If you remove those "zero ohm" resistors, you need other jumpers to make it work as an RS-232. When I did mine, I stuck in two strips of "headers" and used those HD jumpers to select RS-232 or RS-422.
Check out this site: http://www.ad6a.com/Z3801A.html 73, Dick, W1KSZ -----Original Message----- >From: Robert Benward <[email protected]> >Sent: Jun 13, 2010 8:01 PM >To: time-nuts <[email protected]> >Subject: [time-nuts] My stubborn Z3801A > >To All, > >An update to my Z3801A saga. > >Summary: As you know, I purchased this Z3801A at the Dayton Hamfest. The >person who sold it to me said it was modified for RS-232. I powered the >unit up and the only thing it ever did was go into the holdover mode. Tried >hooking RS-232, but got no response. Did some reading and found the little >green blinking light was a good thing, all the others indicated a failure in >ram, rom, etc. Boot was good if all the front panel lights went on in >sequence. > >Update: Took the unit apart to do some serious trouble shooting. Found the >signals (logic side) on the RS-232 did not go all the way to ground. Subbed >in another RS-232 transceiver, still no luck. Found another note on the >internet about removing the 5 little zero ohm resistors on the bottom to do >the RS-232 conversion. Looked on the bottom and they were still there!!! I >removed them and the signals now went all the way to ground and appeared to >be normal. Tried various programs to link up (GPS.EXE, SatStat, RS-232 >comm). Saw the commands going in, and I did see a response from the Z3801A, >but the computer could not read the response. Since I did see a response >from the Z3801A on the scope, I figured it was receiving commands. I hooked >up an antenna and sent a survey command. Apparently if the GPS is moved (I >don't know how much) the Z3801A needs to do a survey otherwise it won't >lock. I went shopping, and came back about 2 hours later, and low and >behold, a GPS LOCK!!! > >Still to go: The RS-232 signals look fine going into the cable, +/-5V, any >ideas why the computer won't read it? Am I missing something? I tried two >different ports in case I screwed one up one of the ports, but no luck. > >Bob >AC2AZ > >_______________________________________________ >time-nuts mailing list -- [email protected] >To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
