b400 servo change went bad

[thirdkid]

So I crashed my 400 on the first flite. Being a newbie sucks. After fixing everything I find a striped servo. My lhs doesnt cary anything but a Eflite s75 and says that it should work no problem. Obviously hes been in the buisness for many years and knows more than me. I put it on and heres my prob, it doesnt center right. When you move the rudd stick left and let go it stops and does a little buzz sound for almost a minute until it centers. Move it right and it comes back to center fine(for the most part). Try to throttle up to about 35-40% and it starts spinning wildly. Calm it down to where it stops spinning and let it set and the servo moves a little and starts it spinning again. I thaught why not change the gears and have my ds75 back running right. Wrong, the gears on the s75 are way courser(for lack of better words) and they wont mesh with the main gear:thumbdown:. So is this little diff. in the 2 servos enough to throw everything out of whack?:confused:

[BKF]

When you swap out the servo on the tail, you have to sometimes reverse the rudder input on the radio. I think you may also have to reverse the gyro, but I'm not sure there.

Also, the Spektrum DSP75 servo has identical gears, and you can either buy the gear set or I was told by Horizon Hobby that it's a direct replacement for the DS75 servo. The nice thing is the Spektrum gears and DSP75 servos are pretty plentiful and only around 3 bucks for gears and 20 bucks for the servo.

So I crashed my 400 on the first flite. Being a newbie sucks. After fixing everything I find a striped servo. My lhs doesnt cary anything but a Eflite s75 and says that it should work no problem. Obviously hes been in the buisness for many years and knows more than me. I put it on and heres my prob, it doesnt center right. When you move the rudd stick left and let go it stops and does a little buzz sound for almost a minute until it centers. Move it right and it comes back to center fine(for the most part). Try to throttle up to about 35-40% and it starts spinning wildly. Calm it down to where it stops spinning and let it set and the servo moves a little and starts it spinning again. I thaught why not change the gears and have my ds75 back running right. Wrong, the gears on the s75 are way courser(for lack of better words) and they wont mesh with the main gear:thumbdown:. So is this little diff. in the 2 servos enough to throw everything out of whack?:confused:

[thirdkid]

So the s75 didnt work. Now I went and found a JR ds285 and tried it. It seems to work fine but now the prob is out of control tail spins. Move the stick either way and it will go crazy spinning and wont stop until you throttle down. Even at low throttle you can barely counter act the crazy spin. Now I am wondering if the gyro is the problem somehow. Help please, getting very agrevated with the whole thing.

[widower]

The first problem you mentioned where you move the stick left and the tail appears to stay to the left for a good period of time is normal for a heading hold servo. When in heading hold, the gyro is actively looking for the helicopter to move when you add rudder input. On the bench, your helicopter isn't turning when you move the stick.

In order to verify your servo travel, you need to turn off heading hold on the gyro by setting the gyro's gain to zero (below 50% is non-heading hold). At this point, set your endpoints using your radio. Once you have things set up properly, then you can turn heading hold back on by increasing the gyro's gain to what it was before.

As for the uncontrollable spins, this could be caused by not having the trim set correctly. Or, it could be because you need to flip inversion in the gyro.

In the manual for the heli, it talks about verifying the direction of the tail servo. If I recall correctly, watch the servo horn. Give right rudder input (heli turning right), and the top of the horn should move forward. Remove the rudder input. Then grab the tail and jerk it so the helicopter turns to the left. The gyro should then correct by trying to turn right and you should see the horn move forward then backward, not backward then forward.

[fdrotormedic]

I am sure that it is a servo issue, however, be sure that the belt is tensioned correctly and the the drive teeth have not been sheered off. I just recetly had this same issue and had replaced the servos with a set of Hi-Tec's. I automatically thought it was a servo issue but it ended up being the belt slipping and was not generating any blade speed on the tail.

[thirdkid]

I will check all of this out guys. I appreciate the help.

[thirdkid]

I checked it out and you were right. I had to reverse the gyro and set the end points, I think the final setting was 95%(may have to fine tune it later). Tried to throttle up to see if that stopped the tail spin and wouldnt you know it, the battery is low enough that it starts to spin and powers down. I will get a good charge on it tomarrow and let you know how it goes. Any suggestions on a good charger so I can charge it in house instead of on my car? Thanks for the help.

[carlo_the_wonder_frog]

I checked it out and you were right. I had to reverse the gyro and set the end points, I think the final setting was 95%(may have to fine tune it later). Tried to throttle up to see if that stopped the tail spin and wouldnt you know it, the battery is low enough that it starts to spin and powers down. I will get a good charge on it tomarrow and let you know how it goes. Any suggestions on a good charger so I can charge it in house instead of on my car? Thanks for the help.

Setting end points on the rudder channel does absolutely nothing to how far the rudder servo will move, it controls 1 thing and 1 thing only, PIRO RATE. If you want to spin slower, then adjust end points on the rudder down.

Best charger for the money is this http://www.fmadirect.com/Detail.htm?item=2218&section=45
Buy it directly from the web site, you will be extremely pleased with its ease of use. You must have a 12Volt DC power supply or a large car battery to use it though. DO NOT skimp on the charger, a good one will make life easy, a crap cheapo charger will not. If you really want a really good charger pony up the $400 for a Thunder Power 1010C with 210V balancer and a decent 12v power supply.

[BKF]

I was looking at the new Cellpro 10s charger, since it has a built-in balancer and can charge 2 Lipos at once.

Any idea what adapters i will need to connect the charger to the e-flite battery's balance lead?



Best charger for the money is this http://www.fmadirect.com/Detail.htm?item=2218&section=45
Buy it directly from the web site, you will be extremely pleased with its ease of use. You must have a 12Volt DC power supply or a large car battery to use it though. DO NOT skimp on the charger, a good one will make life easy, a crap cheapo charger will not. If you really want a really good charger pony up the $400 for a Thunder Power 1010C with 210V balancer and a decent 12v power supply.

[carlo_the_wonder_frog]

The cellpro 4s also has a built in balancer, it is after all a "balance Charger". the adaptor u need is http://www.fmadirect.com/Detail.htm?item=2196&section=45