Mightyboard Ventilation Upgrade prevents burnout due to weak stock voltage regulator, how to rewire?

[Elbot]

I am doing the mightyboard ventilation upgrade to prevent another mightyboard voltage regulator burnout. It is upgrade 24066 by Dave Randolph. Anyways, I want to do the cable pass thru support with fan mount and I've already printed it out in ABS plastic but I'm not sure how to unattach and reattach the braided red/yellow/green/gray wires. All the wires seem to be attached to the last stepper driver closest to the z axis motor. Do I just rip out this small green stepper driver board and plug it back in later? Or is the stepper driver soldered in and I will damage the mightyboard if I do this?

Or, do I just yank out each wire individually from the stepper driver board and then plug them back in later? Or, are these wires soldered in and doing so will damage the board?

Or, just cut all the wires, drop in the upgrade, and resolder the wires together. I hesitate to do this because my soldering skills are crappy. I just braid wires together and melt a big ball of solder over everything then wrap in duct tape. (not good!!!) Please advise. Thank you.

P.S. In case you're wondering, My mightyboard burned out due to the voltage regulator burning out. So, to prevent my 2nd board from burning out, I am taking a 2 pronged approach;
1. using a true sine wave battery UPS with a very big and heavy industrial voltage regulator to make sure my power is clean and free of voltage spikes.
2. doing these upgrades from thingiverse; 24066, 29858, 37387, 29493.

[Jetguy]

"P.S. In case you're wondering, My mightyboard burned out due to the
voltage
regulator burning out. So, to prevent my 2nd board from burning out, I
am
taking a 2 pronged approach;
1. using a true sine wave battery UPS with a very big and heavy
industrial
voltage regulator to make sure my power is clean and free of voltage
spikes. "

Those have nothing to do with the problem, nor does the extra cooling.
The primary problems I have identified with the system revolves around
the fact the regulator is being fed on the high end of it's voltage
range (in other words, fed 24V and expected to regulate it down to 5
volts. We see 2 types of main failures and a smattering of others. The
first is the firmware update or shortly after, and the second main one
is static. There is also a chain of filaures when the endstop cable
shorts internally. I consider the first 2 spontaineous while the cable
issue is just that, something much more direct and easy to target.

head my advise, cooling has nothing to do with this. Your failed board
and not a single one I have seen ever (inlcuding the box of failed
boards people have now sent me) not one has heat witness marks on the
board indicating the failure was heat related in a way that a fan is
going to fix.
Nothing wrong with changing the fan to something more quiet, but don't
fool yourself into thinking that in any way fixes the problem.

The point is, there are 4 main fixes that should prevent the blowout
Step1, put a 7812 12 volt regualtor in series to feed the onboard 5
volt regulator from the 24 volts. It needs a good heatsink but is
perfectly capable of doing the job.
Step2, remove the white 5 volt wire at the motherboard from all the
endstop cables as it's not needed for operation.
Step3, remove the 5 volt pins on all the botsteps so that they cannot
ever backfeed 24 volt motor power into the 5 volt bus. The diode will
of course provide a 0.7 volt drop thus feeding the botsteps with ~4.3
volts, but they are rated to operate below 4 volts and thus a complete
non- issue on the logic side.
Step4, put a reverse protection diode across the power connector input
on the mightyboard. Needs to be a beefy, fast diode that could hand
the surge of the power supply dumping it's caps reverse voltaged but
is there to trip the crowbar and attempt to prevent as much current as
possible from hitting the board.

Again, nothing wrong with upgrading the fan, but the above notes are
the real fix.

[Jetguy]

Sorry for the typos and I'll put another mod up on thingiverse with
instructions to do the above.
It requires soldering and cutting traces on the mightyboard. The
problem is the design, and nothing external is going to be the quick
or easy fix.
The first stages of the mod are easy. Step3 rquires skill to desolder
the pins and replace them with diodes.
The good news is, the parts are at Radioshack or just about any common
electronics and should be easy to get worldwide.

Trust me, I've put weeks worth of effort and testing and looking at
dead baord to identify the best aproach at prevention.

Also, just know that it's nearly impossible without a serious SMT
rework station to fix a board that had the regulator blow. It takes
out most every chip on the board, not just the easy to replace mega
1280, and that's not childs play. The 8u2 would make experienced folks
with rework reconsider the task.

> > 2. doing these upgrades from thingiverse; 24066, 29858, 37387, 29493.- Hide quoted text -
>
> - Show quoted text -

[Clinton Hoines]

Jetguy, I seem to remember you having a "how to" of sorts for all the mods listed in your post. Can you link that here? I'd like to do this on the weekend see if I can prevent having to replace the board any time soon. And thanks for taking the time to explain and show how this is done BTW. :)

 

Clinton

[Joseph Chiu]

 +1 this list.  Heck, for the protection diodes, you can easily source .3 V Schottky's to withstand 30V in reverse, if the "standard" 0.7V seems too much.

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[Jetguy]

Like I said, I pulled the data sheet and did some serious analysis
before even doing the mod, let alone posting it.
What is came down to is diode physical size. In order to not have
wires and another shennannigans all over, I needed a diode that fit
into the space the black spacer on the headers on the botsteps took up
for a stock look. Once you see the pics, it will make a lot more
sense. I basically desolder the pin, cut the header spacer, and then
solder a diode in place of the pin. Then plug the Botstep in like
normal.

Further, the current is so small it's not even worth figuring out. The
5 volt is only for logic and there's not enough to matter.

