[time-nuts] HPZ3801 Failure

Joseph Gray jgray at zianet.com
Thu Feb 4 22:32:09 EST 2016


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 <jgray at zianet.com> 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 <paulswedb at gmail.com> 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 <Manuals at artekmanuals.com>
>> 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
>>>>
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>>>
>>> --
>>> Dave
>>> Manuals at ArtekManuals.com
>>> www.ArtekManuals.com
>>>
>>> ---
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>>>
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