[time-nuts] Z3801A/58503A Help

[William H. Fite]

I have purchased a couple of Tbolts from Yixunhk and they have arrived very
quickly and operated properly.  In fact, while the power supplies were
obviously long in the tooth, the 'bolts, themselves (the "red label" ones),
looked absolutely brand new.  Nary a scuff or scratch and spotless.

I guess it is a crapshoot with these guys.

Bill




On Sat, Dec 11, 2010 at 10:45 AM, Jerry <jreed123 at cox.net> wrote:

> I recently purchased a Z3801A/58503A off of E-bay from Yixunhk in Hong
> Kong.  The unit arrived quickly and was complete with antenna, power
> supply and some software.  It is a nice kooking package with an HP
> case much like the HP3805.  The first problem was that the case was
> marked as requiring a 38-60 volt power supply which seems to be the
> common power supply for the Z3801A.  The power supply that came with
> the unit was a 24 volt power supply.  After a lot a research and help
> from several members of time-nuts I deduced that the vendor had
> changed out the power board in the unit and that it did in face run on
> 24 volts.  In trouble shooting the unit I found several loose screws
> which were likely affecting the operation of the unit.  After I got it
> going I noticed that the EFC voltage plots were jumping all over the
> place and about every 24 hours it would drop out of lock because the
> EFC could no longer keep the oscillator in spec.  More trouble
> shooting revealed that the power to the outer oven was never coming
> on.  There is an output on pin 10 of the cpu that turns on the outer
> oven and this output was never going active.  Some additional research
> found that others have had a like problem and that by pulling up the
> input to the outer oven circuitry they were able to get the cpu to
> reset and work normally.  When I pulled up the input to the oven it
> worked normally but the cpu would never reset.  I have had numerous
> E-mail with Yixunhk and he has been of no help.  It will cost $200 to
> return the unit to Hong Kong.  If anyone has any suggestions I would
> like to hear them.  In the meantime based on my experience I would
> think twice or more about doing business with Yixunhk.  He advertised
> the unit as fully functional and claims that it was fully tested.
> This problem was not caused by shipping damage and any tech with
> experience on this type of equipment should have recognized the
> problem.  Sorry about the long ramble but I thought my experience
> might help someone else.
> Jerry
>
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