ELECTRICAL CHARACTERISTICS1 at TA = 25°C, VBB = 35 V (unless otherwise
noted)
Logic Supply Voltage Range VDD
Operating 3.0-5.5 V
Logic Supply Current IDD PWM
< 50 kHz 8mA

Outputs off 5mA

Sleep Mode 10μA

Basically, they don't draw enough to barely light an LED.

> > For more options, visithttps://groups.google.com/groups/opt_out.- Hide quoted text -

[Jetguy]

Some of the info is in the Mightyboard Failure analysis thread. While
it jumps around, I find even reading what I wrote myself interesting.
http://groups.google.com/group/makerbot/browse_thread/thread/e67e07c16c9ace51/9be2903b7e4ae54f?lnk=gst&q=mightyboard+failure#9be2903b7e4ae54f

I more or less nailed it on the first post. It's not that the voltage
regulator is weak in the current department, but really more of a
design issue where running a device in the upper portion of the
ratings isn't ever good for production. Being I started my engineering
degree just before I had my first Cupcake printer and finsihed it last
January, quite and adventure in studying what not to do when looking
at MakerBot electronics.

And, of course, despite what Bre said elsewhere, Mightyboard 2 in
Replicator2 and the 2X is a serious change from the orginal design on
many levels. The entire circuit has been changed. And, based on the
only picture I have seen of the MIghtyboard 2, they implemented many
of the proposed fixes in some form or another and thus why you don't
hear horror stories of them blowing out. Just a guess but it looked
like either they put individual regulators for each botstep (kinda
backs up on theory they cause the blowup), and not entirely different
from Gen4 where each stepper driver had it's own regulator. I don't
know for sure though, they won't release the schematics. All I have is
one bad picture and I'm not spending $2,200 or $2,800 to find out.

[Elbot]

”The first is the firmware update or shortly after”
So, does that mean i shouln't update to sailfish firmware if your proposed upgrade is beyond my soldering ability? Does the faster sailfish print speed make the roblem worse?

Also, i still dunno how to detah n reattach those wires help. Thanks.

[Dan Newman]

On 5 Feb 2013 , at 2:19 PM, Elbot wrote:

> ”The first is the firmware update or shortly after”
> So, does that mean i shouln't update to sailfish firmware if your proposed upgrade is beyond my soldering ability? Does the faster sailfish print speed make the roblem worse?

The point was that some of the board failures have been associated with upgrading the firmware.
Those incidents had nothing to do with what the firmware was -- just that the uProcessor was put
into the mode in which it rewrites its flash memory and uses several of it's pins for an alternate
purpose at that time.

Dan

[Jetguy]

Sorry, but your question really makes me think you are in over your
head. If you don't know how to remove the wires (they are either screw
terminals on the green ones, or the black ones are mostly friction
lock with the exception the endstop and LED have locking tabs), then
you certainly should cut traces or a solder anything. Not trying to
knock your skill level, but jsut make an honest assessment.

I would ask if there is any local Operators near you to try and help.

[HelpingHands]

Missing from Jetguy's response is the word "not," meant to be inserted between "then
you certainly should" and "cut traces or a solder anything."
What I mean to say is, the proper meaning of his message is DO NOT CUT OR SOLDER ON YOUR BOARD.
Sorry Jetguy, my internal grammar and spelling nazi had to make sure this was addressed for clarity.

[Elbot]

No, i wasn't referring to jetguy's complicated upgrade. I was only referring to my original question regarding dave's airflow rework upgrade, ”I'm not sure how to unattach and reattach the braided red/yellow/green/gray wires. All the wires seem to be attached to the last stepper driver closest to the z axis motor. Do I just rip out this small green stepper driver board and plug it back in later? Or is the stepper driver soldered in and I will damage the mightyboard if I do this?

Or, do I just yank out each wire individually from the stepper driver board and then plug them back in later? Or, are these wires soldered in and doing so will damage the board?”

Thanks.

[Jetguy]

"Or, do I just yank out each wire individually from the stepper driver
board and then plug them back in later? Or, are these wires soldered
in and doing so will damage the board?”

No, the wires are all in connectors, Just pull on the wires together
and the entire thing slides off the pins intact. Further, the Botsteps
are also in sockets and just unplug. Your hesitation worries me in
that you didn't know that was a connector and how to remove it.
See, this statement really worries me , "All the wires seem to be

attached to the last stepper driver closest to the z axis motor"

The answer is no wires attach to any of the botsteps. They do attach
to either green screw terminals or slide on rows of pins on the main
board that the botsteps plug into.

Are you in the process of changing the blown board to the new board?

Anybody got instructions from MakerBot with some pictures of changing
a Mightyboard?

[Elbot]

Yeah, mbi sent board w no instructions.

[Jetguy]

Sorry, here are some instructions but searching for the good ones
https://groups.google.com/group/makerbot/browse_thread/thread/dd01912e9f1befa9/3e2bd101ff235f4a?hl=en&lnk=gst&q=mightyboard+instructions#3e2bd101ff235f4a

[Gary Crowell]

On the Rep2 motherboard there doesn't seem to be any added protection with respect to the BotStep 5V power.  All seem to be connected to the general board 5V.  Unless they changed the BotSteps - haven't looked at those.  They did, of course, move the BotStep locations, so they're distributed over the board instead of clustered - that might have helped cooling.

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[Jetguy]

Thanks for that. I would love it if a Rep-2 owner posted or sent me
some pictures of the board. I hate flying blind on that system.

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