DOM Hub Filter Card Revisions
The DOM Hubs that use REV 0 DOR cards require filtering on the +48V and -48V switching power supplies in
order to protect the communications front end from the typical switching noise, and ripple produced by
these supplies. The DOR cards could be used with quieter, series pass regulators, however conversion
efficiency would be sacrificed, as well as space.
The DOM Hub filter card was layed out with the assumption that the board would only be supported by
stand-offs at the corners, and that no shield would be installed over the top of it. Plans were,
however, revised. The work-around for Rev 0 cards is to file a flat place on the side of one of the four
stand-off to create clearance for the 4-pin power connector.
In order to simplify the support a top shield cover, it is necessary to move the disk drive connector down
about 0.1" to make room for an above the board standoff. As often happens, the movement of one component
forces others to move as well.
Disk Power Connector
It was noted that the pins of the four-pin disk-drive power connector were layed out in reverse order. For
Rev 0, the work-around is to place the socket on the back side of the board.
In Rev 1, the pin order is reversed in the layout.
The footprint for the large, through-hole filter capacitor were sized for a typical standard part from the
For Rev 1, the diameter of the drilling of the pad stack were increased to allow the surface mount
capacitors to be modified so that they could be soldered to the through-hole capacitor footprint.
It was discovered that the current meters read incorrectly for two reasons: the wrong decimal point was
lit, and an analog return pin on the meter was incorrectly connected to a return net.. The Rev 0
work-around for both problems was to remove the pins from the filter board connector, combined with the
jumpering of connections on the back of the meter itself.
In Rev 1, the decimal point pins now connect to jumper footprints, allowing the decimal point to be
selected at assembly time. The offending return pin is now left to float.
Revisions were completed May 14, 2004. G. Przybylski, LBNL, for IceCube