CCD pedestals and SSPs


Please note that the pedestals of the CCDs are very sensitive
to power cycling on RF distribution. This distribution module
is located in the readout crates with the SSPs.

You should NOT cycle the power on the crates containing CCD
readout UNLESS ABSOLUTELY necessary. If you are having troubles
reloading SSPs, cycling power does not usually solve anything.
It can actually do more damage by stressing the hybrids.
Please use the RESET toggle switch on the SSPs instead of
cycling power.

If you absolutely need to toggle the power on the CCD SSP crates
or if there is a power glitch in the counting room, the CCDpedestals
will be affected. You need to cycle also the
power on CCD crate 1 bottom, CCD crate2 top and CCD crate3 top.
Then you must wait at least 5 minutes and you must make a CCDped
run. This is not too good for the CCDs.
It explains why you should NOT cycle power on the CCD SSPs
unless absolutely necessary.

If you have to cycle the power as explained above, you must
make an entry into  ELOG  saying you have cycled the power.

Renee Poutissou
March 5th, 2002