It seems that there has been a rash of Z3801A failures lately. Mine has been out of lock for a couple of months, but I haven't had time to look into it. Comparing it against my other GPSDO, it seems that the OCXO is not the problem, as after all this time, it is only 2 Hz off. I'm guessing the GPS board went bad. I'll have to see if they are still available on ebay.
After decades of use, I just can't understand why these things fail :-) Too many projects. Joe Gray W5JG On Thu, Feb 4, 2016 at 8:09 PM, Joseph Gray <[email protected]> wrote: > Wes, > > I just checked and KO4BB already has the power supply info. > > http://www.ko4bb.com/manuals/index.php?dir=02_GPS_Timing/Z3801 > > Joe Gray > W5JG > > > > On Thu, Feb 4, 2016 at 5:21 PM, paul swed <[email protected]> wrote: >> Daves absolutely correct about working around bad supplies. >> The reason for the preregulator is that it would allow the 3801 to meet >> European ETSI dc voltage standards that goes up to 75VDC on the telco >> battery bus. US can reach 56 VDC. >> Anyhow if thats your only problem then you can solve the problem. >> Regards >> Paul >> WB8TSL >> >> On Thu, Feb 4, 2016 at 1:39 PM, Artek Manuals <[email protected]> >> wrote: >> >>> Wes >>> >>> Some one reversed engineered the supply about 10 years ago and they posted >>> the schematic on the WEB....The web link I have no longer works so I will >>> email you the schematics of the supply direct. >>> >>> I will check to see if the files are not already up on KO4BB and if not I >>> will post them up there for every one >>> >>> >>> That being said while troubleshooting my own supply this week I have >>> learned the following >>> 1) The supply ( is not a switcher) can be troubleshot on the bench >>> removed ( and unplugged from from the Z3801A. >>> 2) The supply is basically A pre-regulator and two DC-DC converters.By >>> cutting one trace you can separate the two and bypass the preregulator >>> which seems to me to be overkill if you using a good regulated DC supply to >>> feed the thing 36 or more volts into the DC/DC converters is fine >>> 3) The smaller DC-DC converter supplies 5V only ( probably for the >>> receiver ???) >>> 4) The larger Lucent converter supplies =15V / -15V /+5V >>> 5) all the DC-DC outputs can be supplied with separate DC supplies of good >>> quality >>> >>> >>> >>> Dave >>> NR1DX >>> ArtekManuals.com >>> >>> >>> >>> >>> >>> >>> On 2/4/2016 12:17 PM, Wes Atchison wrote: >>> >>>> My HPZ3801 has died. It appears the internal DC to DC converters have >>>> died. >>>> The fuses (4) I have found on the boards check good with an ohmmeter. I >>>> have checked voltage on test points where labeled as a supply. No >>>> voltages >>>> present. Is there a schematic available somewhere? Has anyone repaired a >>>> Z3801 with similar problems? >>>> >>>> Thanks for any help. >>>> >>>> >>>> >>>> 73, >>>> >>>> Wes >>>> >>>> WA5TKU >>>> >>>> _______________________________________________ >>>> 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. >>>> >>>> >>> >>> -- >>> Dave >>> [email protected] >>> www.ArtekManuals.com >>> >>> --- >>> This email has been checked for viruses by Avast antivirus software. >>> https://www.avast.com/antivirus >>> >>> >>> _______________________________________________ >>> 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. >> _______________________________________________ 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.
