Help! Rig won't run!

[eightball]

Hey everyone! I just completed building my first kit. I built the King Hauler and I added on the MFU. The sound effect for the truck starting up goes when the switch is turned on, but then it beeps and shuts off and does it again. It keeps repeating itself. The lights do come on, but I can't get it to do anything else. Also, I can't get the steering, throttle, or shift to work. I am using an Airtronics Vanguard Transmitter (6 ch, but only using 4).
Any thoughts as to what I am doing wrong? Is the radio just not compatable with the MFU?
I couldn't find the radio that Tamiya suggests to use for the MFU. I need some help, please. One last question. If the receiver battery pack is not used, how is power getting to the receiver from the truck battery pack?

Thanks:Tamiya1:

[shodog]

check the swtiches on your control module and make sure they are properly set. Seee how I have mine set in this picture

http://www.tamiyaclub.com/tc_userimages/34/img34_16102004205618_2.jpg

If it keep starting and shutting down then most likely your battery is dead and needs a charge.

[janderson]

If it keep starting and shutting down then most likely your battery is dead and needs a charge.

Shodog is right sounds like a battery issue. The vangaurd should work the only limitations on the MFU are

4ch
analog trim

There will be some tinkering to get it all set right if you do not use the futaba attack.

Make sure you go through the setup procedure on the MFU

[McFig]

One last question. If the receiver battery pack is not used, how is power getting to the receiver from the truck battery pack?
Thanks:Tamiya1:
The MFU is your receiver and ESC all in one.

[Mouton]

McFig, that is not true at all. The MFU is a control unit but it cannot receive radio signals and recode them to impulses for various channels. For that you need a separate receiver on the corresponding frequency as your transmitter.

eightball, how old is your radio system? Airtronics/Sanwa did not jump the Futaba connector standard bandwagon until the year 2000. If your receiver is older than 2000 it means the servo leads are pinned differently in the plugs. This will cause problem and may even cause damage. All Airtronics/Sanwa receiver that feature the industry standard pinned plugs have blue receiver cases.

If you have a pre-2000 Airtronics/Sanwa receiver you must rearrange the pins on all the four servo cables going to it from the MFU. This is very easy to do and you will find all the help you need in step 1 on page 2 in this (http://teamnovak.com/download/instructions/pdfs/GTX_ins.pdf) ESC manual from Team Novak. What you need to to is to rearrange the pins (that will look like in Figure 1 so that the look like in Figure 2. You may also need to cut the tab on the side of the connector housing. I would recommend servo extension cables for this modification and that you change the connectors on the extension cables. That way your MFU is kept intact, in case you later on upgrade to a more modern radio or use another receiver.

If you have a pre-2000 receiver, this should do the trick. If it still does not work read the remainder of the post for other possible explanations to your problems.

Shodog and janderson are correct, the behaviour you describe will occur when the battery needs a charge. But, when you loose contact between the transmitter and the truck the same thing will happen. It might very well be that your radio system is not OK or that it is not correctly connected. The receiver gets its power via the MFU. All servo cables have three leads, plus, minus and signal. This normally means that the plus and minus cables supply power to the connected servo and the signal tells it where to move. When you use a ESC (electronic speed controller) it already has a power supply, the main 7,2 V battery. Since the throttle channel already has its own power supply, those plus and minus leads are directed in reverse - going to the receiver. This is called BEC and the built-in ESC of the MFU has this feature. The MFU thus powers the receiver. BEC also means that it transform you main battery's 7.2 V to 4.8-6 V, which is what receivers operate on (7,2 V can fry a non-BEC receiver).

Some, mainly older receivers, cannot take incoming power on their outgoing terminals. My JR receiver from the early 1980s does not have BEC printed on it. I opened it up and noticed that the plus and minus terminals on the circuit board were all (channels and battery input) connected in parallel. I tried it (at my own risk) and it works.

If your receiver cannot accept incoming power you would still need a separate receiver battery pack. When you do that you also need to disconnect the plus lead on the throttle channel going from the MFU to your receiver or you may fry your receiver. Get an extension cable and cut the plus lead on that so your MFU remains 100 % intact.

What you should do is to make sure your radio gear works properly. You would best to that by disconnecting the MFU entirely. Hook up one servos directly to your receiver and use a separate receiver battery pack. Check that the channel in question responds normally to transmitter input. Do the same for all channels. All channels should work - if not it means one of three things:
1. The servo is broken. Simply use another servo then.
2. Defect crystals.
3. A problem with either your transmitter or your receiver.

When you know the radio gear works you could test for BEC capability. If your receiver cannot run on the power supplied from the MFU the result is the same as a turned off transmitter, no signal going to the MFU, which thus keeps turning itself off. Disconnect one motor cable (or place the drive wheels in the air). Then connect the throttle channel from the MFU to the receiver and power up the system (with no receiver battery pack). One channel on your transmitter should now be able to control the motor. If it does not

Here is a tip, the MFU appears to have a built in fail safe that stops all activity when there is no incoming signal. I use this feature to remotely start my rig. I start my rig by turning on the truck and then turn on the transmitter. This requires the Select Sw. on the MFU to be set to its middle position.

Hope this helps!
Andreas

[eightball]

Wow guys! Thanks to everybody for your help. I will try everything that you guys suggest and see what happens. The battery for the truck had a fresh charge on it (off the charger the same day) when I hooked it up. But I will give it a shot and see what happens. FYI the radio is dated 1994. I may be spittin up a rainpipe with this radio, but we'll see what happens. Thanks again for everyone's imput. Let you guys know soon.

[McFig]

You are correct. Not sure what I was thinking that day. Smoking crack again I guess.

[Mouton]

eightball, I see nothing wrong in using an older radio as long as it works allright. I use a radio from ca 1984 myself for my big rig and I know of a couple of other truckers here that also use old radio gear for these models.

[eightball]

I unhooked the MFU and hooked up the battery to the receiver. No signal is getting through. I think I need a new radio. Which ones do you guys use? Which one do you suggest?

Thanks again

[Mouton]

What you are saying is that when you have a receiver battery pack and servos (with the rearranged pin configuration) connected directly to your receiver your radio is dead?

If so, why not check out Futaba 4 EXA, 4VWD or 4YF? Those are among the popular choices.

[Swedspeed]

Check that you got the right crystals in your radio and transmitter. Crystals can go bad. Also check that you got the right crystal in the right place, those markt TX are for transmitters and those markt RX are for receivers. If they sit in the wrong place, the radiosystem may not work. I am using a Hitec Laser 6, got it at a good price and it is easy to modify to get springloaded neutral returns on all four stick inputs. Works good i think.

[eightball]

I picked up the Futuba 4YF. It's working great! I'll be posting up some pics of my build soon. Thanks to everyone for your fantastic help and advise!