Help! Servos aren't working when hump pack is plugged in

[msulifter37]

Ok so I just got done doing a FLM mid tank with a 250cc tank. I also replaced the AA batterys with a hump pack (2600 MaH from www.onlybatterypacks.com). I charged the pack and plugged it in. Turned the switch on and nothing happened. I turned it off and back on again and my throttle servo gave a little twitch but nothing else. The steering servo shows no signs of life. So I thought "the hump must not be fully charged". So I took it out and plugged the AA pack into the truck and got the same exact response from the servos. This shows that it isn't a problem with the battery charge. What the *censored* is wrong? I have checked my connections 100 times. Everything is hooked up right. I used to have reverse but had to take it out when I did the mid tank. Could it have something to do with not using the reverse mixer anymore? Did the servos go bad from sitting for a few months during the winter? Can the receiver go bad? Oh, I should add that when I turn the switch on and the throttle servo gives a 'twitch', it won't respond when I pull the trigger on the radio.

Info about the gear I am using:
Steering servo - Towerhobbies Super Torque TS-70
Thottle servo- Towerhobbies STD TS-53
Radio and receiver - Futaba T3PM-FS

 

[AllanQ]

Not familiar with Futaba or the FM system, but has the TX and RX setup to work with each other. Only other thing I can of are the servo wires in backwards. this probably doesn't help much, but good luck.

Here is what I read about your TX and setting up the radio system you have...
http://manuals.hobbico.com/fut/3pm-fm-fs-manual.pdf

 

[msulifter37]

Well, I have the same gear now as last year and it all worked just fine a few months ago before winter. I just wonder why the servos don't react when the power switch is turned on, except for the throttle servo twitching when the switch is turned on. And if everything plugs in correctly, wouldn't that indicate the servo wires being plugged in the right way? I have the steering servo plugged into CH1 and throttle/brake plugged into CH2. CH3 is emptly and the power switch is plugged into the B/C plug

 

[AllanQ]

I have plugged in the servo wires backwards before and had the same symptoms you have. Other than the TX settings being correct, I am out of ideas. Sorry I am not much help here, but I am sure someone will come along with some more ideas.

 

[msulifter37]

I guess explain to me what you mean by plugging in the servo wires backwards. The wire comes out of the servo and plugs into the receiver, so how can you plug it in backwards?

 

[oregonmud]

Try a different RX/TX or just replace the crystals and see if that helps. The black/brown (ground) wire should be on the outside if I'm not mistaken. maybe post up a pic of the way you have it all mounted and maybe somebody will spot your problem.

 

[AllanQ]

By backwards I mean that the red wire of the servo is connected to the (-) ground terminal and the black is connected to the (+) power terminal on the rx.

 

[canucksavage]

Did you buy the new switch harness for the hump pack so you don't have to unplug to recharge (i crossed my wires up when i added new switch). When that happened I lost throttle/brake but not my steering control

 

[f1n3sse]

sounds like you might have a bad rx if your wires aren't reversed and your crystals are good

 

[Hotelcalif]

Are you sure the AA pack is good voltage? Are your servos a Futaba J plug?Looking at the Rx is the black wire on the servo lead to the right on the 3 wires?

 

[msulifter37]

The AA battery pack has brand new AAs in it. And the hump pack is fully charged. I'm not sure if the servos have Futaba J plugs but the servos and radio and receiver are all the same as last year and everything worked fine at that time. I played around a little with the truck today and I am positive the servo wires are plugged in correctly to the receiver.

I do not have a new switch harness for the hump pack. Just the one I used when I had the AA pack.

I used to run reverse before the mid tank. I know that you have to program the reverse mixer when you install it. So do you have to do something to reprogram the servos when you remove reverse? Just for kicks I plugged in the reverse mixer again with the 3rd servo and turned the switch on and the red light on the mixer when on but nothing happened with the servos. No response to radio either.

I have steering plugged into CH1 and throttle into CH2. Thottle will still give a little twitch when the power switch is flipped on but then will not respond anymore. Steering doesn't do anything. I removed steering plug and plugged throttle into CH1 and got the slight twitch when power was turned on. I then plugged throttle into CH3 and it twitched again when power was turned on. I repeated with steering and got no response at all.

There are no pinched wires or metal on metal. I am so frustrated.

 

[Hotelcalif]

Try to bypass the switch and plug the hump straigh into the Rx. See if that works. That will tell if the switch is bad.

 

[dravage]

if you use crystals it could be the crystals because i had a problem very similar to yours

 

[Hotelcalif]

Did you get this sorted out?

 

[AllanQ]

I think there are two threads going on about the same problem. Will check when I get home.

 

[frddyj]

i know you plugged the battery direct into your Rx & got the same results & you do not use crystals cuz its a 2.4Ghz radio.

I'm thinking that your getting power to the servos, otherwise you wouldnt get a 'twitch'

I'm also thinking that since you had your radio equipment on the shelf over the winter that your Receiver is not in sync with your transmitter so when you try to send a signal (like turn the wheels or use throttle/brake) your receiver is not picking up the signal.

Go into your owners manual & sync your Rx to your Tx; if you don't have the owners manual, then let me know & i will scan and email it to you.

 

[msulifter37]

Hey, I flipped all servo plugs in the Rx and got the same results. I made sure the Rx and Tx were on the same frequency. I also looked thru my manual but couldn't find anything that talked about "syncing" my tx and rx. There was an option to reset the rx setting back to default, so I did that. But thats all I could find. I don't know what the problem is and at this point, I feel like I am better off just getting a new system. I could sit here all summer and never figure out the problem, or I could just replace everything and go back to enjoying my savage. Thanks for all the help though guys. I wish one of you could just sit down with my truck and tinker with it.

 

[oregonmud]

Where are you from? I'm sure someone would be willing to help you. This is a huge site with members from all around the world. You might get lucky.

 

[frddyj]

I also looked thru my manual but couldn't find anything that talked about "syncing" my tx and rx. T.

its on page 24 under "initial Set Up, How to link the transmitter and the reciever" if its not the same page in your book, pm me your email addy & i'll scan & send it to ya tomm.

hate to see ya go & drop the coin on new stuff if we can get yours working, lets give it this 1 last shot.

freddy