Electronics Issues

• Over the past 2 weeks the electronics have been not behaving as expected and most of the time have behaved erratically (sometimes working normal, sometimes not).
• On 2/17-2/19 it was determined that the master controller and the "dongle" cable are both fine. On 2/19 it was discovered that there was a blown resistor (R17???) near the Comm connector on the driver board. It measures "OPEN" instead of 100 Ohms. It is likely that this resistor was partially functional when the board was behaving oddly and that it finally failed when communication to the driver board could no longer be established.
• On 2/20 Charlie de-mated all of the Cobra flex prints from the driver board and removed the driver board from the module (while it was still in the Cold Box. He returned it to JPL for further investigation.
• In the coming days the spare driver board will be mounted to the module. Prior to any cable mates or power on, the following will need to be in place:
  1. The test stand needs to be grounded to the chamber or to facility ground
  2. The dongle needs to be re-built to connect the Master Board ground to the driver board ground (the cable already has the wires in place, it just isn't connected on the driver board side)
  3. Wrist straps, ESD mats and an air ionizer need to be acquired for any handling of electronics. The air ionizer MUST be used for any mates/de-mates. All people working around the test stand shall use wrist straps.
  4. Matt King needs to come up with a quick safe-to-mate procedure to verify everything is good to go before we mate the power/comm cables and then also before we power on.

-- ChazMorantz - 20 Feb 2015