Help! Invert Mini problem

[rawbutter]

A friend gave me his old Invert Mini to fix because I "know more than he does" about paintball. Trouble is, it's an electronic gun, and I don't have a very good track record with fixing electronics. Pretty sure I'm 0-3 at this point.

Anyway, the problem is kinda like first shot drop off, except in this case, the first trigger pull does nothing. Neither does the second, usually. But after five or ten trigger pulls, the marker shoots. Once it's going, it works fine. No leaks. No drop off. Good consistency and fps. If I stop for a few seconds or even a few minutes and shoot again, it's fine. But if I put it down for an hour and come back to it, it will have trouble getting going again. Pulling the trigger does absolutely nothing the first few times. Then suddenly it will fire and all it well.

I'm using a fresh 9v battery, of course, and plenty of pressure in the tank, which has a standard 850 psi output reg. The marker is on the older side, obviously. I'm pretty sure it's been sitting in his basement for at least 5 years. He's only just starting to come out to play again after a long hiatus. I guess the o-rings could be going bad, but it's not leaking, so I haven't taken it apart yet to look.

Any idea where I should start?

[Shaftski]

solenoid sticking is my guess

[jokers]

So I hate to be the bearer of bad news but that is a pretty common thing to happen to mini's. You can try and change the solenoid and sometimes that works, but I have swapped solenoids, eye boards and I think other parts that were not directly related ie bolt, poppet valve, and other internals and it continued on. I think that it is the capacitor on the main board is going bad and the main board needs to be replaced, or the capacitor on the board needs replaced. I have a couple of minis and what i typically do before i take the marker out to play is shoot at chrono to get it going and then as soon as i get out on the field i shoot a couple of times to make sure the marker is working rinse and repeat every time i go out again.

[jokers]

Now if you decide to live with missing the first couple shots, a couple things to keep in mind. I have not experienced it getting worse, my marker sticks when i power it on and after a couple of hours of being powered off but never during a game. If it is freshly from the basement i would suggest changing the o-rings out ZDSPB has an excellent break down of the mini and i would highly suggest reading their break down guide. If you can find one I would suggest the Nummech foregrip extender. I have found whether it is dow 33 or something else if i put on grease it is extremely light and "only" on the o-rings (some will get on other things and that wont hurt anything) and depending on the cold oil works better for the marker.
If you decide to change out the capacitor I would be very careful and match the cap exactly not just close. The markings on it are "REC 2200 microfarad capacitor 10v 105 Celsius LZ 0801" the micorfarad is the symbol and the Celsius is C degree sign. If you need help feel free to reach out to me here or via DM and i will do what i can to help.
This one I am very unsure of but I will do my best here.
REC = Maker
2200 uF = 2200 Microfarad capacitor
10V = this capacitor must be 10 volt rated
105 C = max operating temp of the capacitor
LZ = Series
0801 = Date made
It is a Aluminum Electrolytic Capacitors and has a very low impedance. CapXon is the overall manufacture even though REC took credit at the time

[rawbutter]

This info is awesome. Thank you!

[Axel]

Solenoid stick was a common problem with Minis and yours doesn't sound too bad. Eventually they can several dozen trigger pulls to get started, or stop working entirely. You can rapidly dry fire the gun without air (hold down the trigger when you turn on the board to start it with the eyes off) until the solenoid starts clicking, just to get it going.

Empire would also recommend disassembling the solenoid and carefully cleaning the piston. In my experience, this did nothing, but if you try, be careful not to strip the housing screws, they are made of butter-grade steel.

Replacing the solenoid fixed it for me, at least until the replacement starts going bad, too. This is the weakness of the design. At least they are on the cheaper end of paintball solenoids.

[rawbutter]

Thanks so much for all the help, guys. I've changed capacitors before, so that's not completely out of the question, but I think I'll try a new solenoid first and go from there. I know the new one will also go bad sooner than later, but the owner of this gun plays so infrequently that I'm sure it will still last him a very long time.

[Shaftski]

those solenoids don't like being stored unused. kinda like a racecar, the longer it sits the worse it performs.

every now and then the marker should be taken out, powered up, disable eyes, and dry fire it a bunch. i do this about every few weeks with mine and it's never gotten stuck. gotta move the piston around.

[jokers]

Before you replace the solenoid you might try to rebuild it and save the 40 dollars for that noid. The previous link to the break down guide on ZDSPB has how to tear it apart and rebuild it.

[rawbutter]

Before you replace the solenoid you might try to rebuild it and save the 40 dollars for that noid. The previous link to the break down guide on ZDSPB has how to tear it apart and rebuild it.

I took your advice and tried to rebuild the solenoid, but as I was doing that, I noticed that the cup seal that's inside the plunger (kinda reminds me of a regulator seat) was starting to crumble. Pieces were flaking off. When I put it back together, that seal gave out and the Mini started leaking like crazy. So I'm going to replace the solenoids.


One other question while I've got this thread going, though. Is there any way to make the Minis softer on paint? When I was test shooting these guns in my backyard, I noticed that they have quite a bit of kick. It's not as bad as a Tippmann or Spyder, but it's definitely worse than most other electric guns I've shot. Worse than my Automag, for sure. Is that normal?

Also, they were breaking paint more often than I would like. I was shooting the same paint (Valken Graffiti) that I used at a game day two weeks ago. This same paint didn't break once in my Automag all day (which is certainly harder on paint than most newer guns), but I got 3 barrel breaks in three different pods I shot through the Minis, even after cleaning the barrel between pods.

