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Help me diagnose R/C Radio problems (Vintage Futaba)

Help me diagnose R/C Radio problems (Vintage Futaba)

Old 10-31-2011, 05:12 AM
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Default Help me diagnose R/C Radio problems (Vintage Futaba)

Hi there, this is my first post
Well I dusted off my old Tamiya Manta Ray with Futaba Megatech Junior radio gear.

The car has an upgraded motor, (Dyna-Run Super Tourer) and a 2000mAh battery.

I charged up the 20 year old AA batteries and 5/8 still worked!
Then charged the 2000mAh battery which still worked also!

The car ran well, however sometimes it would stop responding all together, or only work in reverse not forwards. Sometimes stuttering. Strange how it would only go in reverse. Once it took off in reverse by itself until i turned off the controller. There is a connection issue with the radio gear somewhere i suspect. (this was in close range so not a low signal issue)

Any ideas where I should look first?
P.S while using it the first time, the molex connector from the battery melted
I guess as the connectors were old and tarnished.
I have owned this since 1991!

Cheers
Sam
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Old 10-31-2011, 02:41 PM
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wow this forum moves fast.

Well any ideas where i should check wiring first, or solder joints?

Is this the Futaba receiver perhaps over heating or failing? (It gets VERY hot with the dynarun and 2000mAh battery)
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Old 10-31-2011, 02:46 PM
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If it would only work in reverse, I'd try fiddling with the trim. Apart from that, no idea.
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Old 10-31-2011, 06:50 PM
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Wow...you're talking about a twenty year old set-up....there are so many things that could be wrong, there really is no way to diagnose this.

I wish you good luck.
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Old 11-01-2011, 03:12 AM
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Hah yeh I know ok I'll get out the multimeter and look for shorts or dry solder joints.
I think the controller is fine.
Perhaps the radio gear on the car has some dodgy wiring.

Need to replace molex connectors also.
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Old 11-01-2011, 01:02 PM
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It would only go reverse when it was having issues, shake car, or disconnect battery and reconnect and it would go again.
Not trim or setup, it's a wiring issue or failing gear at temp.

I'll check it out
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Old 11-01-2011, 01:22 PM
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Every old radio system I've played with, 2 of my Futabas, an olf KO, and a friends 2 Futaba systems, all have glitching issues of some sort. That's the nature of the best with old AM or FM based systems. More frequencies are open for use now infringing on those old radio frequencies. The worst interference happens right around sunset for some reason. I just upgraded to 2.4. It's cheap and no run issues.
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Old 11-01-2011, 01:31 PM
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Do you have a spare set of crystals to troubleshoot with? I had similar issues with my Airtronics M8 (75mhz) on one channel, but I swapped crystals and all of my issues went away.
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Old 11-06-2011, 09:51 PM
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No spare crystals. I don't think this is interference either as it seems far more like a connectivity issue.

I'll get the multimeter out and have a look sometime.
Gotta fix the melted molex connector first though
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