My new M41 Bulldog has Gremlins!

[Gottafly]

Hoping someone has a solution before I return or start modifying my brand new M41 Bulldog…
This is my 2nd Heng Long tank, after the Merkava…which I love but has its own gremlins (no smoke, battery drain in storage/off mode, etc). It’s being replaced by MRC, so I ordered the Bulldog to play around w/ while I wait…

The M41 on delivery (today) runs fine but refuses to completely turn off. When the battery is plugged in, the LED lights front & back all light up, even with the switch off. The receiver is running when the battery is plugged in, even though the switch is off. I know that the receiver and lights will cause battery depletion and damage. I know the receiver is being powered because it recognizes whether the TX is powered on (but not unlocked/engaged). The switch on the M41 causes the LEDs to blink slowly when the TX is OFF, but when the TX is powered ON the lights blink more rapidly (before hitting the Start/unlock button)…very strange.

The wiring inside looks fine. The switch looks fine. I’ve even unplugged the switch from the board (7.0) and it still lights up when the battery is plugged in.

I was hoping there was a “hard reset” of sorts for the board, but I can’t seem to find anything. I’d really rather not have to return this one for replacement as well….and may instead put another switch in-line between the battery & the board, but was hoping for something less invasive.

[Max-U52]

My advice is send it back. If you know exactly what the problem is you can sometimes just have them send the parts and fix it yourself, but with what you describe I wouldn't muck about. It should be fully functional when you take it out of the box, and they should pay return shipping. The first two tanks I bought, back in 2012, both had to go back. It sucked, but the replacements functioned flawlessly, so it was worth the wait. I still have one of those two tanks, too. Oddly enough, the one I don't have anymore is an M41, gave it to my nephew when I picked up an Imex M41. (still HL, but with metal tracks and sprockets, something a lot of places offer now).

Here's my M41 right after I got the clark for it. I really like the sounds on this board. Engine start up is cool, and so is the .50 cal track

https://www.youtube.com/watch?v=s-H_hqIVYbQ

And this is a second upper hull I built for it, so I can swap back and forth. I did the light mod before I found out it shouldn't have four lights like that, one on each side is actually an infrared light for that system. Oh well, I still like it with four.

https://www.youtube.com/watch?v=VWtswhQMotQ

[Rubicon99]

Hoping someone has a solution before I return or start modifying my brand new M41 Bulldog…
This is my 2nd Heng Long tank, after the Merkava…which I love but has its own gremlins (no smoke, battery drain in storage/off mode, etc). It’s being replaced by MRC, so I ordered the Bulldog to play around w/ while I wait…

The M41 on delivery (today) runs fine but refuses to completely turn off. When the battery is plugged in, the LED lights front & back all light up, even with the switch off. The receiver is running when the battery is plugged in, even though the switch is off. I know that the receiver and lights will cause battery depletion and damage. I know the receiver is being powered because it recognizes whether the TX is powered on (but not unlocked/engaged). The switch on the M41 causes the LEDs to blink slowly when the TX is OFF, but when the TX is powered ON the lights blink more rapidly (before hitting the Start/unlock button)…very strange.

The wiring inside looks fine. The switch looks fine. I’ve even unplugged the switch from the board (7.0) and it still lights up when the battery is plugged in.

I was hoping there was a “hard reset” of sorts for the board, but I can’t seem to find anything. I’d really rather not have to return this one for replacement as well….and may instead put another switch in-line between the battery & the board, but was hoping for something less invasive.

Now this is something I have not seen or heard of before🥴. I would have them simply send you a new MFU. Takes just a few minutes to install vs the time and effort to send the entire tank back.