The Mini ASA/regulators are set to 200 psi like the manual says. They're shooting at 290ish. So, can I do something like decrease regulator output pressure and increase the rear velocity adjuster? Will that make each shot have more volume at less pressure? Or do I need to fiddle with board settings? Like I've said, I don't have a whole lot of experience with electronic guns. I know how to change the settings, but I don't know what all those settings do.

[jokers]

So I am going to give you a compressed easy answer and a little bit of "homework" if you want to do it. First off the piece that you describe as crumbling is likely the poppet valve (went with ANS because I am lazy), there is only a single solenoid.
As to your second question about the mini being soft on paint to get it as soft as possible I would tune it in which requires a good amount of paint, air, and a chrono, as well as think about a new bolt there are apx 3 bolts out there right now Techt, Exalt, and Boss maybe more but those are the ones I have used. The delrin techt seemed to work the best for my mini, the boss worked best for my axe 2.0 and ax pro.
There is a write up on tuning for the mini over at pbnation that goes in depth and will go through dwell sweet spotting the marker and other items but I am going to give you the nickel tour.
Take you marker and set the regulator output pressure to 120 psi. I recommend removing the velocity adjust and then screwing it in till it has 4 turns, raise the velocity from there (likely 2.5 turns). Every adjustment of the velocity adjust means min 5 balls through the marker. You will find a spot that the velocity starts to become inconsistent +/- 25 fps or there is a leak from the back when you find that decrease the velocity a little check with 20 balls for consistent fps (likely a lot lower than 280 fps) when the marker is shooting consistently raise the regulator pressure to get the fps that your field requires and use the regulator to adjust velocity from there. I will guess the pressure will be 160-180 psi. If you have the marker apart I would recommend polishing the poppet valve and during the winter use oil.
The PBnation write up by ironyusa goes into more depth of how to sweet spot and tune they go into dwell and other items but this will give you a good starting point.

[rawbutter]

The piece that you describe as crumbling is likely the poppet valve (went with ANS because I am lazy), there is only a single solenoid.

No, it's the solenoid. Sorry I didn't describe it well enough. I don't know the name of the parts. Inside the solenoid, there's a smaller armature that moves up and down depending on whether the solenoid is charged or not. The tip of that armature has a round brass feature with a cup seal inside. That's the seal that's falling apart.




Thanks for all that help about tuning the Mini, though. That's super helpful. I'm not looking to get it all maxed out and working the best possible way. I'm just trying to make it a little softer on paint so it doesn't break balls in the barrel so easily. I've got plenty of paint and air, luckily, so I'll try out your way first, and if that doesn't work I can always look at the PBnation page. Thanks!

[rawbutter]

Update:

Changing the o-rings and the solenoids fixed both Minis. I'm a happy camper now. Surprisingly, most of the buna o-rings inside the guns looked and felt okay, despite sitting for at least five years. It was only the polyurethane o-rings on the poppet that had totally turned to gum. I replaced all the o-rings anyway.

Well, all the o-rings except the regulator o-rings. I don't have the tools needed to take that apart. But I figured that since the rest of the o-rings seemed okay, the ones inside the regulator will probably be okay for a while longer.

I also adjusted the velocity and regulator. Both guns ended up with the velocity adjuster just about flush with the back cap and the regulator at 180-190. Doesn't seem like a big change, but they were now both able to shoot through a few pods without breaking a single ball.

I'm planning to play again on December 10. We'll see how they hold up.

[rawbutter]

New problem. I took the Minis out last weekend, but neither one of them saw field time. When I aired them up, they both did a weird farting thing. They would cycle and move the bolt, but they would only shoot the paintballs about 5 feet. So I gave up pretty quick on them and switched to Emeks.

Once I got the Minis home and tested some more, however, I realized that they would start working...after a while. Here's a video of what I'm talking about. This Mini has been sitting in my garage for a few days. When I add air and a battery, it doesn't shoot right at first. But then about a few dozen shots everything starts to get going again, and it will keep working fine until I let it sit for a few more days.

Remember, this Mini has brand new o-rings and a new solenoid. Good battery too.

Is this normal with a new solenoid? Is there a break-in period or something?

[Jordan]

^^^^

Sounds like a sticky poppet... mine used to do that all the time. I ended up switching to oil instead of grease in that area.

[rawbutter]

Thanks for the info. I'll try that.

[scottieb]

I don't think it's a break in period. I've heard this is common. Now, how to fix it? Hopefully someone will chime in so you can get an answer.

[rawbutter]

^^^^

Sounds like a sticky poppet... mine used to do that all the time. I ended up switching to oil instead of grease in that area.

So, I took apart the bolts again, wiped off all the grease, used some oil, and tried them again after letting them sit for a day. Same problem.

Then I got to thinking about the o-ring itself that's on the poppet. When I rebuilt the Minis, I bought some generic o-ring kits from eBay that had all buna o-rings, which is mostly okay since most of the Mini o-rings are indeed buna, but the one around the poppet is not. It's polyurethane. So, on a whim I bought some of these original spec o-rings and installed them on the Mini poppets instead, and boom, problem solved. No more sticky poppets.

Lesson learned, I guess. Buna o-rings are okay for everything but the Mini poppets. Use polyurethane for that.

[Jordan]

Yep... didn't realize you had buna on the poppet. Definitely a "must use PU" area.