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timatc

MFC Issues - Battery?

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I have just finished installing the MFC-03 unit into my Cascadia. The truck works well most of the time, however I can force the unit to shutdown if I move the steering very fast in one direction and the other on the controller - the MFC appears to switch off and switch back on again, with the alarm sound / lights blinking momentarily. This can also occur randomly from time to time, but mainly with the steering.

I have km5515ma 6.0V analog servers for steering / shift and a 3000mAh LRP NiMH 7.2v battery that is very new and charged.

Is this normal, or is the battery / servo(s) to blame? Should I get a different battery?

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An update, this issue only seems to occur if the shift / steering function on the transmitter are moved very fast from side to side (i.e. the rc stick on the transmitter unit). Is this normal?

I have a Futaba 4YWD, and there are reports of this unit not playing nicely with the MFC units. Would it be worthwhile switching to a RadioLink R9S or similar with a new reciever?

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Ok, I have purchased a better tx / radio and reciever - what is being reported is low voltage on the reciever side caused by the servos. Is this common with high power / performance servos with Tamiya MFC units? Have seen other posts which suggests that it is.

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i have the same on my on my grand hauler with the mfu -01 and i run a 5000 batt and also basic servos it may be my battery tbh 

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With the MFC-03 you can shut the truck off via the transmitter. I forget the combination, but it involves moving both L/R sticks. I think it is left stick to the right and right stick up. (same time) Will turn truck back on also. You could possibly be triggering this?

You don't really need high power servo's for the semi trucks. To much power drawn to run the servo's could drop BEC of receiver to drop enough that the MFC thinks it has a dead battery and shuts down. A not so good battery could cause this also.

I installed a small glitch buster capacitor in all my trucks. This will buffer the BEC of the receiver to keep power more stable when needed. Acts like a little battery, that stores a little power, so when power drops it will fill in the gap. About $7.00 and just plugs into receiver. (may need a "Y" if no open spots on receiver) You don't need a big one either. It will helps for this issue also.

If changing radio, always reset the MFC to the new radio, by pushing the button and up/down, left/right sticks.

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Thanks Tamiya Fan 1 and everyone. I can confirm that this was the servos. I have bought 2x Carson CS3 (3KG) servos - will this suffice for a truck?

@Tamiya Fan 1 thanks for your advice on the glitch buster - I might look at getting one of these. Do you ever have brownouts with this installed? Any risk of damage / danger to the MFC unit or reciever?

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Hi timtac,

You just need every day servo's for the truck. Nothing strong or high power, so you should be fine.

The glitch buster is safe, even if you went with a big one. But you don't need anything big. I use Futaba one (1800uf I believe) a couple of bucks more than some but that's me. You just plug into RX and it will do it's thing. Will not hurt the MFC or anything else. You won't even know it is there but truck will be more stable when more loads are put on it. It keeps the RX (BEC) at a stable/constant power. It won't do anything till power drops a little and then even it out. Your RX will not loose signal as easy.

Example: When you are driving and electronics cut out, but still works, just NOT like it should. A "Glitch Buster" could help.

If you have a 4 channel radio, you might need to get a "Y" connector for servo's. So you can plug one of the MFC plugs into "Y" and the capacitor into the other. I think a Carson  radio is a 6 channel, so you should have an open slot on the RX. If 4 channels and a BATT. slot (5 plug-ins) just plug in in the battery slot on RX.

I made it sound complicated, but it is plug it in and forget about it. (MFC SAFE)

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Thanks @Tamiya Fan 1. I've installed 2x 2400uF ones - one made somewhat of a difference, however I was still getting brownouts, with 2x, they now seldom occur (luckily, my reciever is an 8 channel one, so had enough connectors). I am thinking however I might get 1x of say >4800uF to save having to have 2x.

Cheers,

Tim.

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Glad it worked. MFC's are really sensitive to low power cut outs. (built in low battery circuit, so you won't have a run away) You must have something pulling power to need 2 of them and still having brown outs. Are you still running the 6 volt servo's? I think the MFC has a BEC power for RX of only 5 volts (4.8 volts), which could be creating the "brown outs" with the 6 volt servo's. Is 6V. the minimum volt on the servo's or is it listed as 4.8V - 6V on the servo's? MFC are from the older days before higher tech items. You would have 2 items pulling more power than the MFC puts out, causing RX signal to fade out. The capacitors are filling the gap, but probably won't be enough to get rid of if high power servo's being used. You might want to look that direction. 

I've only used big capacitor's for drag cars where the motor is sucking so much power you will loose control power.(brown out) I have those connected between battery and ESC. But drag car motors pull a lot of power quickly. 

One small Glitch Buster always worked for me. I run Futaba S3004 servo's in all positions.( 3 - with 5th wheel/trailer legs) Also run extra run lights. With an electrical set up that will pull the power from the battery. (story for another day) But one capacitor still works on all my trucks. Look into your servo's.

Any way I'm glad it helped!

