R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Nitro Off-Road

Reply
 
Thread Tools Search this Thread
Old 08-29-2009, 08:43 AM   #1
Tech Adept
 
Join Date: May 2009
Location: Iceland
Posts: 206
Send a message via MSN to helgso
Default Problem with my battery power, servo or failsafe

Hi. When I was driving my RC just now, it ran good. But, if I went to full throttle, it would stay in full throttle for 1-3secs then stop throttling (even though I was still telling it to throttle). Then, after the throttle stops, I can't control the car any longer, it idles, but doesn't respond to the radio.

I check the failsafe and it has a red light on it (meaning that it has kicked in maybe because of low battery power). So, I turned the kit off and switched batteries. Again on the track and full throttle, bang the same thing. Just after having ran the car through 1/2 a tank (I couldn't believe the batteries onboard would only last for 1/2 a tank so I turned it off, waited a sec and turned the kit back on)

Then, after turning it back on the failsafe has a green light on it indicating that everything is fine. Is my failsafe the issue, the servo or what?
helgso is offline   Reply With Quote
Old 08-29-2009, 10:46 AM   #2
Tech Lord
 
Frank L's Avatar
 
Join Date: Dec 2008
Location: NorCal
Posts: 12,500
Trader Rating: 148 (100%+)
Default

How does the throttle servo look on the bench, are the end points set right. I recently installed a new throttle servo and the end points looked good, no binding, but on full brake the servo would have a problem and loose connection for a few seconds. I adjusted the end point and problem solved. If end points are not set correctly then the servos will drain a ton of power from the battery, that could send a low voltage signal to the failsafe and set it off. Just a thought...
__________________
- X-Ray/ RC America Team Driver - MKS -
- XB8 - XB8T - XB8 E - OS Spec III - B2102 - 4PXR -
~ SSC ~ Godfather ~ Ironman ~ ButterySmooth ~
Frank L is offline   Reply With Quote
Old 08-29-2009, 10:56 AM   #3
Tech Fanatic
 
Join Date: Sep 2008
Posts: 864
Trader Rating: 21 (100%+)
Default

take the batt cover off and while keeping an eye on the failsafe try going to wot on the bench (engine off) and see if the light goes red then set epa also check linkage for binding. you can also take out the failsafe and check throttle to see if the radio stay connected.
TopGearRC is offline   Reply With Quote
Old 08-29-2009, 11:08 AM   #4
Tech Adept
 
Join Date: May 2009
Location: Iceland
Posts: 206
Send a message via MSN to helgso
Default

Quote:
Originally Posted by Frank L View Post
How does the throttle servo look on the bench, are the end points set right. I recently installed a new throttle servo and the end points looked good, no binding, but on full brake the servo would have a problem and loose connection for a few seconds. I adjusted the end point and problem solved. If end points are not set correctly then the servos will drain a ton of power from the battery, that could send a low voltage signal to the failsafe and set it off. Just a thought...
I attached OLD pictures, one overview other underview (These are not new pictures!! This is when I was still putting the rc together, now it is fully functionable). Could you mark where the "end points" of the servo are and how to configure them?

Thanks!
Attached Thumbnails
Problem with my battery power, servo or failsafe-underview.jpg   Problem with my battery power, servo or failsafe-overview.jpg  
helgso is offline   Reply With Quote
Old 08-29-2009, 11:22 AM   #5
Tech Adept
 
Join Date: May 2009
Location: Iceland
Posts: 206
Send a message via MSN to helgso
Default

Quote:
Originally Posted by xjqkz View Post
take the batt cover off and while keeping an eye on the failsafe try going to wot on the bench (engine off) and see if the light goes red then set epa also check linkage for binding. you can also take out the failsafe and check throttle to see if the radio stay connected.
I turned on the electronics, and went to full throttle with the engine turned off. The servo could open the carb and keep it open as long as I wanted. The failsafe didn't engage.

Could this be because my servo becomes tired after some time, then when I go to full throttle it gives up (disconnects for a bit), the failsafe engages and thinks the car is out of battery power?
helgso is offline   Reply With Quote
Old 08-29-2009, 11:45 AM   #6
Tech Lord
 
Frank L's Avatar
 
Join Date: Dec 2008
Location: NorCal
Posts: 12,500
Trader Rating: 148 (100%+)
Default

When you go to full throttle you want just a little bit left so the carb can open up a little bit more due to chassis flex. Also listen to the servo if it is straining then its too much. Same thing with brake. Just make sure the servo tray is not moving at full throttle or brake.
__________________
- X-Ray/ RC America Team Driver - MKS -
- XB8 - XB8T - XB8 E - OS Spec III - B2102 - 4PXR -
~ SSC ~ Godfather ~ Ironman ~ ButterySmooth ~
Frank L is offline   Reply With Quote
Old 08-29-2009, 01:43 PM   #7
Tech Adept
 
Join Date: May 2009
Location: Iceland
Posts: 206
Send a message via MSN to helgso
Default

Quote:
Originally Posted by Frank L View Post
When you go to full throttle you want just a little bit left so the carb can open up a little bit more due to chassis flex. Also listen to the servo if it is straining then its too much. Same thing with brake. Just make sure the servo tray is not moving at full throttle or brake.
Tray, is that the metalbit under the servohorn? If so, it certainly moves when at full throttle but not when full brakes are applied.

Take a look at this video I made: http://www.filefront.com/14425127/IMGP3168.zip
helgso is offline   Reply With Quote
Old 08-29-2009, 04:16 PM   #8
Tech Adept
 
Join Date: May 2009
Location: Iceland
Posts: 206
Send a message via MSN to helgso
Default

I looked at a thread: Problems with Futaba 3PJ and saw that having your antenna bent or crystals bad would cause this kind of problem.

