The Panaplex display most probably sees the whole voltage span 56V + 137V = 193V, the circuit is just built this way to provide lower voltage to the MK5017 and as bias voltages for the transistors driving the display. Have a look in the book I mentioned above, if you haven't done so already, on page 74 you can see a transformerless design but with similar voltages and design for the MK5017.
/Martin On Sunday, 24 January 2021 at 22:17:26 UTC+1 N9KTW wrote: > Here is the latest: > > 1 Swapped out the caps on the power supply board, and noted voltages (they > dont seem right for an SP-352, IIRC it needs at least 170V) > 2 Drew a power supply schematic (which I have attached) > > At this point does anyone know will the SP-352's even fire at 135 Volts? > If so, Maybe I have a bad 5017 chip...... > > Any ideas????? > > Howard > > On Monday, January 18, 2021 at 9:12:55 PM UTC-6 gregebert wrote: > >> Have you checked/replaced the electrolytic caps ? I've had one fail as a >> short-circuit; coincidentally, that was in a Heathkit but it was a scope >> calibrator. >> >> On Monday, January 18, 2021 at 7:01:09 PM UTC-8 martin martin wrote: >> >>> Hi have the same 6 digit Heathkit. I do have the complete schematic if >>> you need it. My issue (not solved yet) is the power transformer runs too >>> hot to touch. All my voltages are good and the clock still keeps time - I >>> built it back in '77 >>> >>> On Sunday, January 17, 2021 at 11:33:47 PM UTC-8 Dekatron42 wrote: >>> >>>> There is one MK5017 clock that uses PNP transistors in the book I >>>> scanned which you can download from here: >>>> https://groups.google.com/g/neonixie-l/c/Ov-mzZ_pDig/m/G95NMJPKBQAJ it >>>> doesn't seem to use SP352s but at least a Panaplex display. >>>> >>>> /Martin >>>> >>>> On Monday, 18 January 2021 at 04:59:28 UTC+1 N9KTW wrote: >>>> >>>>> Yes, thank you I have seen it. I am currently trying to make a >>>>> schematic of the power supply that is on the clock that I have. I have no >>>>> voltages higher than about 125 ish in the clock. The 15Volt for the chip >>>>> is derived from a zener on a 55 Volt line. Also Heath uses NPN >>>>> transistors , and my unit is using PNP's. I am going to look and see if >>>>> I >>>>> have any other panaplex clock diagrams ....... >>>>> >>>>> Howard >>>>> >>>>> On Sunday, January 17, 2021 at 7:23:39 PM UTC-6 J Forbes wrote: >>>>> >>>>>> did you see this? >>>>>> >>>>>> http://www.decadecounter.com/vta/pdf/gc1092d_schematic.pdf >>>>>> >>>>>> >>>>>> On Sunday, January 17, 2021 at 3:35:14 PM UTC-7 N9KTW wrote: >>>>>> >>>>>>> Well I found another clock to work on, using SP352 displays........ >>>>>>> It is marked DIGITAL CONCEPTS CORP, EC102 electronic calendar clock. >>>>>>> >>>>>>> It uses 3 SP352's for a 6 digit display. A MOSTEK 5017BA chip to run >>>>>>> things. >>>>>>> >>>>>>> The display doesnt light up, at all. In attempting to check >>>>>>> voltages, I cannot find any above about 125 (this seems VERY low for >>>>>>> the >>>>>>> panaplex displays) I have been told that this is similar to a HEATHKIT >>>>>>> GC1092d. >>>>>>> >>>>>>> Anyone got any ideas, maybe a schematic for this guy????? >>>>>>> >>>>>>> T I A >>>>>>> >>>>>>> de Howard, N9KTW >>>>>>> >>>>>> -- 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/0d9f8d5f-213a-48e6-8834-c7eaaf416cfbn%40googlegroups.com.
