[time-nuts] HP Z3817A Reverse Engineering
ed_palmer at sasktel.net
Mon Jan 9 19:00:09 UTC 2012
Thanks for the correction, Bruce. I made the mistake of thinking that
the Bridge Section was the only thing inside the puck. I should have
On 1/9/2012 12:47 PM, Bruce Griffiths wrote:
> Ed Palmer wrote:
>> On 1/9/2012 8:58 AM, Robert Benward wrote:
>>> Hi Ed,
>>> I just tracked down Fluke and he offered me one, and per your advice
>>> I will try and confirm the condition before purchasing from him (not
>>> that there are alternate sources) .
>> I have to say that fluke.l did guarantee that the E1938A was alive
>> and it was. According to other messages on this list, he's been very
>> good about replacing defective items.
>>> I have the schematics, but taking apart the hocky puck is another
>>> matter, I pry and pry but get nowhere. I don't think it was
>>> designed to take apart. What buggs me is that if I warm up the oven
>>> and stimulate the oscillator with an external signal, it will
>>> oscillate. So it DOES work, and if I go into the puck to trouble
>>> shoot it, I probably won't find anything defective.
>> Are you certain that the problem is inside the puck? If I'm reading
>> the schematic correctly, the only thing in there are the crystal and
>> a few passive components. The oscillator circuit is on the external
>> board. A bad connection or failed component could be interfering
>> with the oscillation. When the puck is hot, it's almost able to
>> overcome the external problem and your stimulus signal is enough to
>> get it going.
> Wrong, the oscillator is within the oven, its buffer amplifier is
> outside the oven.
> Everything shown on the first schematic is inside the oven.
>> When your E1938A is working, is it working properly, on frequency and
>> good stability? If so, that would suggest that the crystal is okay.
>> The problem could be nothing more serious than a bad solder joint.
>> I've noticed that precision oscillators have something of a 'diva'
>> personality and can be quite temperamental. I have an Oscilloquartz
>> BVA oscillator that takes 5 - 10 seconds to start up after you apply
>> Have you asked Rick Karlquist for advice on dissecting your E1938A?
>> He's an active member of this list and one of the designers of the
>> E1938A. You might want to start a new message thread called
>> something like 'E1938A repair' to get the attention of the right people.
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