[keilau]

Hoping someone has a solution before I return or start modifying my brand new M41 Bulldog…
This is my 2nd Heng Long tank, after the Merkava…which I love but has its own gremlins (no smoke, battery drain in storage/off mode, etc). It’s being replaced by MRC, so I ordered the Bulldog to play around w/ while I wait…

The M41 on delivery (today) runs fine but refuses to completely turn off. When the battery is plugged in, the LED lights front & back all light up, even with the switch off. The receiver is running when the battery is plugged in, even though the switch is off. I know that the receiver and lights will cause battery depletion and damage. I know the receiver is being powered because it recognizes whether the TX is powered on (but not unlocked/engaged). The switch on the M41 causes the LEDs to blink slowly when the TX is OFF, but when the TX is powered ON the lights blink more rapidly (before hitting the Start/unlock button)…very strange.

The wiring inside looks fine. The switch looks fine. I’ve even unplugged the switch from the board (7.0) and it still lights up when the battery is plugged in.

I was hoping there was a “hard reset” of sorts for the board, but I can’t seem to find anything. I’d really rather not have to return this one for replacement as well….and may instead put another switch in-line between the battery & the board, but was hoping for something less invasive.

If the M41 cannot be completely turned off, it means that the MFU is NOT disconnected from the battery. It is a simple mechanical problem. Physically disconnect the battery and see what happens. If the tank turns off, the on-off switch may have a short. Use some circuit spray cleaner on the switch. If it does not help, the switch should be replaced. It is a simple slide switch you can get anywhere.

The Heng Long OEM battery is a very low quality one. Replace it with an Admiral brand LiIO from MotionRC will greatly improve your tank operation.

[SoCalBobS]

The closest thing to a hard reset is Step 28 in the manual: Lock + G + K. Turn off the Tx, hold all three buttons, turn on the TX (takes four hands it sounds like. Wait for the DIDI sound (their word, not mine) then release the buttons. However, your issue sounds like the Rx, not the Tx. You could try a re-bind first: Tx off, tank off, turn on Tx, hold Lock button down and turn on tank. In your case maybe you'd have to have someone plug in the battery to turn on the tank.

And I agree with R99.Try to let the seller have you just return the MFU.

[Gottafly]

If the M41 cannot be completely turned off, it means that the MFU is NOT disconnected from the battery. It is a simple mechanical problem. Physically disconnect the battery and see what happens. If the tank turns off, the on-off switch may have a short. Use some circuit spray cleaner on the switch. If it does not help, the switch should be replaced. It is a simple slide switch you can get anywhere.

The Heng Long OEM battery is a very low quality one. Replace it with an Admiral brand LiIO from MotionRC will greatly improve your tank operation.

The only way to power off the unit is by unplugging the battery. I tried the electrical cleaner but no joy. Even if the switch is bad, I don’t think that would explain the fact that it still lights up (and doesn’t turn off) with the switch unplugged from the MFU. The battery leads go directly into the MFU. The switch is plugged into the MFU, not the battery. I would think that would make the fault in the MFU and not the switch but I could be wrong.

Motion RC was not willing to send me parts to correct the Merkava defects, they said they would only replace the whole unit. I doubt requesting a replacement MFU would be any different this time around.

I also tried Bob’s re-binding recommendation but no luck there either. I think I’m stuck either sending it back or installing a switch between the battery & MFU. I’m leaning towards the switch install…

I’m 2 for 4 with Heng Long. The Merkava & M41 were both defective. I also bough a Leopard for my son and a T72 for his friend. They are both enjoying theirs and I’m stuck sending stuff back. Is this par for the course w/ Heng Long or am I the exception?

Again, I appreciate the feedback received.

[Rubicon99]

The only way to power off the unit is by unplugging the battery. I tried the electrical cleaner but no joy. Even if the switch is bad, I don’t think that would explain the fact that it still lights up (and doesn’t turn off) with the switch unplugged from the MFU. The battery leads go directly into the MFU. The switch is plugged into the MFU, not the battery. I would think that would make the fault in the MFU and not the switch but I could be wrong.

Motion RC was not willing to send me parts to correct the Merkava defects, they said they would only replace the whole unit. I doubt requesting a replacement MFU would be any different this time around.

