Geeetech Mightyboard replacement for replicator 1?

[Andy Evans]

Hello, 

I have a Makerbot R1 I got with a fried board. I have been reading all the great info in this group for weeks now! :) I ended up getting a cheap Geeetech Mightyboard (http://www.geeetech.com/wiki/index.php/Mighty_Board), a new 24v power supply, cut the white wires on the end stop leads and am grounding the SD port.  Has anyone else used one of these boards? Also do I need to do the modifications that others(Jetguy?) have mentioned here to the voltage regulator? It is a bit different it has AC 1084 5.0 vs the LM1084 (same thing??). It also has the middle pin removed, which is odd, as I thought that was the 5v out. It does not have the trace cut to the 3.3v regulator and does not have the jumper from the 5v regulator. Not sure if I should add that also. It seems to also have a diode on the power switch under the board too, and AQV252g does not have the factory mod ether. I can send some more pictures or details for those interested. 

I will also try and update how this all works out for me. With any luck, I am going to try and use the DRV8825 drivers that came with it too. 

Thanks!

[Dan Newman]

On 14/02/2015 2:13 PM, Andy Evans wrote:
> Hello,
> I have a Makerbot R1 I got with a fried board. I have been reading all the
> great info in this group for weeks now! :) I ended up getting a cheap
> Geeetech Mightyboard (http://www.geeetech.com/wiki/index.php/Mighty_Board),

Return it if you can.

That board appears to be a literal implementation of MBI's published rev E
schematics -- the schematics for the board which MBI did NOT take to market.
Fortunately, no one making boards was clueless enough to take to market a
board exactly matching those schematics.... until now. For instance, that board has
the safetfy cutoff implemented: MBI never did that and indeed never tested
it. Hopefully, it won't give you any grief. (I don't know myself; I've only
examined pictures of Geetech board.) The Geetech board also has the microSD
slot installed. If you have issues with SD card reads, consider removing it.
(Me, I actually cut the traces running to the unpopulated pads for it since they
are unterminated, serve no purpose, and certainly pick up electical noise.
Actually populating that board position shouldn't make matters worse, but
may make it slightly easier for noise to be picked up -- think antenna.)

> And With any luck, I

> am going to try and use the DRV8825 drivers that came with it too.

You really don't want to use DRV8825 drivers. They work best for low step
rate applications.... For 3D printing they do not work as well as A4988's.
Everyone I know that has tried using them have found them to be unsatisfactory
(and noiser).

You would have been far better served paying an additional $65 - 70 for
a FlashForge rev E clone board. It would have come with all
the 5 and 3.3V improvements, the correct stepper drivers, auto-reset for
firmware uploads, and other known-good improvements.

Dan

[Andy Evans]

:( Yea, I can't return it. I guess at $100 with the drivers and LCD board it was to good to be true.  I had contacted flash forge with some questions, and never got a reply, so I opted for this one. 

Do you think I can swap the voltage regulator and do the other mods that MBI did from the factory and be able to use it ok? I am really confused about the middle pin not being used at all on it. 

I still have the A4988's from the fried board, I wonder if they are ok...   

[Dan Newman]

On 14/02/2015 2:50 PM, Andy Evans wrote:
> :( Yea, I can't return it. I guess at $100 with the drivers and LCD board
> it was to good to be true. I had contacted flash forge with some
> questions, and never got a reply, so I opted for this one.
> Do you think I can swap the voltage regulator and do the other mods that
> MBI did from the factory and be able to use it ok?

Do what MBI did? Possibly (depends upon your soldering skills). Be
okay? No, if all you do is what MBI did. After all, you have a blown
rev E board from MBI. They did mods. They weren't sufficient to keep
the board from blowing.

You need to read old posts on makerbot-operators and find the beneficial
mods which will help prevent the board from blowing. On the original rev E
boards I've modified, I used DC/DC converters and simply removed the 5V
linear regulator and used them instead. E.g., one of these,

http://www.digikey.com/product-search/en?pv573=68&pv573=34&FV=fff40042%2Cfff800df%2C401c68%2C402fde%2C1140050%2C114016f%2C15c0002%2C118000cb%2C1180015b%2C11800192%2C17d4003e&k=dc%2Fdc+converter&mnonly=0&newproducts=0&ColumnSort=0&page=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25

Mind you, their pinouts may be different -- you have to carefully read the spec
sheet and wire it correctly. I know of one EE who despite being careful
was still human and like the rest of us err'd. Blew his board as a result.

