[time-nuts] HP Z3801A Internal Power Supply issues

Adrian Godwin artgodwin at gmail.com
Sun Jan 31 16:43:25 EST 2016


A tant melted on one of my KS-246361 boxes (I guess they're a similar age,
possibly even the same source). The only one so far to have trouble. It
failed in such a way that it continued to smoke and load up the power
supply,

The current drawn from the no-name laptop power supply was still well
within spec, at least by the time I post-mortem'ed it. But that melted too,
and took out three levels of circuit breakers. The KS-24361 worked
perfectly after replacing the cap.




On Sun, Jan 31, 2016 at 4:42 PM, Bob Camp <kb8tq at n1k.org> wrote:

> Hi
>
> I had one that took out the internal fuse once every 3 to 5 years. After
> replacing the fuse 3 times, the supply died. Go figure … only 15 years or
> use.
>
> Bob
> > On Jan 31, 2016, at 9:11 AM, paul swed <paulswedb at gmail.com> wrote:
> >
> > 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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