Hi everyone. So I pickup a VStank King Tiger and recieved it yesterday. This is one beautiful tank. The detail is incredible right out of the box. I just wished it worked properly...lol. I put this in one of my other threads but thought I would repost on its own to se if you guys can help me out.

The right side tracks do NOT move forward. Backward works fine. I opened it up hoping to find a connector loose. Everything looked perfect. I then decided to swap the left and right side plugs to see if I could get the motor to run forward. It works perfectly. My assumption is that there may be somethign wrong with the control board which is not allowing the forward command to make it to the right motor plug. I see some trimmers in there but Im not sure what they are for. Could it be something simple like a trimmer that controls the signal to the motors which may be misadjusted? Does anyone know what those trimmers are for? Or...am I looking at needing a whole new board? If a new board is needed, Im shipping it back becasue its not worth going through the trouble. Any guidance you guys can provide would be greatly appreciated.

As I mentioned on RCGroups, I have several of the older (2007) VSTanks, & I have opened up & looked at one tank's controller board as well as opened up the push button style controller too, & I'm not sure what you refer to as something which you see & seem to suggest might be trimmer controls you could possibly adjust.

If you could, it might help a lot to post some photos & point out what you believe are these trimmers, because I didn't see anything when looking at my own tank.

It could possibly be the Tx buttons that have bad contact. The push button controller is very oddly done with the style pads used & the contacts on the board. If you or someone you know had another VSTank you could just try using another set of crystals & Tx to quickly diagnose if the Tx was an issue.

Maybe the forward buttons aren't working on the controller properly because the pads aren't contacting the board correctly. Also make sure the plugs are all plugged in fully inside the Tx especially the two large plugs circled.




Below are the odd contact points, the top 3 for forward motion, the bottom 2 for reverse.





~ Craig ~

HI Craig,

Im sorry for not being more clear. I meant inside the tank itself not the transmitter. The transmitter seems to be working perfectly, its the control board inside the tank that Im referring to. Awesome pictures BTW...

Oh, & I thought it was on RCGroups where I had responded before, but it seems you had another thread here on RCU discussing the issue with this tank where I had responded, ooppps.

But since there is an issue going forward, you cannot really know the transmitter is actually working correctly & isn't what is causing the forward issue. If you had 2 VSTanks where you could switch stuff back & forth & do some testing you could probably find out very easily what the issue is, so that's why I still suggest looking inside the Tx to make sure everything is also connected inside there correctly. If something is slightly loose or disconnected in the Tx, it will cause issues too.

I also just want to make sure the gearbox does spin freely & isn't causing the binding in the forward direction too.

So a follow-up question, can you hand spin the gearbox in the forward direction on the side you say won't go forward, by grabbing the sprocket & just turning it?

Both sides should move in both directions freely, with a bit of resistance, & a little bit of gear clicking noise.

I also looked at my controller & receiver boards in the tank itself but still didn't see anything I would consider a trim. So it still helps if you could provide your own photos to show what you think might be these trimmer adjusment on the tank controller you are mentioning.


~ Craig ~

I will try to get some pictures today or tomorrow.

Both gears move freely. There are to motors inside the tank, one for the right side and one for the left. Each motor has a connector which independently connect to ports on the controller board inside the tank. Since I knew the left side moved forward properly, I simply swapped the left for the right and vice versa. I then powered up the tank and transmitter and pushed forward on the joystick. Suddenly, the right motor started working and the left stopped. This at least confirmed that I dont have a bad motor. When I connected everything back like normal, the problem switched back to the right. Troubleshooting in this fashion tells me the that at least the motor isnt frozen or stuck and works properly. It also tells me that the problem must exist on the PCB connector dedicated to the right motor. To me it seems that there is something interfering with the forward command signal getting to the right motor port on the PCB. I will get some pics posted. Thanks again!

In an earlier post from the original thread where you first mentioned your tank, you also mentioned, "it has the push button controller", but now you say, "pushed forward on the joystick"?

This is confusing details. The push button controller has no joystick. So to clear things up, do you have the push button controller, or the joystick style controller?

Also, if the left motor was working normally before, & you hook the right motor to the left port & the motor itself is OK when tested, then it makes sense the motor isn't an issue. But this test doesn't tell you that the Tx is truly working properly or not.

So I'm not saying it isn't a tank PCB problem, because it certainly could be, but if you are having issues with just one side control, it can still be the Tx causing that issue with the way the contacts might be working, or in this case, might not working, or just a loose wire or plug in the Tx.

All you seemed to have ruled out is that both motors spin in both directions, & the gearbox seems to spin freely on both sides in both directions too, & since I haven't read anything you have done exclusively to test the Tx to rule it totally out as having no issues, I'm not sure why you still only want to focus entirely on the tank board as the only possible cause.

In my opinion, to do the full proper trouble shooting, I still suggest strongly that you take the Tx apart & check the internal plugs & connections, as well as that the contact pads are free from having any debris between them & the contact points on the board, & they are properly positioned where they should be. This is actually very easy to do, & at least an inspection might reveal something that is causing your issue. Even if everything inside looks OK too, at least that's one more trouble shooting step which really needed to be done, out of the way.

