RBA test fine, then doesn't

[pawn94523]

New to the forums, Thanks for having me.

I have been rebuilding for about two months now and have run into a problem lately.

First of all...I have a kangertech subtank running on a evic VTC-Mini

The problem I have is that whenever I build a coil(the same as i have been doing for about 6 weeks) it appears to have an ohm of between .4 and .5 on my ohm tester. I put it on my device and the device reads the same. Then I add the liquid(let sit for 10 minute or so) and then try to use it. My device reads "low atomizer" which I have read means that the ohm is probably below .1(the lowest my device recognizes). I have used a couple of different ohm testers from friends and the same problem pops up. About 1 in 6 coils works. Is there something I am missing?

 

[edyle]

my guess is you are starting out in tc mode and the mod is kicking into wattage mode.

 

[BillW50]

See my Ni200 build on a Subtank RBA?

The wire captured on the top is ground. That doesn't matter if it touches the sides of the RBA cap. Now the one on the bottom connects to the 510 pin on the bottom. Notice that this lead is as short as possible without extending passed the side (it does a tad which isn't very good). But when you put the top of the RBA, that lead could touch the side and create almost a dead short. And this is the first thing I would look at.

 

[pawn94523]

Thanks guys! BillW50, i am pretty sure that was my mistake.

 

[tedigram]

Yeah, checking for that kinda short is a good habit. Fortunately it's relatively easy on most attys. Just measure the resistance without touching any part of the tank, then measure it again with your finger touching some part of the metal that's directly connected to the deck. The chimney is the best place obviously, but sometimes you can't reach it with the tank assembled enough to get the chimney in position.

If the resistance drops noticeably (i.e. more than a few hundredths of an ohm, which could just be meter inaccuracy) then you know that you've got coil touching body metal somewhere.

*edit* the "few hundredths is okay" thing is only true if you're building above .4-.5. Below that, in super-sub-ohm territory, the hundredths start to actually mean something. But in that case you should be using a hyper-accurate meter anyhow.

 

[zoiDman]

Thanks guys! BillW50, i am pretty sure that was my mistake.

Another thing that can Happen is if the Coil is sitting Too High on the Posts, it could touch the RBA Cover.

I ran into this once and it was kinda Maddening. Because it Ohm-ed fine on my tester. And the Screws were Tight and the Leads trimmed Close. But when I would put it together it wouldn't work.

Took me a Few Iterations (and a Few Choice Words) to figure out what was going on.