And cut the trace supplying 24V to the 3v3 regulator and feed it +5V on
its Vin leg.

> I am really confused
> about the middle pin not being used at all on it.

How many pins does it have? And note that the tab is an output and if
they are using the tab, then one of the pins is redundant.

> I still have the A4988's from the fried board, I wonder if they are ok...

Hard to say. If you are in the US and willing to re-imburse me $5
I can mail you a set of FlashForge botsteps. I have handfuls of them
since I replace them with Pololu A4988s so that I can drive 1.5A
stepper motors.

Dan

[Andy Evans]

I ordered one of these at the same time, incase it had the LM1084, http://www.digikey.com/product-detail/en/R-78E5.0-0.5/945-1648-5-ND/2834904. 

But the AC 1084 5.0 has the middle leg not attached to the board, it appears it is suppose to be snipped. So maybe the tab is supplying the 5v to the board? Could I follow directions to replace it like a regular MBI board?

That would be great! Can I just paypal you?

[Dan Newman]

On 14/02/2015 5:26 PM, Andy Evans wrote:
> I ordered one of these at the same time, incase it had the
> LM1084, http://www.digikey.com/product-detail/en/R-78E5.0-0.5/945-1648-5-ND/2834904.

Only 0.5A and also supplying the 3.3V regulator? I think that will be okay as I wouldn't
expect the 5V logic to need much more than 0.3A most of the time. I'm not too
sure how much more the 3v3 reg will draw. But a 1.0A part would have been a safer
bet.

> But the AC 1084 5.0 has the middle leg not attached to the board, it
> appears it is suppose to be snipped.

It can be snipped, but it's not required to be snipped. Since "snipping"
that leg takes effort, it probably an indication that the people fabricating
that board got a good deal on slightly defective parts -- parts that
had those legs damaged. Either that or they may not have understood what
they were doing.

> So maybe the tab is supplying the 5v
> to the board? Could I follow directions to replace it like a regular MBI
> board?

I don't know of any directions per se. Rather it's a matter of looking
at the data sheet for the existing linear regulator, the data sheet
for the dc/dc converter, and then matching the functional pins.

> That would be great! Can I just paypal you?

Yes. I'll send you the PayPal account in a private e-mail. I'll of course
need your US Postal Address.

Dan

[Andy Evans]

So I am looking at the mods mbi did at the factory and see they bridged pins 4 and 5 on the two AQV251A chips. Any ideas why they did this or the effect it would have? The geeetech one does not have them bridged...

[Ryan Carlyle]

The AQV25s are flip-flops used by the cutoff circuit to enable/disable the heater power output. The pads were bridged to disable/bypass the cutoff circuit. No one really knows if the cutoff circuit would have worked -- it's obviously a bad design, but having no protection circuit is an even worse design. The code to support it is crazy unsupported though, so good luck getting it working.

[Ryan Carlyle]

Sorry, mis-spoke, they're solid-state relays that are driven by the flip-flop.

[Andy Evans]

Ok makes more sense now. Looks like I should just disable it, but it is disabled in the software, so I don't have too. More info, including the schematic here: https://groups.google.com/forum/m/#!topic/makerbot/TIjz68diHn4
Thanks!

[Ryan Carlyle]

Are you sure it'll output power with the software disabled?

Note, all the "new" RevE boards do not place any of the cutoff chips and include jumpers in the PCB itself, not solder blobs.

[Ryan Carlyle]

By the way, full schematic: https://www.thingiverse.com/thing:16058

[Andy Evans]

Great news everyone!

Everything worked out great. I did the factory mods, replaced the voltage regulator, upgraded the PSU, cut the white wires(5v) on the end stops, used the FlashForge botsteps from dnewman(double thanks!) and everything is working fine. Thanks everyone for your help and feed back!!

[Ryan Carlyle]

Nice!

[tjp...@gmail.com]

Considering the length of that list of mods, I salute you! Great work. Glad it is up and running for you!

