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Thread: strange issue - MMP + Futaba T3PL

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Old 05-13-2011, 11:03 AM   #1
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Default strange issue - MMP + Futaba T3PL

I've got a weird issue going on that I'm not sure what it boils down to, any assistance would be great!

setup:

Custom Clod Buster chassis
Trinity Titanite brushed motors (I'm old school). Motors have .047u ceramic caps installed.
Duratrax 8.4v 4600Mah batts w/Deans
Mamba Max Pro - configured for brushed/reverse, BEC at 6v, cut off voltage disabled, no throttle/brake curves applied.
Futaba T3PL radio - linked to transmitter no prob.
Futaba s3305 servos.

I just got the radio yesterday, got it configured for 4ws, no EPA/TRIM adjustments, etc. MMP is only a month old, and I havent used it yet.

Batts are brand new - never used (and fully charged).

Steering is working fine in the respect that the servos are reversed correctly. Throttle works great (yes I reversed ch2).

However, when I try steering back and forth a few times, the receiver light goes to red, all the lights on the MMP light up, and I'm dead in the water until it resets.

I've was thinking it may have been a short on the servos since I had to solder on longer cables, but trying one at a time I still have the issue - just not as often. I've tried changing the BEC voltage on the MMP from lowest to highest - still have the issue. changed cut off voltage on the MMP to various settings, nada.

If I change the transmitters ch4 to INH (inhibited) it sort of works for a bit, but I have the same issue ultimately.

Also, the yellow light on the MMP is always flashing - I read this is due to the latest firmware? (which I applied a few weeks ago) is this correct?

Just a litle annoyed at this, as this is all new gear - radio/esc/batts, and I am chomping at the bit to run this thing on the street! this is my first project "back" into R/C in years..

any ideas, thoughts, questions, voodoo tricks to make this work w/o issue?

-Jim
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Old 05-13-2011, 11:17 AM   #2
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Have you tried an external bec? You could be overloading the internal bec w the dual servos.
Is you battery lipo or 7 cell nimh? Dont run cutoff w nimh.
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Old 05-13-2011, 11:17 AM   #3
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you might need an external BEC. I have run in to that problem with my mmp in my short course truck.
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Old 05-13-2011, 11:22 AM   #4
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havent tried external bec (yet). that would kind of suck of that was the cure... yet another battery to buy. heh.

batts are NIMH FWIW.
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Old 05-13-2011, 11:26 AM   #5
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I think you need a BEC like the Castle Creations CC BEC.

To find out since you are OLD SCHOOL, remove the red wire from your MMP and plug a receiver pack that you should have sitting around into the battery port on the receivers. Give it a drive and see if the problem goes away.

BTW - increasing the voltage should have made things worse and the yellow led flashing is normal.
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Old 05-13-2011, 11:31 AM   #6
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so, i just happened to locate one of those old 4cell batt holders for receivers from an old radio, plugged it right in, and it appears to have resolved the problem!

Superroo, which red wire are you referring to? the one from the MMP to the reciever? is it possible to remove w/o destroying anything? Am I running the risk of damaging the receiver with both the MMP BEC and the batt pack?
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Old 05-13-2011, 11:33 AM   #7
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just looked at the CC BEC.. might not be a bad idea.. ;)
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Old 05-13-2011, 11:41 AM   #8
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Quote:
Originally Posted by jhirte View Post
so, i just happened to locate one of those old 4cell batt holders for receivers from an old radio, plugged it right in, and it appears to have resolved the problem!

Superroo, which red wire are you referring to? the one from the MMP to the reciever? is it possible to remove w/o destroying anything? Am I running the risk of damaging the receiver with both the MMP BEC and the batt pack?
Yes the red wire in that lead. On the back side of the plug there is a little tab that you need to lift then slide the red wire out of the plug. Temporarly sheild it with some tape. You can use a hobby knife or little flat blade screw driver to get under the tab to lift it.
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Old 05-13-2011, 11:42 AM   #9
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Got it out w/o issue.. got the batt pack for (bec) taped in temporarily so I can drive this thing before I gotta split for work.

thanks so much! so glad I didn't end up calling Castle or Futaba!
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Old 05-13-2011, 12:11 PM   #10
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thx so much guys. thing runs great sans some adjustments, etc I need to make. trial run was pretty successful!
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Old 05-13-2011, 01:03 PM   #11
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Some MMP version 2 had a problem with in 9-12 volt range batteries not wanting to turn on the receiver. I had one and called them they were very fast trading out. Call them they will fix you right up. Now I can put up to 25 volts on my MMP with no worries
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Old 05-13-2011, 01:08 PM   #12
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BTW i run MMP , brushless and a synthesized 3 pl also just make sure your servos can take the voltage that you set the esc for I burnt a dig servo haha
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Old 12-29-2011, 08:01 PM   #13
Rock Crawler
 
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Default Re: strange issue - MMP + Futaba T3PL

Why would you run an Extra pack just for your BEC?
You can just solder the BEC wires to the ESC battery wires and it'll run off the main pack just fine.
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