[time-nuts] Z3805 utility, Was: AW: (no subject)
jimlux at earthlink.net
Sun May 23 17:47:43 UTC 2010
Bob Camp wrote:
> The Symmetricom 3805's have an area on the lower board right behind
> the "control" DB-25. It's very similar to the 3801. There are three
> rows of holes for 0.025" post connectors. One row pair is labeled
> RS-232. The other row pair is labeled RS-422. The original intent
> appears to be to jumper the unit for what ever standard the customer
Such was the case on my 3801.. 10 minutes work with a soldering iron and
some wirewrap wire, and it was converted from RS-422 to RS-232.
It's not at all clear that the later units are even stuffed
> for the RS-422 option. There are a number of unstuffed IC locations
> on the pc board.
> Your unit sounds like it's either blown, or running RS-422. I have
> never seen one of the earlier HP 3805's so I don't really know how
> much they have in common with the older units. There are indeed USB
> to RS-422 converters out there that will run on a normal PC.
But unless you're running long wires, or happen to have a RS422
differential system, why bother. If all you're going to do is hook up
the PC to check it out, RS232 is much easier to come by.
More information about the time-nuts