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 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 <[email protected]> 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 <[email protected]> >> 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). >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to https://www.febo.com/cgi-bin/ >>> mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >>> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/m >> ailman/listinfo/time-nuts >> and follow the instructions there. >> >> > -- > Howard L. Davidson > [email protected] > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/m > ailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
