I dont have the same exact scope-clock, but with mine the intensity, focus, and astigmatism adjustments all interplay with eachother. Mine uses an 8SJ31J tube, and there is a test-point where you can verify the HV is correct. It should measure 300V.
On Monday, October 25, 2021 at 5:20:26 PM UTC-7 GEK wrote: > Ok, so I'm stumped (again)... > > I have replaced D35-38, C52, C53, C54, C55, Q1, C51 and U17. > R67, F68, R69, R70 and R71 measure correctly in circuit. > I've confirmed pulsing on the BLNK- signal at 60hz > I've also swapped U5 (74HC74) and U4 (74HC151). > I've swapped the CRT. > > Curiously I need to have the Bright potentiometer (R11) at maximum to get > an image. > Could something in the High Voltage Supply be causing problems with the > blanking? > > On Thursday, October 21, 2021 at 3:05:10 PM UTC-4 Paul Andrews wrote: > >> 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/ >>>> >>>> >>>> >>>> >>>> >>>> ~ >>>> *[email protected]* >>>> >>>> >>>> On Wed, Oct 20, 2021 at 4:16 AM GEK <[email protected]> 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 <[email protected]> wrote: >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> On Oct 18, 2021, at 7:53 PM, Gary Kaufman <[email protected]> >>>>>>>>>> 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 [email protected]. >>>>>>>>>> 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 [email protected]. >>>>> >>>> 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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