[time-nuts] HP Z3801A Internal Power Supply issues

paul swed paulswedb at gmail.com
Sun Jan 31 09:11:56 EST 2016


As I mentioned in the another thread this week.
You can indeed replace the failed voltage with just another inverter.
Mine has run this way for 10 years. Mine was a 5 by the way. If it was one
side of the +/-15 I would say you want to replace both.
The entire switcher can be replaced with supplies that work off of 110 so
you can get rid of the 48 volt supplies.
Good luck
Paul
WB8TSL

On Sun, Jan 31, 2016 at 12:04 AM, Alex Pummer <alex at pcscons.com> wrote:

> power supply runs for a while, output current increases, but voltage stays
> correct -> problem is in the load circuit, load circuit working for a while
> load current increases, but it recovers after pause -> look for some
> tantalum capacitor in the load circuit, they recover often  a few times
> before they finally die,
> KJ6UHN
> Alex
>
> On 1/30/2016 6:21 PM, Artek Manuals wrote:
>
>> My Z3801A began to die over the last few days. It would work for an hour
>> or two then produce a receiver error and communications problems. Turn it
>> off, let it sit awhile, back on and it would start the survey and then
>> begin to recover. Tonight it finally went dead with high current on the
>> main input . The feed supply has a 2amp current limit so I have not blown
>> the two 3amp fuses
>>
>> I have a schematic of the supply reverse engineered by Stefan Hegnauere a
>> few years ago (thank you very much) and a limited theory of operation
>> description so I am not totally dead from a troubleshooting point of view
>> although if one of the DC-DC converters is dead then I will likely have to
>> scrap the supply
>>
>> Questions
>> 1) Any prior experience as where to look first I checked the
>> electrolytics and at first glance they seem fine, no loss of magic smoke or
>> any parts obviously hot or bulging. ESR 's look good on those
>> 2) Will this supply function unloaded while I troubleshoot it on the
>> bench out of the unit?
>> 3) Anyone tried independent powering the Z3801? looks like two 5V
>> supplies and +/- 15V..not hard to to do
>> 4) Anyone with a good supply from a parts unit want to part with same?
>>
>> Dave
>> NR1DX
>> ArtekManuals.com
>>
>>
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