Transistors arrived today --- I swapped in a new PNP and still no dice. Since the tubes have individual anode resistors, I remain at a loss as to what the problem is. Waveforms did not change.
On the working tubes, I can see the voltage drop across the anode resistor as the tube lights. No such drop across the anode resistors on the non working tubes that share the HV anode driver. Could I really have 2 bad tubes, that just happen to share a driver? Would all the digits fail? I'm tempted to apply my neon sign tester to the tubes to see if they ionize, but I'm a bit fearful about damaging the clock. Any suggestions appreciated. Terry On Saturday, November 12, 2016 at 8:48:27 AM UTC-6, Terry S wrote: > > I did trace the logic level signal from the CPU to the anode driver -- > it's good all the way up to the NPN and past that thru the voltage divider > (although harder to see) to the base of the PNP. So while I am *fairly* > certain the PNP is the culprit, I haven't ruled out a tube yet. Resistors > ohm out good. > > Terry > > On Friday, November 11, 2016 at 9:56:47 PM UTC-6, Dekatron42 wrote: >> >> You might already have tried the ideas below, or already know about them >> but I mention them anyway as I have come across those faults. >> >> You should make sure that you load the driver properly, otherwise it >> might not show its fault as small leakage currents will be present and show >> you the wrong voltage levels. If possible you should disconnect the two >> Nixies, you can do this by unsoldering the end of the anode resistor >> closest to the nixies and hook up a known good nixie to the anode resistor, >> wiring one of the cathodes to the same cathode on the nixies. This way you >> will know that you have a known good nixie there and if it still fails it >> must be some component in the driver chain, all the way back to the >> controller driving the NPN transistor. >> >> You can also unsolder the resistor driving the base of the NPN >> transistor, the end closest to the controller and then hook it up to any of >> the other anode drivers, if the driver works then it is the controller. >> >> /Martin >> > -- 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 post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/2a6d6dca-ac42-4bb3-b6b9-435406bee8bd%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
