MFU issues

[ararmen]

I finally have the MFU installed in my Merc. It's a really tight fit as all the components are in the cab including the interior. On first try the unit worked OK. Then, on its own and for some strange reason the turn signals reversed, left to right and right to left? Took out the MFU and reset it, no luck. Finally on the third try, it reset and starting blinking in the correct direction. Now, when the truck is backed up, and turned left or right the turn signals do not work, only the reverse tail lamps. Having read the instruction, I tried the timing adjustment switch which adjust the signals but it did not cure the problem! The MFU has a mind of it's own. I like the sound and the vibration but the lights are a problem. Any suggestions on correcting are appreciated.

[Larrio]

You can call our Customer Service department for technical assistance in the U.S.
800-826-4922

[ararmen]

Hello: Thank you very much, will do.

[Larrio]

Let us know if your issues are resolved. You can email or message me here on the forums.

[ararmen]

I received more information from Tamiya USA tech support. The turn signals are not supposed to work in reverse, but they are supposed to work in all forward gears. So I still need to sort mine out. As far as the truck shutting down while running, this was my battery problem, used a third new battery and the truck ran fine.

[calm n sedated]

Technical service is worthless, this mfu has a mind of it's own and they have no idea what to do about it. I have this issue and many more on one of my muliti function units. Just reverse the plugs until it decides to revert on it's own. If you have a trailer you will need to transpose the right and left wires on the output connection at the 7 pin terminal (or however many pins there are). If ya don't your truck will signal correctly and the trailer will be opposite. By the way, another mfu malfunction that is common is the vehicle direction, it will all of a sudden start going backward and beeping when you press forward on your controller. If resting the mfu doesn't work just change the polarity of the wires at the motor.

[Gomjaba]

This is no ranting as I don't have an MFU yet (still struggle to decide) but when I did some research (tried to find the manual online) I found the same issues on several forums, such as RCUniverse etc.

A lot of people seem to have similar issues and about 20% have to change the polarity as you mentioned ... I don't think the problems won't keep me from buyin it but this is something whch seems to be very common ...

[calm n sedated]

The mfu does have its problems and idiosyncrasies but it is the best sound unit for the price. You can get better electronics like servonaut but they will cost more and sometimes have issues with the U.S. transmitters.

[Larrio]

When you say "reverse the plugs", aren't you reversing the polarity? I would think that'd be a huge no-no for electronics.

[shodog]

Technical service is worthless, this mfu has a mind of it's own .

I have set up three mfu's and never had a problem with any of them. Sounds to me like either your radio's are not zeroed out or your hooking up lights incorrectly.

[calm n sedated]

This is a well know issue, many other people using the tamiya semi mfu have noted these exact problems. I have seen this issue on several other boards. Wiring close to a dozen of these things, I have had two mfu's that have had problems. Most are able to cure the problem by reseting the unit. Radios are always set to center before programming, I have also used multiple radios with the same result.

Lario, the polarity is only reversed on the motor, not an issue; the turn signals are only switched. Right for left, left for right ect. Just placing the right turn signal where the left should be on the board. For the trailer...same thing just transpose the right and left wires on the 7 pin harness. These are LED's even if you switch polarity it won't hurt them, they are diodes (one way device)

[Larrio]

Ah, I see. That makes more sense now.

I'll ask about the MFU issue with the customer service department.

[CarKing]

Technical service is worthless, this mfu has a mind of it's own and they have no idea what to do about it. I have this issue and many more on one of my muliti function units. Just reverse the plugs until it decides to revert on it's own. If you have a trailer you will need to transpose the right and left wires on the output connection at the 7 pin terminal (or however many pins there are). If ya don't your truck will signal correctly and the trailer will be opposite. By the way, another mfu malfunction that is common is the vehicle direction, it will all of a sudden start going backward and beeping when you press forward on your controller. If resting the mfu doesn't work just change the polarity of the wires at the motor.
Well I can't say that I agree with the worthless part of your post....

I also would like to go on record as saying reversing the polarity is not in anyway recommended by Tamiya. We have had many MFUs come through our department and 99% of them were installed incorrectly. We have heard the instructions are difficult to follow at times, but most people who call have issues with wiring and not a faulty unit. Someone just sent some in to be checked claiming the same flaw you discussed and they worked 100% fine on our rig.

If at any time you feel your MFU does not work correctly, please call us and we can walk you through the problem. Worst case scenario, we do offer a repair service if you chose to do so if we cannot solve your problem over the phone.

[calm n sedated]

Carking:

How would reversing the polarity on a multi directional brushed motor cause problems?

If it were wired incorrectly then how did the unit fuction properly for almost 3 months? Then out of the blue, with no changes the turn signals started to function in an opposite fasion. Now the truck went to turn right and the left turn signal started to flash.

[mcovalsk]

I would like to give my 2 cts opinion as electronic engineer. :first: I don't have a MFU still (I'm waiting mine) but I have built few RC 1/16 tanks, Pershing and Sherman with DMD and MFM. We have to be in account that the microprocessor (CPU) is receiving a digital signal, the width of the pulses is a must here, so if your radio transmitter have a wrong setting OR hasn't the right pulse train conditions ( I have seen this many times repairing RC and looking the pulse train in an oscilloscope), then the CPU could understand something different what one suppose should be.
Of course some MFU could have a malfunction that the technical service should fix or replace the unit, but I think most of the problems are about the transmitter setting. But if you make the MFU setup with a faulty radio or incorrect zero adjusted...or something, then the CPU will give unexpected functions, I have seen this with the Pershing and fixed the problem just making a little adjust to the internal preset of the 4 channel transmitter. Also a bad transmitter battery or a faulty voltage regulator or even some capacitor could give a bad function, that will not affect servos because they only will work in a different angle relating to other transmitter.
:Good Point:The point is that each channel was converted to 3 channels using the low and upper limits of the pulse width, if the transmitter fails to send the right information that match the window of work, then the CPU will not understand what to do and will decide something wrong. Probably this is the reason that only few transmitters are recommended.
Sorry for my English here, ages since my last technical text in English. :LOL: :sorry:

[CarKing]

We see a lot of these issues turn out to be radio issues rather than MFU issues. I cannot comment on why your system would loose its settings out of the blue, but the other tech is definately the guy who knows about these systems and you can call and talk with him anytime.

I am not saying that it will hurt the system, and I am not saying it won't hurt the system. All I am saying is that for liability and warranty issues, Tamiya does not recommend changing the polarity on the unit. If this has proven to work for you then I am glad to hear it! It is just not a solution that Tamiya will endorse. Since we have not experienced the loosing settings issue with our units, we have not tinkered with changing polarity at all. Feel free to send yours in and we can take a look at it.

[chiefsquattingmonkey]

i had problems with my mfu on my high lift and they were almost the same symptoms. i found out that back in the day (80's) people found that antenna wire touching other wires (including itself) would cause interference. i unrolled my antenna wire and ran it along the bed of the truck and, problem solved. truck runs fine.