Replicator MightyBoard Protection Part 2: ESD Shielding by garyacrowellsr

Last crawled date: 3 years, 1 month ago

From Part 1, we know that Replicator MightyBoards occasionally blow up. One of the suspected causes of those blow-ups is Electro-Static Discharge (ESD). Part 1 offered some protection from ESD on the EndStop data lines, and in this Thing, we'll try to improve on that to offer some protection to the Replicator in general.
The most common source of ESD damage is from the human body, discharging an accumulated charge into a sensitive electronic circuit. You accumulate a charge via motion or friction with an object. You discharge when touching a conductive object; i.e., that spark when you touch a doorknob. One of the insidious things about ESD damage in electronics is that it is cumulative. You might zap your Replicator, and it keeps on working, so you think you've dodged a bullet. But the damage may still be there, waiting to accumulate further damage with the next zap, or just planning to spontaneously distruct at some random time in the future. And here's another secret: ESD discharges that you may not even feel, may still damage your Replicator.
There are sort of three general ways to protect against ESD in a system:
Isolation; by preventing any path for ESD to reach sensitive circuitry.
Shunting; by providing an alternate path to ground for an ESD event by adding a device to the sensitive circuits.
Interception; by discharging the ESD source before it comes in contact with sensitive circuits.
... and I should also mention ESD prevention, see the beginning of the Instructions below.
Isolation is pretty much impossible in the Replicator. While you may think the wooden case would make this easier, the fact is that there are many sensitive circuits that are exposed throughout the box, that are easy for a user to come in contact with. Shunting was done with ESD diodes for the EndStop signal lines in Part 1, and more will be added to the LCD cable in an upcoming Thing. However, it's just not practically possible to get an ESD device onto every exposed line in the Replicator. (Note that the MightyBoard revision used in the Rep2 and 2X has ESD devices added to every line.)
That leaves interception, which this Thing is going to work on. It may or may not be attractive, depending upon your POV, but I think it will be a considerable help in keeping your Replicator safe from ESD damage. So, we're going to wrap a strip of conductive aluminum tape completely around your Replicator, and ground it. Plus ground the aluminum build plate (if you still use it) and the aluminum platform arms (if you have them). The idea being, that you will be likely to touch one of these items before you touch something sensitive in the Replicator. And, if you remember to consciously discharge yourself at one of these grounded points, even better.
Note that you may implement this Thing without having installed the EndStopESD board from Part 1. Note also that installation of this Thing is strongly recommended before installation of the LCD ESD add-on board that will be presented in Part 3.