~ Craig ~

Thats from a VStank ABRAMS that I also have which has the push button controller.  This is the King Tiger with the VTX-10 .

Completely agree with your suggestion Craig. Im going to look at the Tx tonight and I hope that does it. Thanks so much for your responses!

OK, now we're getting somewhere. You know you could try switching the crystal inside the KT tank to the one from your inside your Abrams turret, then try using the push button controller on the KT to see if you get normal forward movement.

I'm also not sure the older push button controller will even work on a newer tank, since the mfu will be newer, & that is of course assuming your Abrams was still working OK using the push button controller.

~ Craig ~

Yes sir...tried that. The push button old controller doesnt work on the newer King. The ABRAMS and the King both have channel #2 crystalls. I have an extra #7 that I havent tried since I ran into this issue. Im going to go pull thsi thing apart now and see how much trouble I can get myself into...lol

Just finished putting the Tx back together. Nothing looked weird or out of place. I still have a feeling it has something to do with the tank onboard electronics. Any forward movement including rotation that requires the right side track to move in a forward direction does not function. I just dont know enough about how R/C works technically to figure out if its the Tx or the Rx but at least I know its not the motor....lol

Im hesitant to pull the tank apart but was able to pull some screenshots from a youtube video. I searched at ToyEast and this board seems to be the Receiver PCB. Is it posisble theres a problem with the receiver and can be adjusted? Does anyone know what these trimmers do?

I would have to agree that the small board with those trim pots looks like it should be the receiver board, though it's very different to the older ones I have in my tanks.

You may never get a response from someone who has actually taken their similar VSTank apart, & who has fooled with those particular pots to see what they affect as far as the operation of it. The only way that might be available to you, is to just get in there & tweak them to see what affect they have on the tank when it operates.

So this is the big question, do you feel comfortable enough to take the tank apart enough & even test & attempt a repair like this, & then reassemble what you've taken apart?

If you are questioning that at all, feeling hesitant you might mess something up even more, then you are probably just better off sending the tank back for a replacement without trying to do anything more.

Otherwise, even if no one can answer exactly what those pots do, if you feel comfortable enough in your abilities to take the tank apart just enough to get access to that board's pots, leaving everything still plugged in & hooked up for testing, then just do it.

If you want to try, just disassemble the tank just enough to be able to get to those pots. You should be able to still have everything plugged in & wired up so you can still turn on the tank & test things as you go. Of course we know using caution not to accidentally short anything since it would have power .

Take a picture of the pots & their settings for reference, or mark them with a marker, & with the tank on, proceed to adjust a pot on the board by about a quarter turn in a direction, then use the Tx & test to see what it affects on the tank. Other than sending the tank back, it seems all you may have that might help you fix the issue is a long process of trial & error with turning & testing those pot settings.

Either way, good luck, & keep us informed, especially helpful for others will be if you do decide to tweak those pots & discover what they do .... make a video too if you can while testing.


~ Craig ~

UPDATE!

So....this mind boggling issue has had me searching for answers for the past few days. I tried to run the tank a few hours ago and as part of my frustration, I was being a little harsher than normal with the Tx. All of a sudden....the right motor kicks in!!!!! It was the Tx just as Craig had suggested. Now, I can recreate the problem which is a huge step.

Im going to open up the Tx again and do more cleaning. One thing I noticed is that these new Tx's use exposed wiper's like what would be inside a potentiometer. Im going to shoot some contact cleaner in there. The joysticks engage a sprocket that in turn engages the wiper. The wiper moves across the contact surface (again exposed) and sends the signal to move. I havent taken apart higher end Tx's but I cant imagine they are anything near as cheaply made. This thing is flimsy and toyish and not touch sensitive at all.Obviously VStank spent much of their capex in creating an incredibly detailed and aesthetically beautiful tank. Anyway....looks like problem solved...for now.

That's great to hear, perseverance has paid off. I'm glad it seems like it might just be some bad contact for the joystick in the Tx causing the movement issue you were having.

If you could still take some nice pictures of what you are doing, showing the problem area, & post them here it will help future members out a lot, especially since my pictures were of the older button style controller while you have the newer joystick style controller.

Hopefully some cleaner will be enough to fix your issues. However, I might still suggest possibly considering even a very careful, but slight bending of the wipers to make sure there is solid contact all the way through the movement too.

~ Craig ~

CORRECTION!

OK guys...Im back! I thought the Tx was the issue but I actually found the real culprit today. While I was running it this morning, I realized the front headlamp was not working. So I decided to go inside the tank again to figure that out. I fixed it and when I was testing it, the right track goes out again....here we go again!! To make a long story short, the connector next to the lamp connector had a false contact. While moving the lamp connector (in<span style="color: rgb(255, 0, 0);"> RED</span>), I grazed the connector next to it with my finger (in <span style="color: rgb(0, 255, 0);">GREEN</span>) and the right front motor came on. Wiggled the cable around and the motor would go on and off. BINGO!!!!! It was a bad contact specifically on the middle black wire of the green connector in the picture.



FINALLY!!!! Now I can get back to enjoying my King Tiger!!!!

Deleted...starting a new thread...sorry!