Identified two seperate WFD problems today. Expect to fix one
tomorrow, and repaired the other.
First of all, the WFD has been out for a while... the WFD database
should have the run numbers if CHris Walter has had enough time to get it
updated. The problem (after some fumbling) turned out to be the SM 4 WME
_backplane_. How can a backplane break, you ask? Easy... the VME backplane
uses inverted logic (i.e. lines normally float high and are pulled low to put
them in the logic=True state). On a CAMAC crate this is done with pullup
resisitors on the controller, and the backplane is just a bunch of wires. On
a VME crate, however, it's done with two op amps which get +5 V in and hold
the backplane to +3 V. One of these kicked the bucket.
The second problem was a little bit of trouble with HIPT readout which
I discovered (with a lot of help from Chuck Lane) while reconfiguring the
CAMAC highways (it's been a busy week!). Essentially, the latches were not
getting properly reset but it should be OK now.
As of run 10529, we are running with WFD in SM 1-3 and 5-6. We expect
to put SM4 back in tomorrow, but the backplanes are a real pain to work on so
it may take two days.
- Nat