I also tried Bob’s re-binding recommendation but no luck there either. I think I’m stuck either sending it back or installing a switch between the battery & MFU. I’m leaning towards the switch install…

I’m 2 for 4 with Heng Long. The Merkava & M41 were both defective. I also bough a Leopard for my son and a T72 for his friend. They are both enjoying theirs and I’m stuck sending stuff back. Is this par for the course w/ Heng Long or am I the exception?

Again, I appreciate the feedback received.

Just buy a new 7.0 MFU and save yourself time and effort.

[Max-U52]

If you knew exactly what the problem was I would agree with trying to fix it. But you don't. And don't forget the domino principle. Who knows what else this unknown defect might lead to? Say you put in the switch and everything works fine at first, but after a couple days this unknown defect causes something else to overload and fry. Then what? Now you've modified the tank and you CAN'T send it back. You paid good money for a tank that's supposed to perform in a certain fashion. Don't Settle. Send it back and get what you paid for. I don't know if Motion RC is one of them, but a lot of places will even send you a UPS call tag to cover return shipping. You should ask about that. I know you don't want to wait, I know it sucks, but sometimes you just have to bite the bullet. In the end, you'll have what you paid for, without all the stress you're dealing with now.

[keilau]

You only need an ohm meter to determine whether the on-off switch is working or not. Once you eliminate the switch as the problem source, you can decide what to do next. Asking a replacement MFU to test it out yourself? Or returning the whole M41 for replacement? Act fast before the warranty expires.

[cmdrcody]

The only way to power off the unit is by unplugging the battery. I tried the electrical cleaner but no joy. Even if the switch is bad, I don’t think that would explain the fact that it still lights up (and doesn’t turn off) with the switch unplugged from the MFU. The battery leads go directly into the MFU. The switch is plugged into the MFU, not the battery. I would think that would make the fault in the MFU and not the switch but I could be wrong.

I agree if you have unplugged the power switch from the MFU and the power stays on - the MFU is defective. Email "Ozzy" at MotionRC (support@motionrc.com) or call and ask for him (224) 633-9090) and explain the issue with him. He has taken very good care of me in the past if there was an issue with a newly purchased/delivered RTR tank. Just follow his instructions and you should be satisfied. Please note that MotionRC does not take every tank they have shipped in out of the box to test them for their functions, so when you receive it, last person to touch the tank was the manufacturer in China when they put it in the box.

[Gottafly]

I ended up putting an in-line on/off switch between the battery connection and the MFU. It was pretty simple as the stock battery harness had bullet connectors in between it and the MFU. I just soldered bullet connectors onto a new switch and put it on the positive lead. That way the new switch cuts off all power to the MFU so there is no chance of draining etc. Plus I was able to mount it in the stock position under the hatch on top.

The original switch worked/tested fine, so the issue was definitely in the MFU. Other than the power issue it runs great and was much, much easier than sending it back.

I also looked into a new MFU. MotionRC sells the 7.0 for $55. Hard to justify going the replacement route for a $200 tank. I also discovered that Toucan RC has substantially lower prices across the board on almost everything tank related…if you can put up with the horrendous website. I find it very confusing (beyond the language barrier). Do they modify these things with paint, hop-ups, 360deg turrets, FPV etc. and sell them as upgrades, or do they come from Heng Long this way?

Now off to tighten up the veeery loose tracks & add some weathering/airbrushing/detailing.

Thanks again for all the input!

[SoCalBobS]

Regarding Toucan, if you email them directly with what you want, they're very helpful. They take Paypal. If you request an item from US stock, they'll try to do that. Cheaper to buy the MFU than to ship a whole tank back to MRC.

[keilau]

You can get a TK7.0 MFU replacement from a US seller on ebay.

https://www.ebay.com/itm/235249438592?itmmeta=01HT5F69EMXSMCABA1CNCN3B2X&hash=item36c5f58f80:g:abAAAOSwDMFlJfqd