[time-nuts] OT: Question on dead HP34401

paul swed paulswedb at gmail.com
Mon Dec 17 14:11:35 UTC 2012


So we are on the same page
You tie the reset through a 1 K r to vcc and you still see the reset signal?
And you do not see the 7 Khz coming from the switching regulator??
Thanks

On Mon, Dec 17, 2012 at 2:57 AM, Ulrich Bangert <df6jb at ulrich-bangert.de>wrote:

> Gentlemem,
>
> pardon for the delayed answer, I had some extreme busy days the last week.
>
> > The floating logic is reset by the LM2925 5V regulator reset
> > output. There is no connection to this reset line aprt from
> > the Gate array reset
> > input and the micro (80196) reset input.
>
> Yes, U553 on page 9-15 has this reset output which is called XPONRST. After
> it has passed the lowpass R503/C504 on page 9-13 (upper left) it enters
> U500
> and U501. I observe this 7 kHz reset signal RIGHT from the lowpass even if
> I
> lift up the voltage regulator's reset output pin.
>
> Best regards
> Ulrich Bangert
>
> > -----Ursprungliche Nachricht-----
> > Von: time-nuts-bounces at febo.com
> > [mailto:time-nuts-bounces at febo.com] Im Auftrag von Bruce Griffiths
> > Gesendet: Dienstag, 11. Dezember 2012 22:46
> > An: Discussion of precise time and frequency measurement
> > Betreff: Re: [time-nuts] OT: Question on dead HP34401
> >
> >
> > It only resets the earth referenced micro (8051) on power up and when
> > pulses on the optocoupler output arent present.
> > There is no other connection to the reset pin of this micro.
> >
> > The floating logic is reset by the LM2925 5V regulator reset
> > output. There is no connection to this reset line aprt from
> > the Gate array reset
> > input and the micro (80196) reset input.
> >
> > The relay drivers are reset by a 80196 output pin.
> >
> > The display logic is reset by another 90196 output pin.
> >
> > Bruce
> >
> > paul swed wrote:
> > > OK but why would it tie to the reset line?
> > >
> > > On Tue, Dec 11, 2012 at 3:48 PM, Marco IK1ODO
> > -2<ik1odo at spin-it.com>
> > > wrote:
> > >
> > >
> > >> At 21:40 11/12/2012, you wrote:
> > >>
> > >>
> > >>> Two comments the manuals available on agilent
> > >>> What on earth is a crossguard?
> > >>>
> > >>>
> > >> Data exchange between a floating, guarded circuit and a ground
> > >> referenced one?
> > >>
> > >> Marco IK1ODO
> > >>
> > >>
> > >>
> > >>
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