Russian 91% v2 irratic resistance readings

[carrielsal]

The R91v2 recently started shipping. One of the new features is a spring loaded center pin. On the surface this sounds like it would be a major improvement. I have now built 2 simple horizontal micro-coils and resistance is continually changing.

Initially I thought the center pin may not be tight enough. The v2 comes with its own spanner tool to tighten the pin. I held the positive block in place with a pair of needle nose pliers and used a small pair of vise grips with the spanner tool to tighten the center pin, so the connection is secure. The positive block does not move when its screw is tightened.

I have seen this issue reported in another forum. Has anyone else experienced this problem and found a way to fix it?
If you have your rba on a mech or you don't have the LCD on your mod to show resistance, you may not have noticed the problem.

For anyone that hasn't seen the v2, here's some pics.

v1 on the left; v2 on the right

 

[State O' Flux]

That looks like a good idea on paper, and a bad one in practice. I take it the contact pin is permanently swagged into the center pin?
I have two on order... if I have the same issues (and assuming I can't find a few V1 center/contact pin sets) I'll grind the swage that (apparently) retains the contact pin off, tap the center pin with threads, and fit a screw and o-ring(s) to emulate the V1 style.

 

[carrielsal]

I haven't found a way to disassemble the 2 pins. This is where I suspect the issue lies.

 

[State O' Flux]

I haven't found a way to disassemble the 2 pins. This is where I suspect the issue lies.

Judging only from the photos... the "ring" surrounding the 510 contact pin on the center pin is what's called a "swage", where the metal is pressed inward to secure the contact pin.
You'd have to take, preferably a dremel or die grinder, or a file if you don't have those... and remove enough of the swage to release the contact pin and spring.

 

[MikeE3]

carrielsal, nice you opened a thread on this over here.


Yes, the spring connection in the 510 pin is wonky - depending on how far or not it is pressed in the Ω reading is different. Here's a post I made in another forum about it, that has brought it to light. Since I posted this yesterday, 7 more peeps have come forward and said they have the same problem w/ the Version 2 R91. Not good.

Ok - After putzing w/ one of my new version 2 R91's for an hour+ last night and another hour+ today - I'm calling it 'flakey' due to the new spring loaded 510 pin.

Using a DVM I get .6 Ωs between the +/- screws for my coil. I get .6 Ωs from the + screw to the top of the deck, I get .6 Ωs from the + screw to the 510 threads.

But .....

I get 1.7 to 2.7Ωs from the spring loaded post to the 510 threads (reading just keeps floating around on the DVM). Push the post in to about where it would be when threaded to a PV it then reads about 1.5-1.7Ωs "if" I put some side pressure on the post - if not the reading floats around like when the pin is full extended.

If I bottom out the floating pin - the reading seems to be stable at .8-.9Ωs

If I try to test it w/ one of those little black box Ωs checkers - it reads between 4 and 5 ohms.

My best guess is that my .6Ω coil may be firing at around 1.5Ωs based on checking it w/ a meter w/ the pin pushed in about what it would be when screwed to my PV.

My other Ver 2 R91 does not have this quirky behavior - whatever points I use to read the ohms - I'm getting 1Ω as I'd expect for that build.​

 

[crxess]

Hate to see this in a higher end device. Same problem that plagues cheaper spring loaded clearomizers.
With that exception the Russian seems to be an excellent well built device.

Just seems like a step backward. Hopefully if more have the issue, they will supply a corrected replacement part.

 

[State O' Flux]

Interesting information Mike...

Sounds like the spring for the 510 pin isn't very effective at consistent continuity. It's really too bad you can't take it apart without permanently destroying the swage. They could have threaded it, and put a stiff spring in there as well to prevent the 510 pin from turning too easily.

I wonder what the resistance values are, if the 510 pin is completely bottomed out against the center pin shoulder. My thought is that as a test, one could wrap some thick wire, say 22 or 24 gauge Kanthal, around the pin to space it at the desired length (to obtain good continuity at the PV), and everything would be firmly bottomed out, to get a good continuity value for the atty as well.

Just tossing spit balls until mine arrive. ;-)

 

[MikeE3]

Interesting information Mike...

Sounds like the spring for the 510 pin isn't very effective at consistent continuity. It's really too bad you can't take it apart without permanently destroying the swage. They could have threaded it, and put a stiff spring in there as well to prevent the 510 pin from turning too easily.

I wonder what the resistance values are, if the 510 pin is completely bottomed out against the center pin shoulder. My thought is that as a test, one could wrap some thick wire, say 22 or 24 gauge Kanthal, around the pin to space it at the desired length (to obtain good continuity at the PV), and everything would be firmly bottomed out, to get a good continuity value for the atty as well.

