Oddball ramps power issue.
June 29, 2015 12:39AM
All right, I am trying to understand why this issue occurred. I and the young man who helped me and identified the cause, but we were not able to understand the WHY of it.

Here is the issue, we had voltage of 12.36 from the power supply to the RAMPS, same on the headers at the power supply. The Ramps however was not powering up, we were simply not able to get power past the connector. We checked the cable and there were no shorts, we checked ampage and we we getting over 14A (the wires got to hot to continue holding them there.) However no juice to the board. The power cables were 16 GA Stranded copper, roughly 1M in length.

We swapped a set he had from his printer to mine, they were either 18 GA or 20 GA Stranded at about 600mm, and presto everything had juice. There seems to be no rhyme or reason why this is happening, my cables tested out fine, any thoughts?

Thank you in advance for reading and replying.

Re: Oddball ramps power issue.
June 29, 2015 02:32AM
To power the Ramps, you need a arduino underneath. The Arduino provides 5V from the 12V it gets from Ramps/PSU.
If you havenĀ“t connected a arduino or the power connections between the two boards are faulty/intermittend, you see nothing.
Re: Oddball ramps power issue.
June 29, 2015 03:03AM
O Lampe,

Sorry I thought it was an assumed that I would have the Mega as part of that picture (which was clearly talking to the laptop, we had the current Marlin firmware loaded.) It is my fault for not being clear. To be exact I had the whole package there, the Mega, the Ramps, the drivers all the connections were properly made. As stated it worked once we switched cables the electronics powered up. Which still does not explain the why.


Re: Oddball ramps power issue.
June 29, 2015 06:23AM
I'd be looking at the connectors. Not all connectors are the same, and it's possible you've got a dodgy set.

Q: How did you check ampage (the current)? You need to put your meter in series with the board to do that, and there should only be current drawn if it's working. If you've got one of the connectors the wrong way, you will get a short, which might explain it. If you get both the wrong way, diode D2 will hopefully protect your board from the reverse voltage, but will probably die in the process.
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