Replicator MightyBoard Protection Part 1
by garyacrowellsr, published
Description
Replicator MightyBoard Protection Part 1: ENDSTOP
Replicator MightyBoards blow up. We know this because there have been at least a couple of dozen such reports on the Makerbot groups. There are certainly many more that we don't hear about, that are handled directly through Makerbot support. To date, Makerbot has handled board replacements very well, but given a choice, it would be better to avoid these blow-ups if possible.
By 'blow up', we mean that the 5V regulator on the MightyBoard really does explode, with a 'pop', smoke, and smell that's a pretty distinct indication that Something Bad has happened. There are several suspected causes for this problem, but one that is fairly certain is an instance of a short occurring in an endstop cable, resulting in a 'popped' regulator (see photos). This Thing prevents that type of short from destroying the board, and possibly avoids some other problems too.
This Thing is a small circuit board that plugs into the endstop connectors on the MightyBoard. The three endstop cables are then plugged into this board. The board does the following:
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A 1k resistor is added in series with the 5V that is supplied to each endstop cable. A short can still occur in the cable, but without the 'hard' 5V, all it will do is cause the endstop function to fail. Otherwise, the endstops will function normally, but the LED's may be dimmer.
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The MightyBoard 5V linear regulator is replaced with a switching regulator module. When the existing 5V regulator fails, it apparently applies 24V to the 5V rail, which destroys most of the components on the board, making it unfeasible to repair. Hopefully if a short occurs on the board, this switching regulator will shutdown gracefully, without propagating damage elsewhere. And, as a bonus, this reduces the power consumption, and waste heat generation, by about 3 Watts.
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ESD prevention diodes are added to the microcontroller endstop inputs. These might aid in preventing ESD damage to the Replicator, but it's difficult to judge how effective they may be.
- When this was started, it wasn't anticipated that the three unused endstop inputs to the MightyBoard would ever be used for anything, but that may change. Due to space limitations I didn't bring them out on the original EndStopESD board. However on this newer board I did bring these three endstop lines, plus a ground, out to a single 4-pin connector. It will take some creative placement, but a right-angle connector can be added there. It will have to 'stack' on top of some other components. 10K pull-up's have been added to each of these signal lines, so a simple switch closure to ground will toggle an input to the processor.
Caveat: This thing won't make your Replicator print faster, or make your prints look better. It's simply insurance against a small subset of the Bad Things that could happen to your MightyBoard. Worse, it involves some minor modification to the MightyBoard, which could void any warranty replacement of the board by MBI. However you should consider that in the not too distant future, your Replicator will become an unsupported 'legacy product', and replacement of your MightyBoard may become a complicated and expensive proposition. Up to you.
Also note that this Thing won't 'repair' a board that has already failed. You might consider adding it when installing your new board though.
This Thing is Part 1. In some following Things, I hope to patch a few more holes.
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I'm sorry for your loss. Fortunately there are several aftermarket companies that make aftermarket controller boards for the Replicator, and the cost is not unreasonable (on the order of $150), and as a bonus most of them have fixed the flaws that usually kill a MightyBoard. I haven't had to deal with a replacement myself, but I understand that this is one of the better ones: http://www.flashforge-usa.com/shop/parts-accessories/mightyboard.html
As an added bonus, this one gives you a 2560 processor instead of the original 1280, giving more memory which allows new functions if you use the Sailfish firmware. The replacement is not terribly difficult at all, and is mostly just a wire-for-wire swap. There are lots of folks that will help you on the FlashForge Google Group. Those Rep 1's will last a long time, and with care and a few upgrades can print as well as any new printer on the marker (and better than some). Hmm, I see it's $185; more than I thought. I also don't know about the SD/Display board - it may need replacement and I don't know about the cost or source for that one. The Google Group will help though.
If your board suffered a typical regulator blow-up, this is usually easily identified by physical damage to the large regulator chip that is near the switch and power connector. I would really appreciate it if you could take a look there and confirm that and let me know.
Ahhh! I just fried my Replicator 1.
Don't know why there was so much static build up on this particular day. Warm weather, air conditioning, weird rubber type carpet. But these have always been the conditions I have worked with. I noticed electric static while touching the LCD button which made the LCD screen display strange characters. Apparently I had turned my Replicator into a Ouija board. I immediately restarted the machine and took ESD precautions, touching metal right before touching it again, but when I went to take out the SD card, huge static shock and the whole thing went dead and emitted an odor of burnt circuitry.
I am tempted to open it up and see if I can replace any bad circuit boards, but am afraid I will just waste lots of time. I suppose I could pick up an old broken Replicator one and salvage parts?
Anyway, definitely a bad design.
I have worked with this Replicator 1 for two years and had no problems.
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Instructions
Even without this board, it would be a good idea to practice good ESD (Electro-Static Discharge) prevention around your Replicator at all times:
- Avoid wearing clothing that generates static electricity.
- Avoid placing your Replicator in a carpeted area.
- When approaching your Replicator, touch something grounded before you touch the Replicator.
