From: Eleanor Judd (egjudd_at_lbl.gov)
Date: Sun Mar 16 2003 - 19:03:58 EST
Hi Frank,
Well, we had a short access this (Sunday) afternoon. I unplugged and re-seated the
cable coming out of the back of the TOF TCD. I also wriggled the LEMO connectors on
the front. One of them seemed a little loose.
There has been no beam since then. I have asked the shift crew to add TOF back in
as a test if they get beam tonight, after they know everything else is running
smoothly. If not, then it will get tested tomorrow,
Hope this is OK with you, and sorry again for the delay
Eleanor
Frank Geurts wrote:
> fred bieser wrote:
> > it isn't clear to me if the quoted symptoms are all from a single run or
> > several with consistent results (??) I agree with Bill that if (in several
> > runs) things look good for a while and then go bad it is probably not the
> > cabling; HOWEVER it is not impossible: if half of a differential pair is
> > missing, signals might actually get thru for some time and then become bad
> > thru pumping of the floating line(s). As a hardware guy, I am always ready to
> > blame the software but in this case I know there has been activity in the
> > area and I woiuld guess the software has not changed (?)
> >
>
> Software hasn't changed in a month or so and my analysis of the daq log
> files (see startrg-hn) shows no evidence for hardware problems on the
> TOF logic and readout side: everything runs smoothly up and until some
> random moment during the run. What we see happen at that point is that
> although the Bira generates LAMs all over the place it doesn't find a
> word at its input register. This is most likely *not* a Bira failure
> since the next run it'll operate again and performs exactly like we
> expect. All the raw data we take looks perfect, so -again- I don't see
> any evidence of hardware failures on TOF's side.
>
> We know for a fact that the rear connectors of the TCD can come loose
> (it wouldn't be the first time) and we also know that last Wednesday a
> lot of activity took place at the TCD rack. The rear connector carries
> the word that goes to the Bira input register and that is were we see
> the (random) erratic behaviour. I really think we should check whether
> this connector is properly plugged in.
>
> TOF is dead in the water now for three days ... a quick access of 10min
> is all the trigger folks would need to re-plug the back connector.
>
> -frank
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