It looks like something wrong happened around the PSL front end. One of the PSL channel, C1:PSL-PMC_LOCALC, got crazy.
One of the PSL channel, C1:PSL-PMC_LOCALC, got crazy.
We found it by the donkey alarm 10 minutes ago.
The attached picture is a screen shot of the PMC medm screen.
The value of C1:PSL-PMC_LOCALC ( middle left on the picture ) shows wired characters. It returns "nan" when we do ezcaread.
Joe went to the rack and powered off / on the crate, but it still remains the same. It might be an analog issue (?)
The problem seems to be a software one.
In any case, Kiwamu and I looked at the at the PMC crystal board and demod board, in search of a possible bad connection. We found a weak connection of the RG cable going into the PD input of the demod board. The cable was bent and almost broken.
I replaced the SMA connector of the cable with a new one that I soldered in situ. Then I made sure that the connection was good and didn't have any short due to the soldering.
By looking at the reference pictures of the rack in the wiki, it turned out that the Sorensen which provides the 10V to the 1Y1 rack was on halt (red light on). It had been like that since 1.30pm today. It might have probably got disabled by a short somewhere or inadvertently by someone working nearby it.
Turning it off and on reset it. The crazy LO calibrated amplitude on the PMC screen got fixed.
Then it was again possible to lock PMC and FSS.
We also had to burtrestore the PSL computer becasue of the several reboots done on it today.