Here's a simple one https://www.tindie.com/products/howchon/osc45-oscilloscope-clock-kit-for-many-crt-types/
~ *mcvei...@gmail.com <mcvei...@gmail.com>* On Wed, Oct 20, 2021 at 4:16 AM GEK <gekauf...@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+unsubscr...@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. 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