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Old 01-23-2008, 02:07 PM   #1
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Default What are your Rx temps like?

I posted this in the radio section but have had no reply, so i'll try here.

I've been having intermittent signal loss problems and was wondering if anyone could offer some advice.

About 6 months ago i got a Futaba 3PK 2nd hand, it had the fm module, and went great except for the occasional loss of signal which i could never nail down.
2 months ago i got a Fasst system with 2 recievers, 1 for my RC8 and 1 for my electric drifter.
Now i can run the drifter all day without a prob, consecutive 30 + min battery runs, never had a proble.
Thing is, in my RC8 (and my Hong Nor 9.5 before that) once i start to run nostop for longer than about 30 mins, I start getting intermittent signal loss.
Tried everything i could think of, was running lipo's, changed to nimh, same, both recievers act the same.
Long story short, and getting tired of not being able to find the problem, i tried a little test.

I put 1 of the revievers and a fresh nmih in the oven,, turned everything on, and started to bake at 35'C. Every 10 mins or so i upped the temp 5C, until low and behold at 60'C the led turned from green to red on the Rx, same thing i'd seen at the track.
Took it out and plugged/unplugged the batt until it stayed green again, took maybe 15 seconds sitting in my hand, it was hot but not excessively.
Put it back in and tried again, sure enough about 5 mins later it went red again.
Tried the other receiver with another fresh batt, 12-13 mins later, same deal, led went from green to red and stayed red until the Rx cooled slightly.

So it would seem my Rx's, R603FS's, will not work well above 60'C, and to me that seems to low, when you think its sitting near a motor running at 110-115'C. Here in Aus summer temps can be extreme in the sun on a hot day, i wouldn't be suprised if temps in a car sitting in the sun, without the motor running could exceed 45-50'C easy, so that doesn't leave much room to play with. Computer components run at 70-80'C and above all the time.

Whats your thoughts, 60'C too hot, maybe someone with a temp gun could check they're Rx after a long run.

Sorry for the long read, thanks all.
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Old 01-23-2008, 02:32 PM   #2
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Try putting some heat shield tape made out of Nomex or like some exhaust wrap stuff on your reciever box... Losi sells some of the type i think and if you put it on the outside and inside of your reciever box I bet it would help actually it would fix the problem. Nomex is a really good insulator and does not let heat pass through it. Also putting your electronics in the oven??? I would be verrrrrryyyyy scared of doing that, but I guess it did give you results! In the states 60 degrees celcius is like 140 degrees fahrenheit and that is pretty toasty for electronics. I would submit this to associated to let them know that putting the receiver box that close to the engine could cause problems... Also my computer parts stays around 60 degrees celcius go to amainhobbies.COM and search nomex and it will bring up the tape im talking about! Hope this helps! Oh and there is a guy at my track who runs the RC8, but he uses spektrum... so maybe thats a fix too.
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Old 01-23-2008, 03:54 PM   #3
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I would think that the reciever should be cooler than that in the car. What servos are you running and do both recievers due the same thing in the car or only one does it?
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Old 01-23-2008, 03:59 PM   #4
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My RX for my 3PK is just as cool as it was when I installed it in the car I was running.
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Old 01-23-2008, 04:25 PM   #5
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Thanks for the responses everybody

Firstly, believe me i dont get in the habit of throwing stuff in the oven at the 1st sign of problems, its a last resort, the damm thing cost me an a main win on the weekend, and the oven was the only way i could think of replicating the problem, by now i'm positive its heat related...
I'll try some reflective insulation tape, good idea, i might also try raising the reciever box up off the chassis a bit more.
Strangely enough 2 other local guys run an RC8/3PK FASST combo and haven't had any probs, not sure they've run 30 mins + though...

ATM i'm running 2 1015's, have also run 1 x 1015 and 1 x futaba 9351 in the past, same deal. Tried both recievers, same deal. As i said i'm pretty sure now its heat related, when i did the oven test it was only reciever and batt, no servo's or transponder.
Honstly i cant beleive these Rx's are only good up to 60"C, its not unusual to see 45-50'C in the sun in summer here, i'm sure they just had court temps of over 50'C reported from the Aussie tennis open in Melbourne this week, add a nitro motor a couple of inches away and there's no margin left.