- Be aware that low humidity conditions can increase ESD problems by a factor of 10X.
Note also, that the ESD prevention function of this board is useless if the Replicator is not plugged into a grounded outlet. (Some 3-prong outlets, especially in older homes, may not be grounded.)
Materials:
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You need an assembled EndStopESD board, or if you're building yourself, a bare board and the components listed in the bill-of-materials. With the included Gerber files, an order from OSHPark.com will get you three blank boards for about $7.50.
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(1) M3-15mm screw and nut to act as a central ground stud on the back of the Replicator. (Or M4.) The screw length is uncritical, and it would be best to have two nuts, one of them a jam nut if possible.
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(2) Small ring or spade crimp lugs.
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About 4" of wire, 16-24 gage.
- About 8" of 4-to-8 conductor ribbon cable, for the ESD ground connection. Ordinary 16-24 gage wire may be substituted if ribbon cable is not available. I prefer ribbon cable, as it's flexible, and multiple conductors will offer a lower impedance path to ground than a single larger wire.
Tools:
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If building from scratch, you will need a small soldering iron, fine wire solder, flux, and other normal soldering tools. A magnifier will probably help. The surface mount assembly on this board is actually not that difficult - it would be a good first SMT board if you've never worked with surface mount before. (Oven or skillet reflow would be fine too, if you know that.)
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A large soldering iron or gun, sufficient to make the connection to the top of the power connector.
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Allen wrench to access the MightyBoard area.
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Small side cutters.
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Wire strippers.
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Drill and bit appropriate for a 3mm (or 4mm) screw.
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Crimp tool.
- It wouldn't be a bad idea to wear an anti-static wrist band when working around your Replicator. (Note that so-called “wireless†or “cordless†anti-static wrist bands are a hoax, and are less than worthless for preventing ESD damage.) To be effective, the wrist band must be grounded.
Skills:
You will need to be able to solder a wire to the power switch, and solder a ground wire to the top of the power connector. You must be able to identify and cut the legs of the existing regulator. If building from scratch, you must have the soldering ability to assemble the board.
Printing:
There is nothing to print for this thing per se, however to expedite assembly I did print a block to hold the connectors in place for soldering. The connectors must be held vertically and well aligned in order to get all six of them to mate with the MightyBoard connectors. If you're going to try assembling one of these yourself, this helps. (To be included with this item on Thingiverse later after I rework it for the latest boards.)
Installation:
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Remove the power and USB cables and orient your Replicator on end. Remove the bottom plate to expose the MightyBoard.
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If you haven't done so already, this is a good time to install the Replicator Power Cord Support Bracket by DDStarkey. This will prevent damage to the MightyBoard power connector, and will absolutely prevent incorrect insertion.
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Drill a hole in the Replicator back panel for a ground screw. Right about through the 'n' in Brooklyn is a good spot. Be careful to not damage any wires inside. Insert a screw and nut and tighten.
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Prepare a 2.5 inch piece of 4-8 conductor ribbon cable. On each end, individually strip the ribbon cable wires and twist the wires together. On one end, crimp a ring lug. Do not presolder the wires in the crimp. If it's a good crimp you don't have to solder at all; but you can afterwards if you must.
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Solder the other end of the cable to the top of power connector shell. This will require time and the heat of a large soldering iron or gun. Don't leave any loose strands of wire unsoldered. Place the ring on the other end over the ground screw.
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Prepare a 3 inch solid wire. Strip both ends. Solder one end to the '+24V' point on the EndStopESD board.
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Prepare a 4 inch ribbon cable, as before. Solder the bare end of the wire to one of the 'ESD GND' points on the EndStopESD board.
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Label and remove the endstop cables from the MightyBoard.
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Find the chip labeled U13 on the MightyBoard. It has a green modification wire connected to the center of three pins on one side. Using you small side cutters, clip the outer two pins so that they are completely disconnected from the chip. Leave the center pin and its wire in place.
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Insert the EndStopESD board onto the MightyBoard by plugging the six connectors on the bottom into the six endstop connectors of the MightyBoard. Orient the board so that the end with the 'ESD GND' pads is closest to the power connector. Ensure that the connectors are mated fully.
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Solder the wire from the 24V pad on the EndStopESD board to the pin on the power switch that is closest to the power connector.
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Place the ring lug from the EndStopESD ESD GND wire over the ground screw on the rear panel of the Replicator. Add a nut (preferably a jam nut) and tighten so that the ground wires from the board and power connector are captured. The two ground cables should be routed as far away from the MightyBoard as possible and as much as possible, should not run parallel to, or be bundled with, any other wires.
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Plug the endstop cables into the EndStopESD board. The connector labels on the board may be difficult to see; from the ESD GND holes they are, in order: X-MAX, Y-MAX, and Z-MIN.
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Check your installation:
- Did you clip both legs on U13, leaving the center leg and its wire intact?
- 24V wire connected to the correct switch pin?
- Ground wires connected?
- Endstop cables installed in the correct positions?
