As I was crawling into bed......... 

I noticed that the temperature of the regenerating GN2 flow leaving the heater was 68C -> it should have been much higher.  After 5 minutes, I refreshed the screen and it was then 55C -> I realized that the heating of the regeneration flow had stopped, sent Chandra R. and Gerardo M. a text and set off to the Y-mid.  Upon arrival, I noted that the dewar vapor pressure was as expected (18 psig) and the flow of rengenerating GN2 was also as expected at 50 SCFH.  In the VEA, I noted that the temperature of the GN2 leaving the heater was now 16C? 18C?  Next, I noticed that one of the RED indicator lamps on the Regeneration Control Panel was illuminated -> I reset this before noting which of the two lamps was lit (they are side-by-side).  Upon reseting, the GN2 temperature began to rise too quickly as the sepoint was 150C and the proportional gain was 7.  -> I lowered the SETPOINT to a value slightly above the current value and also lowered the proportional gain value but the PID was too slow and the GN2 temperature continued to rise too quickly.  Next, I turned off the heating at the control panel (small switch - not main Panel Power) and let the temperature stabilize.  Once stable, I set the proportional gain to 1.00 and the SETPOINT value to 2C above the currently displayed value.  Then, I turned on the Regeneration Heater.  Now the "SHORTED SCR" lamp lit up - reset - goes off then back on etc...  I can hear excess current (60 Hz hummmm) before trip.  It is broken.  I closed the regeneration and pressure build manual valves and shut down the Regeneration Control Panel.  Also the 3-phase CB.  

So for tonight, only the air duct heater associated with the bake enclosure will be heating CP4.   

2350 hrs. local -> Leaving site now.