I should have said if I see oscillation from the 7805 that Jeff mentioned, pointing to a bad C1. I may just replace it regardless.
Kiran On Saturday, March 28, 2015 at 7:55:48 AM UTC-4, Kiran Otter wrote: > > Hi folks, glad to find this group! > > I've had a Tubehobby clock for several years, the NCV2.1 with the IN-18 > tubes. In the past Jonas has helped, and I even shipped him the main board > for him to repair, but he hasn't responded to my last request for help, so > I thought I would ask here. > > Recently, I started to notice that other digits in the tubes were > partially lighting up, and eventually the fuse blew. My assumption was > that the K155ID1 drivers had started to go, so I ordered six of them off > eBay, and tried replacing them.. which isn't hard, everything is socketed. > Well it didn't help, so I contacted Jonas. Jonas suggested replacing C6, > which I did and it appeared to fix the problem. > > Maybe a month later, I started to notice the left most digit was faintly > showing numbers, and seemed to be influenced by the next to right digit. > So I thought perhaps the drivers I got from eBay weren't good, so I swapped > them around, trying to see if it made any difference. Unfortunately, I > trashed the two original driver chips that came with the kit. So far > swapping the drivers around among the six I have, hasn't changed anything.. > or if it has, the digits lighting that shouldn't be have moved from tube to > tube. > > Well I let the clock run like this for a week or so, and one day I just > happened to feel around the voltage regulator U1 (L7805CV).. and it's > blazing hot. I put a temp probe on it and it's running at 140F in open air, > and when I built the clock, I epoxied a heatsink to it. It never ever used > to get this hot. In fact the clock has run for years in a closed enclosure > with very little ventilation. It just never produced much heat at all. I > swapped both driver chips for two others, and it still gets just as hot. > > When the clock shuts off the display at night, the temp drops to just > above room temperature. > > So my guess is has to be one of two things I replaced; C6, or the driver > chips. I think it's the drivers, and I'd like to get a pair from somewhere > reputable so I can at least rule them out as the problem. I've seen some > that appear to be ceramic, instead of plastic cased.. claimed to be > 'milspec' but I donno if that's BS or what. > > Any help is appreciated! > > Kiran > > > > > -- 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/db144a82-9537-4bb7-9a3b-6f1536af8c65%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
