Rambo problem -> Anyone selling 32 bit controller boards locally?

[Julian Rendell]

Background in case anyone else has seen (and fixed) this:

One of our taz 4 printers keeps having intermittent skipping on the y-axis. Made the time to try and debug this. It uses a Rambo board. Looks like the digipot voltage reference for the drivers is not working. Tried stock firmware and latest marlin, tweaking SPI speeds leads to the same .74V reference voltage for all the drivers... and each has a different setting in the firmware. (And I've disabled eeprom settings storage.)

At this point a replacement Rambo board is about the same price as a smoothie board or duet. 

I'm thinking of replacing with one of duet, smoothie, or azteeg.

Duet looks to be almost drop in replacement - can run from single 24v supply. 

Smoothie requires an additional regulator- which will probably cost me extra shipping to Vancouver island. 

Need to look more into azteeg...

By chance, has anyone else had this issue? 

And does anyone have a board they want to sell? 

Thanks 

Julian

Julian

[Edward Simpson]

Hi Julian,

I've been running a Duet 0.8.5 on 24V for the past year, works just fine :). As for the Azteeg, I've got one of Panacutt's other Smoothie boards running my primary printer, it's the Re-ARM, basically a Smoothieware CPU in a Mega 2650 form factor board that plugs into the bottom of a Ramps 1.4 board, it's available in Canada here for about $80, might be a slightly cheaper option since a basic ramps kit is only about $40 on Amazon, assuming that your old Huxley isn't Ramps based :) As for the stepper glitch, have you tried using the M500/502 gcodes to overwrite the EPROM when you had Marlin loaded? Only other suggestion that I can make is to try pointing a big fan at the board for some extra cooling, that sometimes fixes the problem if it's an overheating glitch.

Edward

[Julian Rendell]

Thanks Edward-

You seem to always be discovering new suppliers that I’ve not heard of :-)

Although the Re-Arm is good to 30V, my understanding is that all the RAMPS boards are max 12V input without mods. Lulzbot’s electronics are 24V.

Do you know of any 24V ready RAMPS boards?

I’m still trying to work out if it’s overheating, or a lack of power. Cooling should be good- case has a pretty good built in fan. I’ve also improved the cooling further by removing the heatsinks. Definitely a case of a little knowledge being dangerous: I put the heatsink ON the chip. The type of chip package used on Rambo is thermally connected to the copper on the PCB, so the heatsink should go on the back of the board!

But due to the digipot issue on my RAMBO I couldn’t adjust Vref. But last night I managed to successfully bodge on a physical potentiometer, and can now adjust Vref for Y. With luck I’ll now be able to figure out if it’s overheating or a lack of current causing the layer shifts, or something mechanical that I’ve failed to spot.

Re EEPROM, I’ve disabled reading/writing settings to EEPROM in my build of Marlin, specifically to ensure I’m using the settings I’ve got in the code.

Glad to hear you’re happy with both the Duet & the Azteeg boards; I still have dreams of building something exotic for fun that would need the 32 bit horsepower- eg COREXYUV ;-) But I think my next experiment will be to try Klipper- generates all the step timings on a PC and sends these to the printer.

Julian

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[Edward Simpson]

Hi Julian,

The old spec of Ramps 1.4 only working on 12V is actually a limit imposed by the power regulator on the Mega2560 board, not anything to do with the Ramps shield. There's actually an old mod for using a Mega/Ramps stack with 24V power, you just need to remove the diode that diverts power to the Mega and give it an external supply, but that's not needed with the Re-ARM board :) 

I'm actually in the middle of building a custom Core-XY bot with my Duet as the brains, just sorting out some configuration quirks on it first.

Edward

[Julian Rendell]

Good to know re the micro power supply, but I didn’t read beyond the need to change the polyfuse for heated bed that also needs to be changed, ref https://reprap.org/wiki/RAMPS_24v

Maybe check the rating on your polyfuse- I just checked my spare ramps board and it definitely has the 16V rated polyfuse. But some more googling leads to this thread https://reprap.org/forum/read.php?219,433454 that suggests car fuses… which I should be able to get easily.

Hmmm… I think you’ve sold at least one Re-Arm :-)

Send me some pics when you’re finished with your machine- I know it’ll be interesting!

Thanks-

Julian

[John Grindon]

I have a couple of Duet 0.8.5 ethernet boards , NEW if your interested. Just give me a call 604-671-5875

John Grindon

Evolution 3D printer Inc.

[Julian Rendell]

Thanks John-

I'll email you directly... I'm bouncing around enough errands right now that phone calls are turning into too much phone tag :-(

Julian

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[John Grindon]

Are you still interested in a controler board ? I have not heard from you.

[Edward Simpson]

Hi John Grindon,

Do you still have one of the Duets on hand, mine's suffered a hardware failure of some sort that I can't figure out, so I'm interested if you have one for sale.

Edward Simpson

[Julian Rendell]

I got an email from Filastruder- they have a sale on Duets at the moment (if you can’t find something locally)

Julian

From: Edward Simpson <r2a...@gmail.com>
Reply: 3d...@googlegroups.com <3d...@googlegroups.com>
Date: June 11, 2019 at 11:09:18 PM
To: 3D604 <3d...@googlegroups.com>
Subject:  Re: Rambo problem -> Anyone selling 32 bit controller boards locally?

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