The only thing different with the IC2 (driver, vs. nixie-lighting) present, is that the 5V across the LEDs slowly dies off (I assume because of an additional trickle ground connection within board that is in front of the actual LEDs). The 5V and non-amplifying 12V test points do not change whether IC2 is there or not. I assume IC3 (the high voltage switching chip that connects the nixie cathodes) has no bearing here, since the high voltage is not even getting to it (the circuit does the same things, whether or not it is present).
The fact that 12V still shows on the far side of the amplifying circuit tells me that a short is occurring between the input power side and the output (after replacing it, I do not think the new IRFD220 chip is nonfunctional, nor the capacitors/resistors accompanying it). This is good, since it appears there are very few 12V elements in the circuit, the rest being either 5V or high voltage. Narrows down the possibilities. According to the diagram, the UF4004 diode (D5) is the primary element separating the 220V output of the MOSFET from the 12V input (I am admittedly a bit confused by the circuit diagram representation, but I am guessing high voltage pulses are deflected by the inductor L1 and then flow across the diode D5 where they the remain). I suppose I'll try replacing D5 next, with another +400V 1amp unit (so long as its activation voltage is well below 12V it should still open, right?). The diode does show one-way metering, and a test value of 350, but I just don't see what else could be connecting the 12V and MOSFET outputs. What would cause the MOSFET to generate a gain of 1.0? Given the amount of damage the board is sustaining from all my picking at it, this diode swap is probably the last thing worth trying before starting over (frustrating, since I successfully hooked up a nearly-identical kit a neighbor needed help with, with no trouble whatsoever) TCB On Sunday, January 18, 2015 at 5:11:32 AM UTC-6, Ryan wrote: > HV sense resistors are all good? Have you tried it out with the driver IC > removed? If that's all good and the FET is not shorted, might be an issue > with the microcontroller. > > On Sun, Jan 18, 2015 at 3:12 AM, barnbwt <[email protected] <javascript:> > > wrote: > >> Alrighty, >> I got the C3 and C4 HV circuit capacitors switched out (the closest >> quivalent for the C4 were a considerably higher voltage rating, 35V vs >> 16V. The C3 I found was identical, but a much larger metal-film version >> rather than electrolytic). I also re-flowed all the solder connections in >> the HV circuit components left in place. I don't *think* I'm changing >> anything, but the following appears different: >> >> -The die-off of the circuit seems to happen a bit faster with the new >> capacitors (it reverted when I replaced the new caps with the >> better-fitting originals) >> -The die-off of the LEDs does not occur when the IC2 board is not >> installed (circuit just stays lit, but still not generating high voltage) >> >> I checked all the diodes, and they are still blocking current the way >> they are supposed to (can't measure the figures, though). I also checked >> each soldered connection to the next component in the chain, and nothing in >> the HV circuit is open circuit (bad solder joint/etc.). Looking at the >> diagram, I don't think I can isolate the HV circuit from the rest without >> removing a bunch of components for the LEDs and nixies, so I'm officially >> at a loss for the next step in troubleshooting. Even if I had access to a >> scope I'm certain I don't know how to use it. I'd obviously buy another >> 70$ kit before a 300$ scope, at least until that one cooks, too. >> >> I *think* the fault lies outside the HV circuit (but connected to it, >> thus draining its voltage output to 12V), or I've managed to cook the >> IRFD220 again (which would be surprising, since I took even greater care to >> solder it without overheating this time, and the first go-around actually >> work until the short), or the IC2 chip is nuked and cannot activate (but >> I'm more inclined to think the lack of a high voltage at its sensing input >> is the cause for that) >> >> TCB >> >> -- >> 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] <javascript:>. >> To post to this group, send email to [email protected] >> <javascript:>. >> To view this discussion on the web, visit >> https://groups.google.com/d/msgid/neonixie-l/b97e0a4e-c6ee-42d8-90b3-f14a7f0cc6c4%40googlegroups.com >> >> <https://groups.google.com/d/msgid/neonixie-l/b97e0a4e-c6ee-42d8-90b3-f14a7f0cc6c4%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> >> For more options, visit https://groups.google.com/d/optout. >> > > -- 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/67bbe972-59c4-4f71-86b3-8d31abdd57c0%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