Thing is, my antenna is a bit bent, and my crystals are from 2006 (although they aren't really that much used). Could this be the problem?

P.s. I have the Futuba JRP3 radio
helgso is offline   Reply With Quote
Old 08-29-2009, 04:20 PM   #9
Tech Master
 
Join Date: Jul 2007
Location: Rossville Ga
Posts: 1,398
Trader Rating: 10 (100%+)
Default

Try ruling out the failsafe by bypassing it. I would also do a distance test by having someone hold the car and the walk the radio away and see how long you go before losing signal.
bigde2001 is offline   Reply With Quote
Old 08-29-2009, 04:23 PM   #10
Tech Adept
 
Join Date: May 2009
Location: Iceland
Posts: 206
Send a message via MSN to helgso
Default

Quote:
Originally Posted by bigde2001 View Post
Try ruling out the failsafe by bypassing it. I would also do a distance test by having someone hold the car and the walk the radio away and see how long you go before losing signal.
So with the failsafe uninstalled, somebody holds the car, another walks with the radio away and check how far you can go before signal is lost?
helgso is offline   Reply With Quote
Old 08-29-2009, 04:25 PM   #11
Tech Master
 
Join Date: Jul 2007
Location: Rossville Ga
Posts: 1,398
Trader Rating: 10 (100%+)
Default

Quote:
Originally Posted by helgso View Post
So with the failsafe uninstalled, somebody holds the car, another walks with the radio away and check how far you can go before signal is lost?
yes, you should be able to get aleast 200 ft away.
bigde2001 is offline   Reply With Quote
Old 08-29-2009, 05:33 PM   #12
Tech Master
 
Join Date: May 2008
Posts: 1,771
Trader Rating: 7 (100%+)
Default

You say you have low battery power, what receiver pack do you have? Do you have the 4 AA's or a rechargeable 5 cell receiver (rx) pack?

For end points (EPA) there should be a feature on your radio that has that. Look in the manual. I searched waht radio you had and nothing came up. Can you find a link? Anyway you want to adjust the EPA so when you are pressing wide open throttle (WOT) with the engine OFF, you can pull the linkage that connects to the carb slide and you can still pull it another 1-2mm. Then for brake you dont want the EPA's up all the way as that might stress the servo and break it. What I do is press full brake, then hold 1 front tire, and turn the other front tire. I try to get it so the break is a 40%. Think of it as 100% locked, 0% no resistence. It is just a feel thing. Then for the rear, try 60% brake. There are small adjuster things that adjust the brake, but if the brake lock then you definitly want to turn down the EPA for brake. For steering, you go as far as you can before you hear the servo is pushing too far and hitting something else. Or reduce EPA's on stering a little more if you dont need great steering and that will help save the servos also.

I remember when you first got that car trying to get it running, approx. how much have you spent getting it back to running condition? Hope this helps.
__________________
Losi 8ight 1.5 ~ 8T ~ XXX Buggy ~ Mini-Baja

The o''le saying goes, pay me now, or pay me later, because you gonna pay me. "Pearl_414"
Chris__RC is offline   Reply With Quote
Old 08-30-2009, 05:26 AM   #13
Tech Adept
 
Join Date: May 2009
Location: Iceland
Posts: 206
Send a message via MSN to helgso
Default

Quote:
Originally Posted by Chris__RC View Post
You say you have low battery power, what receiver pack do you have? Do you have the 4 AA's or a rechargeable 5 cell receiver (rx) pack?

For end points (EPA) there should be a feature on your radio that has that. Look in the manual. I searched waht radio you had and nothing came up. Can you find a link? Anyway you want to adjust the EPA so when you are pressing wide open throttle (WOT) with the engine OFF, you can pull the linkage that connects to the carb slide and you can still pull it another 1-2mm. Then for brake you dont want the EPA's up all the way as that might stress the servo and break it. What I do is press full brake, then hold 1 front tire, and turn the other front tire. I try to get it so the break is a 40%. Think of it as 100% locked, 0% no resistence. It is just a feel thing. Then for the rear, try 60% brake. There are small adjuster things that adjust the brake, but if the brake lock then you definitly want to turn down the EPA for brake. For steering, you go as far as you can before you hear the servo is pushing too far and hitting something else. Or reduce EPA's on stering a little more if you dont need great steering and that will help save the servos also.

I remember when you first got that car trying to get it running, approx. how much have you spent getting it back to running condition? Hope this helps.
I thought I had low battery power, but I'm not sure. I have 4x AA batteries onboard and 8x AA batteries in radio (not rechargeable batteries). The radio I have is the JR XS3, it was included with the truck I have Losi LST1 (sorry it was not futuba JRP3). Link here and manual: http://jrradios.com/Products/Default...ProdID=JRPM129

As for 40% breaking for front tires and 60% breaking for rear, I am unable to do so. You see, the breaks apply to all my wheels (my truck is 4x4 drive) Losi LST1. But I would be able to adjust the breaks on all four wheels, like it would break 60% on all wheels when I'd say it to fully break.

Dollars spent on getting the car running include:

I bought a new engine (Mach 427), bearings, clutch shoes and springs and a flywheel for 163,15$.
I bought a failsafe for 8$
Losi Thread lock 7,47$
Green slime 7.38$
Infrared Tempature sensor 17,94$
WD-40 6$
Gasket Material 11,25$
Shipping and handling cost for all above to Iceland: 33$

50$ extra for required replacement parts
And about 20 hours+ of working time (I had never done this before so it took some time)

Grand Total: 304,19 $

Last edited by helgso; 08-30-2009 at 05:41 AM.
helgso is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
Problems with Futaba 3PJ Morpheus2be Singapore R/C Racers 6 09-30-2002 02:09 AM



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 04:06 PM.


Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net