Dual Power 12v and 24v to Einsy RAMBo?
Request for comment please from the advanced tinkerers.
I have a Mk2S Haribo modded printer and I have purchased a Mk2.5 upgrade kit for it. My problem is I cannot ignore the Einsy RAMBo and its new features not least of which how quiet the Mk3 is. So I have bought a 24v PSU and Einsy RAMBo to bring my 2S up to Mk3 spec.
First setback is the Y Carriage on the Mk2S and the Mk3 are different and the two heatbed PCB 's have differing amount of mounting points with differing hole centres. So to go fully Mk3 I would need a 24v heatbed and a Mk3 Y Carriage - or I could consider a hybrid dual power machine with both 12v and 24v power supplies which I already have.
The Einsy RAMBo shows different inputs for the board power and the bed power. On the right in blue we have a pair of main power inputs, then a pair of bed power inputs, then the bed output pair -
So I am thinking of using both PSU's and supplying 24v to the Power Input pair, and 12v to the Bed Power Input pair. In this way I can drive the Einsy with the full 24v but still utilise the Mk2.5 12v bed and original Y Carriage.
Do you think this will work, or would it be better to power the Einsy fully with 24v but use a MOSFET board to switch 12v to the upgrade kit heatbed?
Any input gratefully received 🙂
Re: Dual Power 12v and 24v to Einsy RAMBo?
Anyone? 🙂
Re: Dual Power 12v and 24v to Einsy RAMBo?
Rambo specs, as per http://reprap.org/wiki/Rambo :
Power
Three independent power rails for flexible input power configurations
Heated Bed, 15A 12-24V (version earlier than 1.1 limted to 14A 16V due to fuse rating, see rambo_development for hacks)
Extruders and fans, 5A 12-24V (fuse can be exchanged for up to 10A capacity) 10V-26V input voltage
Motors, 5A 12-24V (fuse can be exchanged for up to 10A capacity) 10V-26V input voltage
So I don't think that powering bed wit 12v should give any issue, since the power rails are independent. On the schematics they are also pretty much separated, see the "mosfet" part in the middle.
Re: Dual Power 12v and 24v to Einsy RAMBo?
Thank you Pavlo, much appreciated 🙂
Re: Dual Power 12v and 24v to Einsy RAMBo?
Do you have been successful? I am planning to do the same...
Re: Dual Power 12v and 24v to Einsy RAMBo?
I agree, according to the board schematic, it's no problem.
There are a number of posts on board/frame grounding, but I think much of it is bogus.
Normal practice for industrial electronics is to connect the board ground to the frame (usually via the mounting holes).
In the printer, of course the box is plastic. Some people have reported issues with resets that were resolved by grounding the board to the frame.
That makes sense and the board is fine with that, though it won't matter if you have external supplies (not bolted to the frame).
In that case, I would run a separate wire from the board mounting hole to the frame of the external power supply.
Why it matters for the MK3 and not for the MK2 I don't know. Maybe some subtle difference in ESD sensitivity.
The USB connection is fully isolated from the rest of the electronics, so grounding the board or not doesn't matter to the USB.
One thing to remember is that the frame parts are anodized or powder coated--neither finish is conductive!
On my printers (MK2 and MK3), I can't measure continuity between screws bolted into the frame--the coating on the threads much be thick enough to insulate them. Pretty unexpected, but don't assume everything is connected as expected without measuring it.
Tim
Re: Dual Power 12v and 24v to Einsy RAMBo?
As I could not find a definitive answer and I didn't feel like burning out an Einsy, I used an external mosfet. I supply 24v to the Einsy on both pairs of PSU cables but I supply 12v to the external mosfet power input, hence feeding the 12 to the bed. It works fine, and it works well.
Re: Dual Power 12v and 24v to Einsy RAMBo?
So in order to do this i would need to purchase the following
Meanwell 24v PSU (would i be safe with 150w as its only driving steppers and thermistor or is it not worth the risk)
Heatbed Mosfet (amazon for $8)
Wiring and Crimp Ends
Einsey Rambo (from prusa)
Im guessing we would need a new noctua and cooling fan?
Just trying to do the math to see if its worth digging into more.
Thanks
Re: Dual Power 12v and 24v to Einsy RAMBo?
A new hot end heater cartridge...
also both inputs are separate, you don't need an external mosfet. the board will take 12v to 24v range on either voltage input.
Re: Dual Power 12v and 24v to Einsy RAMBo?
Yea that makes sense. Probably not worth it at this point. I have already installed z braces to a paver and have an enclosure which together makes it pretty silent. I was just hoping to improve surface finish a bit which as of this point is hit or miss it seems with the mk3.
Re: Dual Power 12v and 24v to Einsy RAMBo?
What type of connector is the power panic board connected to the Rambo board?
Jim