Just tossing spit balls until mine arrive. ;-)

I kind of did something like your proposed test. With the moveable pin full extended I get a 2.5+Ω reading, when it's fully compressed I got .8Ω for a coil measuring .6Ω between the +/- screws connecting the coil.

It may also have something to do with the size/diameter of the moveable pin itself. On the wonky one it 'seems like' there's more wobble and the the 'good one' is a tighter fit. The 'wonky' one seems to act like a cheap mech mod switch that you have to mash to the side of the tube to make good contact for it to fire. The 'wonky' one can change it's ohms just by pushing it off center w/ the probe when doing an Ω check.

 

[State O' Flux]

I see a Kebo/UCT recall... coming soon.

They should have got it right the first time.

Oh well... arm chair QB on a Monday afternoon. Time for a nap. ;-)

 

[carrielsal]

Mike - My resistance changes without touching anything.

 

[MikeE3]

Mike - My resistance changes without touching anything.

Yeah - I've seen that too when holding the test probes to it - the meter just fluctuates up/down/up/down and all around. Does that when screwed into the black box ohm checker too. If I wait long enough - it might eventually settle down.

 

[jackmormon]

carrie-

Have you tried to see if the V1 pin will fit into the V2? I would try it but am traveling this week Very curious as this is a huge flaw if consistent across units.

 

[HazMatt]

Not what I want to hear. I ordered my first Kayfun style atty, which happens to be a R91 v2. It should be in the mailbox waiting on me when i get off of work tonight.

 

[carrielsal]

carrie-

Have you tried to see if the V1 pin will fit into the V2? I would try it but am traveling this week Very curious as this is a huge flaw if consistent across units.

Not yet, but I don't know why they wouldn't be.

 

[carrielsal]

Not what I want to hear. I ordered my first Kayfun style atty, which happens to be a R91 v2. It should be in the mailbox waiting on me when i get off of work tonight.

Let us know if you have this problem with yours.

 

[HazMatt]

Let us know if you have this problem with yours.

considering I am about to wrap up a 16 hour shift, I may not get around to cleaning and building it until ttomorrow night. But, I will report what I find.

 

[Telekinesis]

I was wondering if I was the only one having issues with the new v2. I've been searching for the last few days trying to find something. Not good. Readings are all over the place.

 

[HazMatt]

Yep, same (expletive delete) problems. Since I had a pre-wrapped coil in my tackle, make that vapor box, I decided to install it in the R91 v2 that arrived today.

First, I try to loosen the positive terminal only to discover that apparently, I must finish ASSembling this piece of (expletive delete) atty. Since I just got home from a 16 hour work shift, I am not quite coordinated enough to hold and manipulate pliers, the atty, and the spanner wrench all at the same (expletive delete) time.

I manage to get the coil securely installed and screw it into my ohm meter. .... 2.92-3.99-1.63-4.21 The readings are all over the place. I tighten the base as tightly as I dare onto the meter. 2.21-2.19-2.11 at least it stabilized some. I screw it onto my Vamo. Ohms are still bouncing. Now between 1.6 and 2.2 ohms. Heh, 2.2, appropriate for the piece of (expletive delete).

I finally decided to try out a Kayfun style atty. Do I buy a EHPro or Tobeco clone? NO. For the first time in 11 months of vaping, I decided to step out of my "$50 or less" comfort zone. I think, why not get a quality device. And then, a few days later, this (expletive delete) (expletive delete) (expletive delete) (expletive delete) arrived.


Fuuuuuuuuuuuuuuuuuudge.

 

[MikeE3]

I was wondering if I was the only one having issues with the new v2. I've been searching for the last few days trying to find something. Not good. Readings are all over the place.

Yep, same (expletive delete) problems.

Fuuuuuuuuuuuuuuuuuudge.

Welcome to the club gentleman.

A couple-few things;

Make sure you have the 510 pin screwed in good and snug using that little spanner wrench, actually as tight as you can make it. It may help but honestly I'm doubtful. Even on a V1 if that connection is loose there can be issues.

We've identified a low cost rebuilt kit w/ the V1 2x screw 510 post. Some us have already ordered and should have them for testing in a couple-few days.

If you bought it retail from a vendor - perhaps you can exchange it. I have 2x V2's and only 1 has the problem.

 

[MikeE3]

hmmm - someone just sent me this link to another forum mentioning a problem w/ the floating pin and seemed to indicate the manufacture is coming out w/ a fix.

XXXX://YYY.ar15.com/forums/t_1_175/1609086_Russian_91__V2.html

change XXXX to http
change YYY to WWW
and have a look see.