Running the Rambo at higher than 12v?

[pswindler]

So after looking at the rambo specs, it looks like it is fully designed to be run at higher then 12 v.

"Power
Three independent power rails for flexible input power configurations
Heated Bed, 15A 12-35V
Extruders + fans and logic, 5A 12-35V (fuse can be exchanged for up to 10A capacity)
Motors, 5A 12-28V (fuse can be exchanged for up to 10A capacity)"

I looked up the Nema 17 motors they are happy with higher voltages too. so the fans are be louder but a few more volts wont be detrimental to them.
So the only thing i am unsure of is the hot end accelerator board, could it handle 13 or 14 volts?

[Eric]

Great question!

Looking at their schematic: https://github.com/seemecnc/Machine_Ele ... CB_v5d.PDF

3.3V voltage regulator AZ1117CR-3.3TRG1 has a max input voltage of 15V
5.0V voltage regulator L78L05ABUTR has a max input voltage of 30V
And all the LED's use the input voltage as well, through current limiting resistors.
Also the fan.

So it was clearly designed for 12V operation. Feed it 24V and bad things will happen!

LED's will be a bit brighter, fan will work harder, but you can probably get away with 13 or 14V. At your own risk, of course!

[pswindler]

Thnaks, i need to get better at reading wiring diagrams, its like a foreign language to me! Ok so i will try to bump it up to 13.25 volts then, i feel comfortable with that. Unless someone really thinks that is a bad idea?

[DeltaCon]

Depends on what you are trying to accomplish with a bit higher voltage. The draw on your PSU will increase. Does your PSU have enough amps? I think for a faster heating bed this is no solution. Too little difference, and too much risk as some people already burn their Rambo heatbed connector even on 12V...

[pswindler]

i have the stock v3 power supply, yeah it is for the heat bed, my heat bed can hold 110 with an aluminum heat spreader right now, but i was just trying to get it up to temp faster. Also with all the talk of people getting separate power supply at like 24v, i figured if the connector holds up for them, then 13 v would be fine for me. is the a total misconception? how are people getting away with 15-24 v to the bed?

[Xenocrates]

The answer to how we get away with it is that we add an external switching device known as a Solid state relay. These range in price from 20-90$ (I recommend the 20$ Auber Instruments SSR). For those with a single power supply, typically the Rambo is fed from a converter. Now, since you want to run with a rambo board, and the V3 has an interesting architecture power wise, here is my suggestion: get a Meanwell power supply capable of feeding out at least 25A, I would suggest 30A, such as the Meanwell RSP-750-24 (183$), and put that in the base alongside the 29A 12v supply. Have an SSR switch power to the bed, and also run a power wire from it up the the stepper motor connector. That way the hotend and fans, which should include the logic onboard the accelerometer board doesn't end up fed too much power (Note that feeding the hotend 24V without replacing the cartridge will in fact end up with it having more power available than the heated bed originally, so it's a REALLY BAD IDEA). Connect the wires that used to power the heated bed to the control side of the SSR. Connect the heated bed to the 24V supply through the load terminals on the SSR. Consider pointing a fan at the SSR, especially if you use one other than the Auber instruments one. Do not buy any of this on Ebay, or Amazon for that matter, it is likely mis-marketed and might fail/catch fire/explode (Ranked in order of likeliness) if you attempt to use it.

[Eric]

(Note that feeding the hotend 24V without replacing the cartridge will in fact end up with it having more power available than the heated bed originally, so it's a REALLY BAD IDEA).

While you are not wrong, the 12V cartridge is one component that might survive that treatment. The REALLY BAD IDEA part is because it'll blow the 3.3V regulator, which will break the accellerometer. Also the hotend LED and fan will probably die in a matter of minutes. The HE280 can't take 24V! Someone will blow one before the month is out, I bet!

V3 is new enough I suspect most are still stock at this time. Also I gather the newest rev onyx heats better than previous models, so the need is reduced.

[Noircogi]

Before doing a PS upgrade on my V3, I first turned the voltage up to around 14.5. There's a voltage drop in the control FETs and the wiring to the bed, so that was the value which resulted in just under 15A on the bed fuse circuit.

It mostly worked, but sometimes, the system would not power on correctly and of course the fans ran fast. I recommend you not go over about 13.5V if you do that.

In the end, I put a 24V supply in the base, but turned it down to 20.5V to reduce the current draw to the bed. Getting two power supplies in the base turns out to be a tough fit due to the tower mounts, so I added a 12V 20A regulator to power everything but the bed from the 24V supply. I'm using a Crydom SSR, but I believe the Auber is a much better bargain.

My Onyx is 0.92 ohms btw. I measured it two different ways, one direct with a high-end fluke meter and one indirect by measuring voltage and current.

The HE280 has plenty of power at 12V and heats really fast. On the Max V3, the only reason to increase voltage is the bed heater.

I just added a post here with the info on my power supply upgrade: http://forum.seemecnc.com/viewtopic.php?f=35&t=10904

[pswindler]

cool thanks all! i think i will just up the voltage to 13, and call it good. after insulating the bottom of the bed like crazy, and putting a sheet metal separator between the power supply fan and the base fan( so i am not actively cooling the base, only activly cooling the power supply) it can hold 120, but after i put in my aluminum heat spreader, the actual temp of the base is higher and more accurate. so now i can barely hold 110 while printing. i just want to make my 110 goal more reliable. so that is why i only need a very small increase in performance. its probably the best preforming stock restock max bed there is right now. because i am stopping almost all heat loss from anywhere but the open top. I will bump it to 13 and report back.

[Xenocrates]

(Note that feeding the hotend 24V without replacing the cartridge will in fact end up with it having more power available than the heated bed originally, so it's a REALLY BAD IDEA).

While you are not wrong, the 12V cartridge is one component that might survive that treatment. The REALLY BAD IDEA part is because it'll blow the 3.3V regulator, which will break the accellerometer. Also the hotend LED and fan will probably die in a matter of minutes. The HE280 can't take 24V! Someone will blow one before the month is out, I bet!

V3 is new enough I suspect most are still stock at this time. Also I gather the newest rev onyx heats better than previous models, so the need is reduced.

I agree that that will likely survive. It's having that much power pumped into the hotend would have resulted in an interesting and rapid meltdown on the old hotend, although it would likely just promptly pop the thermal fuse from either overcurrent or heat on the new models. I would also worry about it potentially softening the effector. Admittedly, I haven't looked much into the design of the probe board, so I can't say if you could power the heater and board separately. I do like to imagine that a 160W hotend would challenge even my temperature sensor as far as max temperature attainable (briefly).