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Thanks @Tamiya Fan 1. It is the servo's I believe as I have tried some others and no issues. The ones I had are 4.8 - 6V ones, but they were high performance ones.

With the MFC's, is it safe to leave the battery connected (with the MFC switch off) for a couple of days when not in use, or is it best to fully disconnect the battery?

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Glad to hear it helped.

You should unplug it. Power will still run and drain your battery. At list unplug every day. I left one in about a week, (forgot), and it really took the battery voltage down. I thought I lost it. It won't hurt the MFC but it is good practice and batteries will be happier. Just always unplug when done using truck.

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What you are mentioning here timatc sounds like what I am trying to sort out on my Scania build which is fitted the mfc 3 fitted, my issue is with the programming it never seems to fully program indicators work from time to time the horn sound changes etc also it will not stay in 1st gear will only stay in 2nd and drops out of 3rd from time to time it’s becoming very frustrating as I’m so close to finishing the project. have a radio link t8fb 8 channel which coemwith the kit when I purchased it so I was under the impression that it would be fine with the mfc. I don’t know if it’s me doing something stupid I have followed the instructions word for word. Could it be I have a servo issue that’s causing this. I was wonder if I should purchase the futaba 4ywd transmitter as the instructions mention it as compatible. Any help will be greatly appreciated.

 

 

4B0E986C-FE36-4F5C-AE7D-5029DA900F0D.jpeg

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2 hours ago, SNIPEOverkill said:

What you are mentioning here timatc sounds like what I am trying to sort out on my Scania build which is fitted the mfc 3 fitted, my issue is with the programming it never seems to fully program indicators work from time to time the horn sound changes etc also it will not stay in 1st gear will only stay in 2nd and drops out of 3rd from time to time it’s becoming very frustrating as I’m so close to finishing the project. have a radio link t8fb 8 channel which coemwith the kit when I purchased it so I was under the impression that it would be fine with the mfc. I don’t know if it’s me doing something stupid I have followed the instructions word for word. Could it be I have a servo issue that’s causing this. I was wonder if I should purchase the futaba 4ywd transmitter as the instructions mention it as compatible. Any help will be greatly appreciated.

 

 

4B0E986C-FE36-4F5C-AE7D-5029DA900F0D.jpeg

It sounds like it could be the MFC-03 not set right. The MFC-03 has 3 - settings to set it up. I think the 2nd setting is for the shift servo travel. If it gets set wrong first and third gear may not engage all the way. The neutral position of servo, no command from transmitter would be second gear, why 2nd gear would always work. I had issues on the MFC-03 in this way before. Try to reset the MFC to "Default" setting and reset everything again to how the manual says for MFC. When done make sure your shift servo is travelling to both stops on transmission. (not to much or to little) Correct setting of MFC to RX is important.

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SNIPEOverkill,  

Answer to other questions.

The radio is probably O.K. High power servo's will give the MFC issues. Programming the MFC can go wrong. I think you can set the MFC-03 to default and then just do step one. Push MFC button, transmitter sticks Up/Down, L/R, and be done. Then check transmission setting for travel. I think that way will work but not positive. The 2nd setting for shift can be tricky if I remember right. Hope this helps.

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Thank you for the reply TF. What is a good low voltage servo and what sort of voltage should I be looking at, as most likely going to swap mine out.

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1 hour ago, SNIPEOverkill said:

Thank you for the reply TF. What is a good low voltage servo and what sort of voltage should I be looking at, as most likely going to swap mine out.

I use Futaba S3004, it has a power rating of 4.8V. (min.) I have had issues with a Hitec high torque servo, for a double steer, and had truck shutting down. Changed with a high torque Futaba servo and problem went away. The Hitec must pull more power (amps) than Futaba. Never ran tests to see why, but did fix issue. A good quality, regular servo, is all you really need. Your servo's may or may not be an issue?

I have a correction to previous posts. I was calling the 3rd setting of MFC-03 the 2nd one to set shifting.

Check to see if your transmission shifter is moving and stopping at it's end point for first/third gear. I think that is where your issue is?

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Think I’m going to swap out the servos, been having a look the s3004 are a little expensive the s3003 is cheaper and the only difference seems to me the s3003 has ball bearings and the s3004 is brushless the voltages Look the same. Would I be right in saying that.

 

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The S3003 should have bushings at servo horn, S3004 has 2 bearings for the horn, should both be brushed motor, analog, and are basically the same except for the 2 bearings. These are cheap for Futaba, but there are cheaper servo's out there. I've used Futaba since way back and always stuck with it. It is quality stuff and never failed me over the years.

 

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Those are digital I think and might give you issues do to the high power they pull. (digital servo thing) If they work post it, I'd like to know. Hope it works for you.

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They are spec’d the same as the s3003 and S3004 for voltage usage. It is a direct replacement for the S3003. Fingers crossed
 

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But it's digital. The difference is digital vs. analog servo. Digital servo's tend to use more power (AMPS) by there nature. Look up the difference between digital and analog servo's. You may be O.K.? I hope they do work for you.

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