[time-nuts] HP 5275A

paul swed paulswedb at gmail.com
Tue Nov 8 20:15:35 EST 2016


Looks nice and it appears the unit is actually quite clean.
Looking forward to the 9815 porn. Better watch someone may be reading this.
Regards
Paul
WB8TSL

On Tue, Nov 8, 2016 at 8:08 PM, Adrian Godwin <artgodwin at gmail.com> wrote:

> I'm pleased to report this TIC is now running again (albeit with some
> temporary hacks, such as a 7915 regulator).
>
> There were a couple of dried-out electrolytics, the shorted series-pass
> regulator referred to above, and an open-circuit 2N708 controlling the
> timebase gating. Another 2N708 died when I failed to push a PCB fully into
> its socket. They're rather delicate flowers - Silicon, but only 15V Vceo :
> a bit tight when used as switches with a 15V or 13V rail. Replaced with
> BC237s, though that's perhaps a bit slow.
>
> This is the HP5275A from france that  Poul-Henning Kamp mentioned in march
> 2015. It's been sitting here a while waiting for some attention
> ‚Äč
>  VID_20161109_003111.mp4
> <https://drive.google.com/file/d/0B8q6sqvuGdFfMDI2aXA0NnFWRTg/
> view?usp=drive_web>
>
>
> Paul Swed : I'll add some HP9815 porn when I get it reading the 5275A
> outputs.
>
>
> On Mon, Nov 7, 2016 at 2:46 AM, Howard Davidson <hld42 at att.net> wrote:
>
> > The real hack in the 5245 Nixie tube decoder is that the neon lamps were
> > the memory element.
> >
> >
> > hld
> >
> >
> >
> > On 11/6/2016 2:15 PM, paul swed wrote:
> >
> >> Don't know what to say on the transistor. It may have been actually made
> >> that way. They did lots of things back then. Yes familiar with the bcd
> >> decoder its used in the 5245 class counters also. I think someone was
> >> doing
> >> some funny stuff at lunch time to come up with that. It was the 60's
> after
> >> all.
> >> How about some pix of a 9815 calc. That would be pretty neat.
> >> On really old stuff if you can't find the part needed its pretty easy to
> >> replace the whole function with modern answers. I know it sort of breaks
> >> the original mode but for me at least its a case of getting it going.
> >> Regards
> >> Paul
> >> WB8TSL
> >>
> >> On Sun, Nov 6, 2016 at 1:59 PM, Adrian Godwin <artgodwin at gmail.com>
> >> wrote:
> >>
> >> Slightly off-topic, as this is a general repair question. But it's a
> TIC.
> >>>
> >>> I'm repairing a 5275A timer (all-discreet count logic to 100MHz, neon
> >>> bulb
> >>> display, a most amazing bcd to decimal decoder made from neons and
> LDRs,
> >>> 1-2-2-4 decade counters ..) and the current problem is a 2n1038-2
> >>> germanium
> >>> T05 transistor in the power supply.
> >>>
> >>> It's mounted in an aluminium bush which is then isolated from the
> >>> chassis.
> >>> I don't think the bush is also a collet but I can't see how to remove
> the
> >>> transistor. It resists ungentle pushing .. should I push it with a
> >>> hammer ?
> >>> Or is there a kinder way ?
> >>>
> >>> (I'm hoping to eventually put this into a system with a 101A oscillator
> >>> and
> >>> a 9815A calculator to measure the ADEV of a Boule electric pendulum
> >>> clock).
> >>> _______________________________________________
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> >>
> > --
> > Howard L. Davidson
> > hld42 at att.net
> >
> >
> > _______________________________________________
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> > and follow the instructions there.
> >
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