[TobyCWood]

Dan... what do you think the FF replacement board rev is???

http://www.flashforge-usa.com/shop/parts-accessories/mightyboard.html

[adam paul]

I'm pretty sure it's a rev e with 2560 mega

[Dan Newman]

On 15/04/2015 10:24 PM, TobyCWood wrote:
> Dan... what do you think the FF replacement board rev is???
>
> http://www.flashforge-usa.com/shop/parts-accessories/mightyboard.html

It's a rev E with fixed 5V voltage regulator. They come with the RGB LED
circuitry + connector, the Extra FET + terminals, and an ATmega 2560. I've
used probably 10 or so of those boards. However, I pull all the "euro" style
terminals and install properly rated screw down terminals with the exception
of the power. For the power, I just solder down 16 awg wire. I have to
enlarge the PCB holes a tad for that. 18 awg is fine as well (16A); 16 awg is
overkill (22A)

Dan

[Joe Soap]

I've lost the stepper drive for my left nozzle, so it is possible that my 2X might need a new MightyBoard, and this GeeeTech board looks a possible candidate. However my MightyBoard is rev H and the GeeeTech version is rev E. That means that the connections to the MightyBoard would need modifying.

I could remake the connections by replacing plugs on the leads. However I'm wondering whether creating short tails to do the connector changeover might be a possible option? That might sound like a lot of extra work, however I would value thoughts on this.

[tramalot]

2x is not the mightyboard e? clone board, post a pic, i think they are ~200 or so compared to 140ish, one reason we all hate mbi

[Ryan Carlyle]

I would avoid the Geeetech board like the plague, it requires modification right out of the box. You can do a FlashForge or Wanhao Mightyboard RevE conversion much, much easier -- they already have the minimum mods to function properly. But there are no drop-in replacements for a R2x RevH except a genuine Makerbot RevH. You have to change the LCD or modify the LCD wiring as well as changing all the connectors and wiring.

But I doubt you need a new Mightyboard if the stepper has stopped running. Try swapping wiring or BotSteps to see if the problem moves. 

[Dan Newman]

On 04/05/2015 11:10 PM, Joe Soap wrote:
> I've lost the stepper drive for my left nozzle, so it is possible that my
> 2X might need a new MightyBoard,

Why not just replace the small stepper driver "botstep" card? There's
five of them and you can just swap the left and right nozzle ones to see
if the left one has indeed failed. If it has, then just buy a couple of
new botstep cards: one to use and one for a spare.

and this GeeeTech board looks a possible
> candidate. However my MightyBoard is rev H and the GeeeTech version is rev
> E. That means that the connections to the MightyBoard would need modifying.

Including fixing the 26 pin ribbon cable to not send the 3.3V from the rev E
board to ground on the LCD/SD/keypad board thus damaging/destroying your clone
rev E board. You may want to search for past posts on this subject: the
LCD/SD/keypads are not compatible between the rev E and G/H boards and you
need to modify the 26 pin ribbon cable to prevent damage to a rev E board.

Dan

[Andy Evans]

I am with the others here, it sounds like your botstep card. I also having modified and used/using a geeetech I would not really recommend them unless you are on a very tight budget. Mine did come with an extra display board though, as most do for the cheap price, so if you did go that way, you could always "downgrade" to the older style one that comes with it. I also have an extra one I am not using you could have if you went that way and it did not come with a screen. 

--

-Andy Evans

[Andy McClary]

I’m in the same situation as Andy Evans with replacing a Makerbot Mightyboard with a Geeetech Mightyboard by no fault of my own due to a bad description from a ebay seller. I was wondering if you have any suggestions on how to fix a geetech board (rev E). I already added a switching regulator to drop the 24V down to 5V and patched it into the 3.3V regulator. I'm not sure on what is going on with the safety cutoff circuit (AQV252g) or the micro SD card slot. I’m also not quite sure what to do with the stepper motor drivers (DRV8825), if I should replace them and if so with what.

[Ryan Carlyle]

Err, wait, 8825s? Really?  Can you take a good photo of the board? If not, can you at least say whether the driver daughter boards have all the parts (resistors, little trimmer potentiometer) on the top facing you, or facing down to the board with a heatsink on top? (Look like this or oriented the other way: http://www.geeetech.com/stepstick-drv8825-stepper-motor-driver-carrier-reprap-4layer-pcb-p-652.html)

[Ryan Carlyle]

To be clear, Mightyboards require the drivers to be installed "upside down" relative to RepRap boards. (The Mightyboard way is actually better for heat dissipation, the RAMPS style drivers are not designed well and cannot handle as much current for the same ambient temp/cooling.) I'm not aware of anyone making DRV8825 boards in the correct orientation for Mightyboards. 