I guess what i need is some actual temp measurements taken from a car just off the track after a good, long run, if someone could temp the reciever/box/chassis and post the findings i'd really appreciate it, its very hard convincing my buddies to throw their rx's in the oven... pussies.
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Old 01-23-2008, 04:35 PM   #6
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My friend runs the RC8 with the R603FS unit with no problems. He actually used the Futaba and a Ace servo this weekend. You do have the foam padding under the unit in the radio box, correct?
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Old 01-23-2008, 04:40 PM   #7
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UMM, there's a thin foam pad that came with the kit, i installed that inside the box on the bottom, and the receivers are wrapped in sponge rubber/foam stuff as well, thanks man.
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Old 01-23-2008, 07:25 PM   #8
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Quote:
Originally Posted by Alex Kaos View Post
UMM, there's a thin foam pad that came with the kit, i installed that inside the box on the bottom, and the receivers are wrapped in sponge rubber/foam stuff as well, thanks man.
Maybe you should try taking the sponge/rubber/foam stuff out as it could be insulating everything and heating it up more than it should be. And suffocating it by not letting what little air there is in the box to actually pass over the rx.
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Old 01-23-2008, 10:52 PM   #9
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Not to be redundant if you've already done this, but did you test both receivers in this way? And have them both cut out at a similar temp?
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Old 01-23-2008, 11:16 PM   #10
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I have had the same problem you speak of. I have the same car with the same radio gear. With exception to the servos. I run Hitec 5955's. I run lipos with the regulator inside the radio box. What I did to solve the problem was simply rearrange my batt and electronics. I was having the trouble with shuting down when the reciever was located towards the front of the batt box. Moving the reciever to the back and batt in front solved the problem for me. Those 1015 can give you a problem also. They draw more current than other servos on the market. I had a friend running them in a Mugen. He tried everything to stop the same problem, and finally figured out it was the servos current draw that was overheating things. Hope this helps you out.
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Old 01-23-2008, 11:27 PM   #11
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Quote:
Originally Posted by pistolpete View Post
I have had the same problem you speak of. I have the same car with the same radio gear. With exception to the servos. I run Hitec 5955's. I run lipos with the regulator inside the radio box. What I did to solve the problem was simply rearrange my batt and electronics. I was having the trouble with shuting down when the reciever was located towards the front of the batt box. Moving the reciever to the back and batt in front solved the problem for me. Those 1015 can give you a problem also. They draw more current than other servos on the market. I had a friend running them in a Mugen. He tried everything to stop the same problem, and finally figured out it was the servos current draw that was overheating things. Hope this helps you out.
Sounds like you need a BLS451 servo instead then.
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Old 01-24-2008, 04:32 AM   #12
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Naw,I will never give up on my Hitec's!!! I was using Futaba 9451's before and kept stripping gears. I had never had this issue with my MBX5R. I have run through several 30 min mains since I rearranged things without any issues. Problem solved!
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Old 01-24-2008, 07:14 AM   #13
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My friends and I have never stripped these Futaba gears yet. We burn them out and have to replace them, but the gears worked for us. You know the gear is $7 for 5 of them.
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Old 01-24-2008, 02:34 PM   #14
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Great guys thanks for the replys

Don't really want to run without any foam, might have to figure out some air flow thou..

Yep tried both receivers in the oven, same result, 10-13 mins @ 60'C and they're done. I still think thats too low for electronics to be having probs..

pistolpete, very interesting thanks mate, sounds like a similar thing. It worries me things seem so close to the limit thou, what are the ambient temps where you run? As it was i have my batts on the inside of the box, closest to the motor, and my Rx on the outside(still inside the Rx box, the switch side of the box), as far from the motor as possible, but i'll try your arrangement.
I will also try a diff set of servo's i guess, but i'm still dissapointed. Its a 3 channel reciever, but if its struggling to supply enough power to 2 digi servo's, there'd be no chance of running 3 servo's then.
sigh, you think your doing the right thing getting good gear and stuff like this happens...
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Old 01-24-2008, 06:19 PM   #15
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I run my spektrum rx with nothing other than the bottom foam pad. I run a 6volt nimh rx batt in the front and the rx in the back of the box. Don't see much of a reason to bundle it all up unless you're running in wet/muddy conditions.
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