Like some others already mentioned, it looks like an issue with the design. So, ordering another one probably wouldn't fix the underlying problem. A "quick" thing you could try is replace the PC817 optocouplers with TLP627's (as mentioned above). Just buy them on aliexpress.com or something - you'll need 6 of them. (try these, you'll get 10 for about 5$ including shipping http://www.aliexpress.com/item/Free-Shipping-10PCS-LOT-Optoisolator-TLP627-1-TLP627-DIP-4/1406962252.html ) You'll have to do some soldering, but it may be well worth the effort! Consider it a fun project. I'd be extremely frustrated having bought a clock, to see that flickering all the time.
Look, the problem with those PC817's is the max. 35V collector-emitter voltage, see this datasheet of the part: http://mkpochtoi.narod.ru/pc817_ds.pdf You can see under "Absolute Maximum Ratings", the Vceo rating of 35V. Now, look in your clock's schematic, and you will see HV (175V) connected to lead #3 (which should actually be #4, but that could be an error in the schematic, hopefully) of the PC817. When the nixie is on, the voltage across 3 and 4 will be close to 0, but when it's off (it's off at least 5/6th of the time: your clock works by multiplexing; only one tube is on at a time, but because this happens really quickly, your eye will perceive them to be all on), it will be higher than 35V, meaning that the 'switch' (a transistor is essentially a switch) won't stay closed well anymore. If it's not closed, the nixie will light up. This is what you see as flickering. The TLP627 works the same as the PC817, but it has a max. Vceo rating of 300V, much more than the 175V you need. (see http://media.digikey.com/pdf/Data%20Sheets/Toshiba%20PDFs/TLP627,-2,-4.pdf) Replacing those PC817's will be a good idea regardless, but it's possible that it's not the cause of your issue (although it would be the main suspect right now). There may be other issues, for instance, you may have microstrip crosstalk, caused by long stretches of high voltage (175V) traces on your PCB running alongside low voltage traces that lead to your PC817's #1 leads. If you post some high resolution photo's of your clock's PCB (the printed circuit board), we may be able to see this (as well as see if leads #3 and #4 are placed correctly or not), but you really need a scope to figure this stuff out. If this is the case, you could potentially fix that by bypassing some of these traces with wires. There may also be a problem with the software that runs on the PIC microcontroller, which you couldn't easily fix without the source, or writing it yourself from scratch. E.g. there may be issues with the order and slight delays in which the anode's and cathodes are enabled. If I were you, i'd either send the clock back and ask money back, or consider it an interesting learning project and try some of the above suggestions. Good luck! Niek On Monday, July 28, 2014 12:47:31 AM UTC+2, Dman777 wrote: > > I really like this clock because of the remote control for the LED lights. > Instead of sending this one back, which would be expensive...I was > thinking about asking the seller if he could sell me another one at a > discount. But, I would only want to buy one that was in correct working > condition. What are the chances the next one would be ok? Is this problem > from design or a anomaly from a flaw in one of the parts? > > Thanks, > -Darin > > > > On Saturday, July 26, 2014 5:45:09 PM UTC-5, Dman777 wrote: >> >> I think I might of caused some confusion....when I say tubes are turned >> off....I mean.....there is a dimmer setting and you can dim them all the >> way to not being on. I see that weird flickering in the back even when they >> are turned on their brightest....but it's barely noticeable because the >> tubes are on full bright. Does this change anything in the diagnostics? >> Sorry, I'm pretty daft to this stuff. >> >> >> >> On Thursday, July 24, 2014 12:49:25 AM UTC-5, Dman777 wrote: >>> >>> I have this strange behavior with my Nixie clock. The right column >>> marker strobes like there is some kind of short. This clock has a timer >>> function where I can turn off the tubes at a certain time. When the tubes >>> go off, that column marker still strobes on. And also, when the 2 tubes to >>> the right of that column marker are slightly strobing on and off with the >>> column marker. >>> >>> What exactly is causing this? And does it mean that the circuitry may >>> not last as long as the life of the tubes? >>> >>> Video 1: >>> Strobing column with tubes on: >>> http://youtu.be/HeQjneaF7AA >>> >>> Strobing column and tubes when tubes are off: >>> http://youtu.be/KKrKTdNek6I >>> >>> >>> Thanks, >>> -Darin >>> >>> -- 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/fcf26654-421c-4bd6-ba52-56e12928abb2%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
