Nixie All In One- 2 tubes not lighting up

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2 years 2 weeks ago #8656 by Grundlenuts
ok, so I did the tests that you guys recommended and tubes 4 and 5 still do not light up. I pulled out the optos, positive probe to +5v, negative to socket pin 2, and all 6 are right at 4.95v. With the optos installed and clock powered I checked ground at each pin 2 and that was good. I pulled the optos again and shorted pins 3 and 4 with a jumper and each tube lit up and each test (one at a time). I also went through 10 feet of desolder braid yanking the socket out. That was fun. No shorts or bridges under the socket. I tried setting OK4 opto on the through holes and the tube did not light up when powered on, so it wasn't the socket. Now I'm really confused. R20 and R21 are the correct value. I will check resistance on those resistors when I get home from work.
Thanks for all the help.
Mike

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2 years 2 weeks ago #8657 by Ty_Eeberfest
Let me make sure I'm reading you right: are you saying that all 6 tubes lit up (one by one obviously) when you jumpered pin 3 to pin 4 on each opto? If yes, then all that is left is the 1K resistors (assume you meant R19 and R20), board traces, and the micro itself. Which leaves me wondering if we are seeing another case of failed microcontroller... rare but there has been at least 1 I know of in the last month or two.

If you want to get a bit hackish about it I suppose you could bend pins 3 & 4 of the micro so that they stick out to the side rather than go in their socket spins. Or to say it another way, disconnect micro pins 3 & 4 from the board somehow while leaving the other 26 pins connected. Then with clock running poke pins 3 & 4 of the socket, form the back if necessary, with a +5v jumper. See if the respective tubes light up.

If the above is unclear, take a look at the schematic. We know the HV side of the optos is good. This new test would check the LV control side of the optos all the way back to the micro. The reason for bending out the pins is because as far as I know the micro does not tri-state the pins - they are either +5 for ON and pulled to ground for OFF. So jumpering a pin that's pulled to ground would ne a rather bad thing to do.....

Look into it later when the dust is clearing off the crater.

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2 years 2 weeks ago #8658 by Ian
My money is on the controller, like Ty says, there have been a couple of cases of this over the past weeks, which is new. Either there is something on the boards which leads to the controllers to be damaged, or the controllers are coming out of the factory with errors. I don't check the controllers pin by pin at the moment, but I think I need to make a test-bed with a ZIF on it to pre-check the controllers... :-/

At this point, I think the only reasonable thing to do is to send a replacement controller to you. Want to send me an email with your address (my email address is on the packing slip) and I'll get it on the way...

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2 years 2 weeks ago #8659 by Grundlenuts
I think I’ll take you up on the new controller. I tossed the packing slip but I’m assuming the address is This email address is being protected from spambots. You need JavaScript enabled to view it.?

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2 years 2 weeks ago #8660 by Ty_Eeberfest
Yeah, this is looking a lot like what we went thru on SGottschang's Thread last month. Wonder WTF is going on here?!

Ian, do you know if the Modular I have has a controller form the same batch? Soon as I get the tubes finished up I can start a burn-in just for curiosity sake. If it dies we have one more data point so to speak, and I have plenty of 328Ps here to replace it.

Look into it later when the dust is clearing off the crater.

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2 years 2 weeks ago #8662 by Ian
Shock horror. You threw the instructions away???? ;)

Yep, that's the address...

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