Hah yes. I have one of its brethren that is even more 'eclectic'. On Wednesday, October 20, 2021 at 8:04:03 PM UTC-4 Terry S 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 >>>>>>>> >>>>>>>> <https://groups.google.com/d/msgid/neonixie-l/3FBEDB26-E97C-44E2-B088-BDA7DAE4A020%40gmail.com?utm_medium=email&utm_source=footer> >>>>>>>> . >>>>>>>> >>>>>>>> -- >>> 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 >>> >>> <https://groups.google.com/d/msgid/neonixie-l/00c69936-4f04-4a88-8343-f2f7d860135fn%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- 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/413fbb95-97c1-4c77-91fd-901c185d8b58n%40googlegroups.com.
