The acute-angle traces give it character > On Oct 20, 2021, at 5:04 PM, Terry S <tschw10...@gmail.com> wrote: > > > That may just be one of the worst PCB layouts I've ever seen. >> On Wednesday, October 20, 2021 at 8:33:41 AM UTC-5 martin martin wrote: >> Here's a simple one >> https://www.tindie.com/products/howchon/osc45-oscilloscope-clock-kit-for-many-crt-types/ >> >> >> >> >> >> ~ >> mcve...@gmail.com >> >> >>> On Wed, Oct 20, 2021 at 4:16 AM GEK <geka...@gmail.com> wrote: >>> Will do, Hopefully parts will be here by Friday. I may try and shotgun >>> D35-38 and C52-53 before then as I should have spares around here. >>> >>> Finger's crossed! >>> >>> - Gary >>> >>>> On Wednesday, October 20, 2021 at 1:19:58 AM UTC-4 Tristan wrote: >>>> Hi Gary, >>>> >>>> That's a bit odd. While I'm no EE I would have expected that removing U17 >>>> would have blanked the display if the rest of the circuit was working >>>> correctly. It looks Q13 should be conducting without U17 fitted and the >>>> grid should become more negative with respect to the cathode to ensure >>>> cutoff. I think you may need to look at the D35-38 and C52 & C53. >>>> >>>> - Tristan >>>> >>>>> On Wednesday, October 20, 2021 at 12:42:53 PM UTC+10 GEK wrote: >>>>> Tristan - >>>>> >>>>> Thanks for those hints. the BLNK signal is pulsing at 60hz, and I >>>>> swapped Q13 without any change. I also socketed U17 (6N137) while >>>>> waiting for a replacement to arrive. Removing U17 from the circuit >>>>> leaves the display unchanged, so it does appear that the blanking circuit >>>>> is the culprit. >>>>> >>>>> I'll swap U17 once it arrives - and if that doesn't fix things start >>>>> shotgunning the passives. >>>>> >>>>> Thanks again for the guidance, very appreciated! >>>>> >>>>> - Gary >>>>> >>>>>> On Tuesday, October 19, 2021 at 10:04:24 PM UTC-4 Tristan wrote: >>>>>> Also the voltage between the cathode and the blanking section should be >>>>>> checked (I.e. the voltage across C51) and R65 and R67 should be checked >>>>>> (or potentially replaced along with C51 if shotgunning it). The rest of >>>>>> the high voltage supply appears to be working. >>>>>> >>>>>> - Tristan >>>>>>> On Wednesday, October 20, 2021 at 11:50:56 AM UTC+10 Tristan wrote: >>>>>>> I agree. The blanking is not working and as a result the beam is also >>>>>>> faintly visible as it moves quickly between the characters as well >>>>>>> drawing the arcs. It would be a good idea to check the BLNK signal on a >>>>>>> scope and at least see that is is toggling but my money would be on the >>>>>>> analogue blanking section. Given the other side of the optoisolator in >>>>>>> the blanking section is at a fairly high negative voltage potential (as >>>>>>> this reduces the need for the deflection amps to handle higher >>>>>>> voltages) you will need to be careful when probing around there but I >>>>>>> would start by checking the voltages across C54 and C55 (as long as you >>>>>>> are confident doing so safely with the HV potential to ground). The >>>>>>> correct voltages aren't specified on the schematic but they will be >>>>>>> based on the grid cutoff voltage of the tube. If you wanted to avoid >>>>>>> probing while the clock is on I'd be inclined to shotgun replace that >>>>>>> section starting with the power supply diodes, caps and Q13 and then >>>>>>> U17 and finally the passives and see how you go. >>>>>>> >>>>>>> - Tristan >>>>>>>> On Tuesday, October 19, 2021 at 4:24:11 PM UTC+10 iavine wrote: >>>>>>>> From what I remember: >>>>>>>> the characters are generated from circles, ellipses or lines which in >>>>>>>> turn are created using sun or cosine waveforms >>>>>>>> To make a character the beam is blanked for certain parts eg C is a >>>>>>>> circle with a bit cut out. >>>>>>>> >>>>>>>> Looks like the blanking is not working as you’ve got a lot of circles >>>>>>>> and ellipses there. >>>>>>>> >>>>>>>> Looks cool though >>>>>>>> >>>>>>>> Cheers >>>>>>>> Ian V >>>>>>>> >>>>>>>>>> On 19 Oct 2021, at 06:08, Mac Doktor <themac...@gmail.com> wrote: >>>>>>>>>> >>>>>>>>> >>>>>>>> >>>>>>>>> >>>>>>>>>> On Oct 18, 2021, at 7:53 PM, Gary Kaufman <geka...@gmail.com> wrote: >>>>>>>>>> >>>>>>>>>> I've now got a stable, but scrambled display (see pic's). I think I >>>>>>>>>> have a problem with the shape generators but would appreciate any >>>>>>>>>> help or suggestions you could offer. >>>>>>>>> >>>>>>>>> Nah, that's just Cyrillic Neu Sans. >>>>>>>>> >>>>>>>>> >>>>>>>>> Terry Bowman, KA4HJH >>>>>>>>> "The Mac Doctor" >>>>>>>>> >>>>>>>>> "If only you could see what I've seen with your eyes."—Roy Batty, >>>>>>>>> Blade Runner >>>>>>>>> >>>>>>>> >>>>>>>>> -- >>>>>>>>> You received this message because you are subscribed to the Google >>>>>>>>> Groups "neonixie-l" group. >>>>>>>> >>>>>>>>> To unsubscribe from this group and stop receiving emails from it, >>>>>>>>> send an email to neonixie-l+...@googlegroups.com. >>>>>>>>> To view this discussion on the web, visit >>>>>>>>> https://groups.google.com/d/msgid/neonixie-l/3FBEDB26-E97C-44E2-B088-BDA7DAE4A020%40gmail.com. >>> >>> -- >>> You received this message because you are subscribed to the Google Groups >>> "neonixie-l" group. >>> To unsubscribe from this group and stop receiving emails from it, send an >>> email to neonixie-l+...@googlegroups.com. >> >>> To view this discussion on the web, visit >>> https://groups.google.com/d/msgid/neonixie-l/00c69936-4f04-4a88-8343-f2f7d860135fn%40googlegroups.com. > > -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to neonixie-l+unsubscr...@googlegroups.com. > To view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/39da8dc4-eb48-4815-b039-8974fdf50a95n%40googlegroups.com.
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