RCCrawler Forums

max to crawl · 05-18-2006, 07:14 PM

ok here it is. i have 2 servos running 4WS with a Y harness. i have now burned up 2 servos on the front axle. swapped the first one with my LHS. lucky me. dont think they will go for it again. have not hurt the rear one at all. they are jrz650m servos. i opened this one up and found a really cooked little motor. all the gears seem to be good. but this makes the 2nd one. any ideas? i just dont think they are capable of holding the wheels in the turn position when crawling. i am running them on a seperate receiver pack of 6volts(1100ma). also not using servo savers. is the hitec 645 better?

hvydty1 · 05-18-2006, 07:53 PM

Ok, what is the torque rating of those servos, I can't seem to find their rating. The Hitec 645 are rated at 130 oz at 6 volt. I would have said that by not running servo savers, that would have been the problem, but since it is your motor that is frying, it is more probable that they are just not strong enough for your application. What size tires are you running? I have a Hitec 645mg on the front of mine turning BFT on Lst rims and are having no problems. I also run a rx pack.

insanerc · 05-18-2006, 08:17 PM

Servos can be a little more complicated than most people realize. I'm not sure of your exact setup yet but I have seen people run a y-harness and do the cut and splice to reverse one servo and fry the servo every time. If you're doing this then that is your problem. The cure for this is get a y-harness with the necessary built in circuitry to reverse one of the servos. Here is a link to one: http://www2.towerhobbies.com/cgi-bin...&I=LXAFN1&P=ML Also if you're running the servos off your BEC then you may not be providing the correct current to them making them work twice as hard as normal. In that case you would want to run an Rx pack. There are just too many things it could be that you need to eliminate and telling us more about your exact setup is important for us to try and troubleshoot the problem.

max to crawl · 05-19-2006, 04:10 AM

i am runnin imex k-rocks on maximizer wheels. i am using a Y-harness and seperate receiver pack. wires uncut, i plug them in and mounted them to my custom chasis according to how they were turning. they are supposed to have 140 oz. torque at 6 volts. i think i will go hitech 945 or 1/4 scale. these little jr's just dont seem to be able to do the job. got too much in this thing as it is......just as well make it right . thanks.

tkruger · 05-19-2006, 07:55 PM

Contact Horizon Hobbies. They are the distributor for JR servos. All JR radio gear has a 2yr warranty. There customer service is excellent. They may require proof of when it was purchased if the model has been around a long time.

Are you end point adjusted correctly for the front servo? If they are not then the motor may burn up when you move the wheels all the way to one side or the other.

05-18-2006, 07:14 PM	#1
max to crawl Newbie Join Date: Jan 2006 Location: kansas city Posts: 24	dual servo problems ok here it is. i have 2 servos running 4WS with a Y harness. i have now burned up 2 servos on the front axle. swapped the first one with my LHS. lucky me. dont think they will go for it again. have not hurt the rear one at all. they are jrz650m servos. i opened this one up and found a really cooked little motor. all the gears seem to be good. but this makes the 2nd one. any ideas? i just dont think they are capable of holding the wheels in the turn position when crawling. i am running them on a seperate receiver pack of 6volts(1100ma). also not using servo savers. is the hitec 645 better?

05-18-2006, 07:53 PM	#2
hvydty1 Quarry Creeper Join Date: Feb 2006 Location: Angier N.C. Posts: 387	Ok, what is the torque rating of those servos, I can't seem to find their rating. The Hitec 645 are rated at 130 oz at 6 volt. I would have said that by not running servo savers, that would have been the problem, but since it is your motor that is frying, it is more probable that they are just not strong enough for your application. What size tires are you running? I have a Hitec 645mg on the front of mine turning BFT on Lst rims and are having no problems. I also run a rx pack.

05-18-2006, 08:17 PM	#3
insanerc RCC Addict Join Date: Mar 2006 Location: Bedias, Texas Posts: 1,083	Servos can be a little more complicated than most people realize. I'm not sure of your exact setup yet but I have seen people run a y-harness and do the cut and splice to reverse one servo and fry the servo every time. If you're doing this then that is your problem. The cure for this is get a y-harness with the necessary built in circuitry to reverse one of the servos. Here is a link to one: http://www2.towerhobbies.com/cgi-bin...&I=LXAFN1&P=ML Also if you're running the servos off your BEC then you may not be providing the correct current to them making them work twice as hard as normal. In that case you would want to run an Rx pack. There are just too many things it could be that you need to eliminate and telling us more about your exact setup is important for us to try and troubleshoot the problem.

05-19-2006, 04:10 AM	#4
max to crawl Newbie Join Date: Jan 2006 Location: kansas city Posts: 24	i am runnin imex k-rocks on maximizer wheels. i am using a Y-harness and seperate receiver pack. wires uncut, i plug them in and mounted them to my custom chasis according to how they were turning. they are supposed to have 140 oz. torque at 6 volts. i think i will go hitech 945 or 1/4 scale. these little jr's just dont seem to be able to do the job. got too much in this thing as it is......just as well make it right . thanks.

05-19-2006, 07:55 PM	#5
tkruger Pebble Pounder Join Date: Jul 2005 Location: Greece Posts: 154	Contact Horizon Hobbies. They are the distributor for JR servos. All JR radio gear has a 2yr warranty. There customer service is excellent. They may require proof of when it was purchased if the model has been around a long time. Are you end point adjusted correctly for the front servo? If they are not then the motor may burn up when you move the wheels all the way to one side or the other.

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