Chuck Fellows wrote:

> In the detailed engineering data measured during the door open block for TA #5 the value for the bus A current was observed to be roughly twice the expected value. Expected value was about 0.24 A and the actual value was 0.46A. The inlet and outlet vales were also pulling roughly 2x the expected values . The bypass valve and the EGA manifold heater drew the expected current. Preliminary indications are that we are powering two sets of valves(for both inlet and outlet) and two pin pullers .

> Looking at the High temp run just previously indicated the inlet valves for this system are functioning normally and pulling the proper current.

>

> Given these observations it is likely that a short has developed on the lower side of the inlet/outlet/pin puller mux on cell 4 causing it to activate when any of the other systems are activated. If this is true then from here on out we will be flowing gas through TA#4 during all future TA activities.

>

> This would be a minor violation of a S/C design rule on returning instrument current on the chassis

>

> Chuck

>

Dave hamara

I also checked the oven close actuator, and it is pulling twice what it should in the TA5 door open activity, but was operating normally at checkout 1.

I agree that the most likely culprit is a short from the low side of one of the TA4 actuators to chassis - the rerun of checkout 1 will give us the smoking gun.

Note that this will only affect the 5 TA actuators: Shaker, Door open, oven close, inlet valve, and outlet valve. Any activities using ovens, T-heaters, LEDs, or any of the other heaters / valves will not be impacted.

So of the planned sol 27 activities, only modified checkout 1 and the shake are in any way impacted by this problem, and those are intentional.