[time-nuts] Errors on HP 58503A GPS time & frequency reference receiver bought from yixunhk.

Azelio Boriani azelio.boriani at gmail.com
Thu Dec 11 18:00:12 EST 2014

If all the voltages and currents are odd, there is the possibility
that the measurement A/D converter or its voltage reference (if
present) is faulty...

On Thu, Dec 11, 2014 at 10:46 PM, Dr. David Kirkby (Kirkby Microwave
Ltd) <drkirkby at kirkbymicrowave.co.uk> wrote:
> On 11 December 2014 at 01:10, Bob Camp <kb8tq at n1k.org> wrote:
>> Hi
>> I suspect that if you look closely at the board in the unit, it’s got water stains on it ….
>> Bob
> I suspect you might be right Bob, but I am not going to break the seal
> to open it up to find out. I will be contacting the seller, to see
> what they offer.
> Does anyone have any experience with these having the voltages going
> unstable? These two log entries show the 15 V is going both too high
> and too low.
> Log 004:20141017.00:00:11:  15V is out of tolerance, value: 16.62
> Log 007:20141017.00:00:11:  15V is out of tolerance, value: 13.78
> This shows the 5V rail has gone too high
> Log 078:20141210.00:00:11:  5V is out of tolerance, value: 5.54
> This shows the oven current is out of spec - whether it is too high or
> too low is anyones guess
> Log 022:20141205.04:42:26:  Primary oven current is out of tolerance,
> value: 115.81
> I'm guessing the 115.81 is mA, but I don't know. If it is mA, 116 mA
> doesn't seem an unreasonable number. I assume this will have an
> oscillator "similar" to a 10811A - lets not worry about the exact
> type. According to the data sheet for the 10811A, the oven resistance
> has a minimum of 42 Ohms. Supply voltage is 20-30 V. So a quick
> calculation shows the turn-on current could be as high as 30/42 =  714
> mA, so 116 mA doesn't sound unreasonable. The 10811A data sheet says
> the power consumption is typically 2 W steady state at 20 V. So that's
> a current of 0.1 A @ 20 V, so once again, 116 mA seems quite normal
> for a steady state value, and a bit low for heating up.
> I've not opened a case on eBay yet. I will do at some point, but would
> like to know the likely fault on this. The fact it does actually work,
> probably indicates there's nothing too serious wrong with it. I
> suspect a cap(s) is failing, which is quite common with age, and
> fairly easy to fix.
> Having looked carefully, there are a few tell-tale signs this case is
> actually not an original HP one, but I am not overly bothered by that.
> It looks good, and if the unit worked, I would be happy.
> It is rather annoying that people leave this seller positive feedback,
> or no feedback if they get their complaints resolved. I've had a few
> people email me about this seller, but they all seem keen not to say
> anything on a list, and looking at the feedback of the seller, it is
> still 100% positive. There is definitely something fishy about this
> seller, but the 100% positive feedback does not reflect that.
> I also wonder why they cleared the log, as the first log entry shows
> Log 001:20141017.00:00:00:  Log cleared
> I wonder if they had problems that they thought they had solved?
> Dave
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