2017/01/31 (Tuesday)
| Setup: DIB1/3/4 → 3.2 MHz filters → cables → DCRC55(1)/nothing/nothing | |
| 0841 | Tower/MC/Coldplate = 40.9/30.3/190.9 mK, Still = 1.2 K / 0.110 mbar, G1/G2 = 160/160 mbar, 1K Pot = 1.70 K / 32 mbar, Main bath = 69.8%. Boil off rate: slower than slow mode. |
| 0846 | |
| 1109 | Fill LN2 cold trap. |
| 1118 | Investigate DCRC1 heating. Previous experience (when?) (Friday) indicated that turning the FET heater on controlled the temperature (no: turning the 15V Power on controlled the temperature). This time, however, |
| 1200 | Powered DCRC1 up on DIB1 with switchboard inserted and all lines off. Switched all 50 lines on one at a time, but observed no heating. Power cycled DCRC1 with all lines on, no heating. Removed switchboard and powered up DCRC1, heating returns. |
It's a mystery why the heating did not occur when the switchboard was in place with all lines on. However at 13:16 it seems that heating did occur with the same setup.
| 1311 | Perform electrical check on DIB1, everything looks as it should be. No shorts to ground seen. |
|---|---|
| 1316 | DCRC55(1)→Switchboard(all on)→DIB1 Power DCRC1, heating begins. Switch off LED lines, heating stops. But, if you start with DCRC55(1)→Switchboard(all on except LEDs)→DIB1 no heating, even if you then switch on the LED lines. |
One LED on DIB1 (these are on the DIB) is known to be leaky, i.e. there's a non-infinite resistance in the reverse bias. Maybe this one is causing the problem. But it seems to only be a problem if the LED lines are connected during startup.
| 1628 | Start with DCRC55(1)→Switchboard(all on except LEDs)→DIB1, switch on DCRC, no heating. Switch on the LED lines, no heating. Turn on MIDAS DCRC programs, heating begins! Check and reset LED and 15V power setting (was 15V power actually adjusted??) in ODB and in telnet, still hot. |
|---|
Probably turning on the MIDAS programs initiated some startup sequence similar to what the DCRC alone does when you start it.
| 1340 | Start with DCRC55(1)→Switchboard(all on except LEDs)→DIB1, switch on DCRC, no heating. Switch on the LED lines, no heating. Turn on DCRC driver, heating begins. Turn off LED switches on board, heating continues. Turn off DCRC driver, heating stops. Turn on DCRC driver, no heating. |
|---|
this is a bit mysterious.
| 1511 | Fill LN2 cold trap. |
|---|
Note: Similar to yesterday the 15V was ignored on this day. Everything here is still consistent with the fact that for DIB1, the 15V Power needs to be on or else the tower will heat up, assuming the LED lines are connected. Today's results indicate that it's the DIB1 LEDs that are the problem. It also seems to be case that it has something to do with startup routines initiated by the DCRC or by the MIDAS DCRC programs.