Hey guys I got an issue I'm hoping some of my fellow coilers can help me with. Last night I took my sstc coil over to a friends house for the fourth and was wowing everyone with it. Some drunk idiot decided he was gonna run up and touch the Sparks but managed to actually grab the breakout point and then immediately the lights went out. Tripped the breaker the coil was plugged into. There was no Pop or boom or smoke except the breaker in the panel tripping. Reset the breaker and turned it back on. Pop again. Decided to pack it up till I could dive in to when I got home today. So like a worm I plugged it in at home thinkin it would work but it didn't. Lol. Just popped the breaker. Took it apart piece be piece. Found two of four mosfets blown. Drivers where good as well as the 74hc14 inverter. All seemed to be outputting the normal square waves I saw on scope while building it and testing each section. Replaced the two mosfets since I didn't have four spares or I would of replaced them all. Re soldered it all up. Triple checked and fired it up.... Bingo it worked again.......kinda. The Sparks before drunk asshole #1 touched it were around 8-10". Now they are only around 2-3"..... Got the meter out and tested the voltage across the bridge rectifier. Ac side was 124vac. DC side was 100-113.....that's not right. I had tested the bridge as well with diode check and all was well but where did my 160-170vdc go.. No matter it still was working. Started probing with the scope while the bus voltage and H bridge where disconnected and removed from the box. Noticed my GDT wave forms went from square waves with minimal rise and fall to just sharp spikes.... Rewound a new GDT of the same material as the first in the same fashion with same wire and turns. Tested it and the same out put as the first..... Now it seems there is another issue I've yet to track down. On pins 6/7 of ucc drivers the wave is nice and square. But when tested on any of the secondaries of GDT it's just sharp spikes. Not even close to being a square wave. IAlso replaced the .22uf cap with a new .68uf cap with no change. As well as the 74hc14 and ucc drivers with no change. Can't figure this one out or even why it happened. Any body got an idea what may have happened? Also I'm new to having a scope. I want to test the gate of the mosfets while the coil is turned on but I don't wanna blow my scope up. Is it possible to test it while running or without the bus voltage hooked up?
Coil specs:
Primary - 14awg @3 turns
Secondary - 4.5"D/ 10"H(windings) /30awg mag wire.
H-Bridge - irfp260n *4
Drivers -ucc37322/21
Feedback-74hc14
Enclosure is aluminum case.
Interrupter is 555 timer.
Design is based on Steve wards mini sstc with a H bridge instead of half bridge. And few minimal changes to interrupter values. I can make a you tube post of the scope shots of the GDT tomorrow.
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