Instructions to recover from a Wiener crate failure

The EPICS panel for the Wiener CRate (WCR) in sector 0 is shown on the picture below. Thete are two ways to popup this panel.

:EPICS panel for Wiener crate:
Epics panel for the WCR in sector 0.

As shown on this picture, everything should be green on this panel. Check in particular the crate temperatures (top left) and the fan speeds (bottom right).
About the crate temperatures (Jerome + Nicolas 2006/07): the inlet temparature sensor is in the fan tray and gives the temperature of the air which is being used to cool the boards; the bin sensor measures the air that is leaving the crate after having cooled the boards; the PS temperature is, as expected, the one on the crate power supply.

In case of problem with the crate, press the 'AC Off' button. After a few seconds, press the 'AC On' button. If the crate comes back to life (be patient, epics can sometimes be pretty slow!), everything is fine. Otherwise, there is a problem.

So far the only serious problems we've had with WCRs are some fan failures due to the ageing of these components. There can also be a communication problem between the fan tray and epics which is likely to be due to a wrong canbus address.

Fan failure

Each WCR hosts one tray with 9 fans -- for pictures and explanation, see here. 6 are connected to epics whereas the 3 other ones are not as they were added specially for the DIRC to ensure a better cooling of the crate.

If a fan fails, the crate should trip. Yet, the fan failure signal which comes from a fan monitored in epics is bypassed by default to avoid loosing data: the temperature remains cool even with one fan missing. In addition, any fan failure will trigger an alarm in the DIRC_WCR section of the ALH which will let the DIRC oncall expert know there is a problem.

If one of the 3 fans not monitored in epics fails, the only solution is to change the fan tray. As this operation requires to open one backward door, hours of data will be lost but there is no other way to proceed... If you (as DIRC expert) reach this conclusion, let the RC know asap so that he/she can setup the door opening after having discussed with PEP.

One thing you can try anyway is to lower the requested fan speed. With a fan speed of at least 2000 RPM, the crates seem to operate fine. Lower the fan speed by clicking on the upper, blueish arrow and moving the mouse to the left with the mouse button still pressed.

No communication with the fan tray

If some information related to the fan tray (e.g. the fan speeds) is white on epics, this may mean that the fan tray canbus address is not correct. This is likely to happen just after the fan tray is changed; for more details, see here.


The pilot should inform the DIRC expert of any action on the DIRC WCR.

Web Page created by Thomas Hadig
Last updated on June 27th, 2005 by Nicolas.