reading when there's no heat on the bed? If it's not pretty close to room temperature, then maybe there's a problem with the thermistor wiring (for example, where it's plugged into the Einsy). If you call for heat on the bed and the thermistor doesn't change, try touching the bed to see if it's warming up. If it's warming up but the thermistor doesn't indicate warmth, then the problem is definitely in the thermistor sensing and not in the heater.
RE: heatbed problems
No resistance shown (infinite) when measuring from the EINSY side means:
1) The bed could be bad. Test continuity across the two etched copper traces.
2) One or both of the connection screws is not making contact with the bed circuit board. Test continuity from the screw to the etched copper trace under the screw.
3) One of the crimps on the wires can be bad - open. Test continuity of each wire, ohms from EINSY side to bed connection screw lug.