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With the Replicator still on its side, plug in the power connector and turn the power on. The green led at the end of the EndStopESD board should glow, and the Replicator should power up normally.
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Turn the power off, replace the Replicator bottom plate, and set it upright.
- Power up the Replicator and from the front panel menu, jog into each endstop. If the carriage or platform doesn't stop at an endstop, an endstop cable is probably inserted in the wrong position.
The installation is finished. Your MightyBoard should have a bit less chance of having a catastrophic failure and your Replicator should function completely normally.
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This addition is great.
My replicator mightyboard blew up from a static discharge as well :(
I ended up switching to a flashforge mightyboard. It is better designed, and it has a better processor in it allowing the use of sailfish.
I highly recommend the replacement http://www.flashforge-usa.com/shop/parts-accessories/mightyboard.html
One note though, most of the connectors on the flashforge board are different, requiring you to re-terminate everything. It isn't a process for the non-advanced user.
Ahhh! I just fried my Replicator 1.
Don't know why there was so much static build up on this particular day. Warm weather, air conditioning, weird rubber type carpet. But these have always been the conditions I have worked with. I noticed electric static while touching the LCD button which made the LCD screen display strange characters. Apparently I had turned my Replicator into a Ouija board. I immediately restarted the machine and took ESD precautions, touching metal right before touching it again, but when I went to take out the SD card, huge static shock and the whole thing went dead and emitted an odor of burnt circuitry.
I am tempted to open it up and see if I can replace any bad circuit boards, but am afraid I will just waste lots of time. I suppose I could pick up an old broken Replicator one and salvage parts?
Anyway, definitely a bad design.
I have worked with this Replicator 1 for two years and had no problems.
I'm sorry for your loss. Fortunately there are several aftermarket companies that make aftermarket controller boards for the Replicator, and the cost is not unreasonable (on the order of $150), and as a bonus most of them have fixed the flaws that usually kill a MightyBoard. I haven't had to deal with a replacement myself, but I understand that this is one of the better ones: http://www.flashforge-usa.com/shop/parts-accessories/mightyboard.html
As an added bonus, this one gives you a 2560 processor instead of the original 1280, giving more memory which allows new functions if you use the Sailfish firmware. The replacement is not terribly difficult at all, and is mostly just a wire-for-wire swap. There are lots of folks that will help you on the FlashForge Google Group. Those Rep 1's will last a long time, and with care and a few upgrades can print as well as any new printer on the marker (and better than some). Hmm, I see it's $185; more than I thought. I also don't know about the SD/Display board - it may need replacement and I don't know about the cost or source for that one. The Google Group will help though.
If your board suffered a typical regulator blow-up, this is usually easily identified by physical damage to the large regulator chip that is near the switch and power connector. I would really appreciate it if you could take a look there and confirm that and let me know.
Added an 'Assembly Notes' .pdf for anyone who wants to build one themselves.
Parts and boards have arrived, but I'm going to be gone next week. I should have assembled boards about two weeks from now. I still have to sit down and figure out what these are going to cost.
Hi, so what about boards ordering? I have no chance to make it by myself, so just tell us about its price :)
+1 Are these for order? Or sold out and we need to make them ourselves?
Hi - great work! I think I spotted a small error in ENDSTOPESDSCH.pdf: C2 is labeled as a 10uF capacitor but in the BOF it is 47 uF. I guess the BOF is the correct one?
You are correct sir! In the schematic, C2 should be 47uF, 10V. Not terribly critical value, but I will get that fixed.
Thanks
I have parts and boards on order for a small quantity build. Probably will be 3 weeks before they are assembled and tested. I'll announce here and on the forums when they are ready, and I'll give you a shout. Note also that there will be a companion board for the LCD cable presented in Part 3, and I strongly recommend that the two be installed as a pair.
Write please on [email protected] or here when the boards will be available for sale. I`m really interested in this :) because i have already two dead mightyboards at home.
Heh, I just noticed that the picture above was taken during testing, before I realized that the ESD diode chip was installed upside-down. That produced some really interesting symptoms. I never was able to perceive the slightly sloped edge that is supposed to denote polarity on that chip. The best I can say is that the "ST" logo is at pin 1. I'll be adding a document that details that and some other component polarity notes.
It's been interesting following the discussions on the Maberbot Users mailing list, and it's great to see this come together.
Awesome thanks for doing this. I've ordered all the parts and hopefully this will offer me a little more protection.
Full instructions are available as a .pdf in the downloads. I have boards on order for a small quantity build of these boards. I will announce here and on the MakerBot fourm when they are available. There is a companion board to this board, that plugs into the LCD cable, offering further protection. That board will be presented in an upcoming Thing.
This addition is great.
My replicator mightyboard blew up from a static discharge as well :(
I ended up switching to a flashforge mightyboard. It is better designed, and it has a better processor in it allowing the use of sailfish.
I highly recommend the replacement http://www.flashforge-usa.com/shop/parts-accessories/mightyboard.html
One note though, most of the connectors on the flashforge board are different, requiring you to re-terminate everything. It isn't a process for the non-advanced user.