I'm also not aware of anyone making 8825 boards that accept an external Vref to suit the Mightyboard's gcode-adjustable driver current control scheme. That's not a huge loss, but you have to be aware to keep the Vref pin disconnected so you don't send a spurious voltage signal to the wrong pin on the driver board. 

All this to say, I'm concerned that Geeetech popped some random RepRap style drivers into the board, and it's going to do Bad Things (TM) if you power it up with them wired that way. 

[Ryan Carlyle]

In terms of performance, 8825s will probably work ok if wired correctly. I haven't tried them with the specific Moon's 17HD-4063-xxN steppers used in Makerbots and clones. But 8825s have a tendency to make annoying hissing noises and put little ripples into the print at very low speeds, so I don't recommend them for this application. 

[Andy McClary]

The boards have the pots facing down with a heat sink on the top. My main problem with them is I can't adjust them because the pot is on the bottom. If I do replace them, are the ones from flashforge a direct drop in for the bot steps.
Here are the photos you requested.
https://goo.gl/photos/kyXX4ZhM873vZc3v6
Thank you.

[Andy McClary]

As a side note when I do power them on they are really loud and hiss a lot (compared to my thing -o- matic ). My main concern is after a couple of minutes of joging they get really hot.

[Ryan Carlyle]

Ok, at least it's not upside down. At a glance, I think the microstepping jumpers are configured wrong. Would take some digging to sort that out, I don't have time at the moment, maybe Jetguy or someone else can chime in. 

Hot may be fine, it's really supposed to be too hot to touch. Or it might mean the current is set too high. You'll know if the drivers are overheating because the thermal protection will turn the drivers off intermittently. This will show up as skipped position steps during prints. 

Hissing is fairly common with 8825s. It depends on the motor and PSU you're using though. 

Yes, setting the current on a Pololu-style driver mounted on a Mightyboard is a pain. You can look up the math to use a multimeter to measure the trim pot voltage divider resistances and calculate the right setting, or you can do it by "feel" (preferably an IR thermometer gun) from how hot the stepper motors get. They should get hot but not "burn you" hot after extended running. 50-70C is good. Pay particular attention to the Z stepper, I don't recall the exact one used for your printer but they're often rated to rather low currents compared to XYAB steppers. 

[Andy McClary]

Thank you.
Given the information you provided to me it looks like my best rout is to replace them with a better stepper driver. My main consern is I can't tune them and even if I do manage tune them to for my motors they are still going to be inferior. I saw that Andy Evans replaced them with the stepper drivers from flashforge, but do those require tuning a pot or do they have the VREF pin input ?

[Ryan Carlyle]

Drivers from FlashForge, Wanhao, or MBot should be compatible and accept the proper Vref from the mainboard. 

That's assuming, of course, Geeetech didn't do something silly to the mainboard design. 

[Andy McClary]

Thanks for the info.
Between the three of them which would you suggest.

[Ryan Carlyle]

Whichever is cheaper between FlashForge and Wanhao. 

[Andy Evans]

Sorry for the delay, I think all your questions have been covered. As far as the cutoff, you just need to add solder to the legs of the 2 ICs just like the makerbot one would have had. Also don't forget to scratch/cut the power trace to the 3.3v regulator.

The flashforge stepper controllers work very well and are fully compatible.

Good luck!

--

-Andy Evans

[Andy McClary]

Thank you very much.
If you don't mind can you post a picture of what two pins to short out on the AQV251A chip look like. I don't have a makerbot mightyboard to reference.

[Andy Evans]

I don't have access to mine at the moment, but you can see it in this picture.

http://www.akeric.com/blog/wp-content/uploads/2015/01/board_before.jpg

On Mon, Jul 13, 2015 at 3:12 PM, Andy McClary <andyam...@gmail.com> wrote:

Thank you very much.
If you don't mind can you post a picture of what two pins to short out on the AQV251A chip look like. I don't have a makerbot mightyboard to reference.

--

-Andy Evans