Installing JR DS285s and DS3400G Servos on the Blade 400 - HeliFreak
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Old 09-13-2008, 05:41 PM   #1 (permalink)
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Post Installing JR DS285s and DS3400G Servos on the Blade 400

Installing JR DS285s and DS3400G Servos on the Blade 400

I have learned quite a bit about the hobby from the Heli Freak forum. I have found a wealth of information that has helped me through crash repairs, and general troubleshooting. As someone new to the hobby, I must admit crash repairs were a concern.

Let me clarify that while I learned to fly the CX2 very well in short time, the Blade 400 (B400) is a very different experience. One of the initial (and frustrating) reactions I had with the B400 out of the box (I did dial up some expo on the DX6i), was I could not hold the hover nearly as well as with the CX2. I seem to float about and a few feet higher it was a bit easier but still not solid. During a recent flight it felt as if it got away from me during the last few seconds, so I set it down. I had a good practice session up until that point, was not sure what the issue was. I took off again; at about 6’ in a hover the B400 started to move forward pretty quickly on its own. I managed to pull back enough to flare up and touchdown, tipped over but no damage luckily my neighbor’s lawn was tall, cushioning my landing.

I did some research here on the Heli Freak forum; found that some folks had reported similar situations as a result of issues with servos. I checked my B400 and sure enough the entire forward (ELEV) servo had failed no control at all. It was more luck than skill that I managed a somewhat controlled landing!

After more reading I came to the same conclusion many of you had, the stock servo’s are one of the areas E-Flite had to make a compromise in order to meet a price point. Now the question was what servos do I want to purchase for my B400. Clearly, the thought of driving my B400 into the ground because of a bad servo did not sit very well. After reading several discussions and recommendations, I made the decision to go with JR Servos. Specifically, I went with the following JR “Mini Heli Performance Servo Set”:

· Cyclic – JR DS285 x3
· Servo – JRDS3400G x1

My experience with installing these servos is what I want to share, hopefully providing others new to the hobby, a good idea of what it involves. I found a number of sources online, but there was no one discussion detailing the installation from start to finish.

Note: The information here is based on my personal experience. I welcome any additional information that will help. The new servos made a huge difference with handling and I love how this bird flies now. So I guess that means I did something right.

Prerequisites & What to Know Before Starting

Note direction of movement on all your control inputs. They should be as described in the B400 instruction booklet. If they don’t already, you are replacing other parts I am sure!

1. Q: Why?
A: The new Servos will be reversed as compared to the stock servos.

2. Q: Will I need to worry about going through the radio binding process after new servos are installed?
a. A: No

3. Take a few pictures of your heli, note the tie wraps near each servo, the ESC and Radio receiver below. You will be removing the existing tie wraps and pictures will help later.

4. For each servo, note the configuration of the ball links with the stock servos, they clip on the outside of the servo horn. These unscrew from the servo horn. With the three JR servo’s, you will want to connect the ball link on the inside so these ball links will face the frame of the heli when done.

5. The JR Servos come with screws and rubber grommets. Take a look at these, note how the grommets mount, they will be used.
a. Note: I found a number of different discussions here on use or not using these. Including changing the screws since they are too small. I ended up using a washer and the screws and grommets.
6. JR Servo horns - I ended up cutting those on the forward servo leaving two horns one for each ball link. The other cyclic servos I did not modify. The Gyro Servo (DS3400G) – we will get into that later…

7. Turn your DX6i radio ON. Center all TRIM settings at this time.

8. Center sticks on the Radio.

9. Take a look at the wire length on the DS285 servo as compared to the wire length on the forward stock servo. The JR is shorter. I believe there are extensions available, but I did not have them. I ended up having to move the AR6100E receiver forward. So if you don’t have an extension, be prepared to do the same.

10. Disconnect Motor power cables under the battery tray. A safety precaution to avoid injury later while you power up to center servo’s etc.

Installing the JR DS285 Servos
Important: Only remove and install one servo at a time. This avoids any confusion as to where the new servo connector plugs into on the receiver.

Removal and Installation of the Forward (ELEV) Servo
1. Remove tie wraps on wiring to servos and those on the AR6100E receiver.
2. Disconnect the ball links from stock servo horns.
3. Trace the wire and unplug the connector from the receiver. Note: Black (neg.) wire is lowest. Pay attention to the route the servo cable takes. Avoiding gears for motor etc.
4. Remove Velcro battery fastener from frame.
5. Unscrew the stock servo mounting screws
6. Remove servo (I found lifting front of it up 1st was easier).
7. Remove the ball link from the servo horn. Use the smallest allen wrench that came w/the B400 kit. This will be installed in new servo horn the same way they were removed.
8. Insert the ball link onto the new servo arm (there are two for this servo). Remember you need to make sure the ball faces inward (toward the frame) when you attach the servo horn to the servo. I found if I put the servo horn on the table, used the allen wrench to apply pressure and start screwing it in, you can then pick it up and continue to screw it in until tight.
9. Move the AR6100E receiver forward, but not too close to the ESC. I left enough room to put my little finger between the two. That was enough to let the forward servo cable connect to the AR6100E. It was a bit difficult to unstick the receiver from the frame, but the mounting tape was fine for attaching the receiver back to the frame in its new position.
10. Mount the new servo using rubber grommets, screws (either with washer or using larger screws). Make sure you route the cable properly, avoiding the toothed gears for the motor etc. It’s shorter so you want the straightest run to plug into the receiver.
11. Connect cable to receiver; make sure you get the black negative cable right. It should be as the others, lowest.
12. Mount the servo horn (push it on, but do not screw in).
13. Leave ball links disconnected for now.

Removal and Installation of the Cyclic Servos
14. Follow same procedure as used for forward (ELEV) servo.
15. These cables are long enough and now that the receiver has been moved forward, no issues. Just pay attention to the cable routing and connecting it properly to the receiver.
16. Attach the servo horn (just push it on) do not use center mounting screw yet, leave the ball links disconnected.

Finding “Center” for the Cyclic Servos
17. Make sure radio sticks are centered.
18. Make sure you disconnected the Heli motor!
19. Make sure all servo horns remain disconnected, all ball links disconnected.
20. Turn the DX6i on. Set throttle hold (does not hurt to be paranoid here!)
21. Make sure trims are all centered
22. Connect the Battery on the B400 up. You of course will not get the usual beep indicating all is well. You will however see the servos orient themselves, had they been connected, they could get stressed, damaging the servos.
23. At this point they are “centered”.
24. Now attach the rods to the ball inks. Things should be connected on the inside since we mounted the ball links on the inside earlier. Make sure rods/arms are at a 90 degree angle.
25. Once rods are connected to ball links. I unplugged the Battery from B400.
26. Screw in the center screws onto each servo. Hold the servo horn so you don’t stress the servo when you tighten the screw. Make sure to get the screw started correctly you don’t want to damage the thread.

Reversing Swash Mix Values on the DX6i (I assume you are also swapping out the tail servo)
27. Via the setup menu, go to swash mix and change anything with a + to a – AND switch anything with a – to a +. Set any R to N and N to R. The goal: mirror any default settings.
a. Original settings: Thro – N , ELEV – N, Gyro – N, AILE – R, Rudd – R, Pitch –N
b. New settings: Thro – N, ELEV – R, Gyro – N, AILE – N, Rudd - R, Pitch - R
28. Leave menu for swash mix settings.
29. Go to “Reverse” menu option. Reverse Aileron
30. Exit and turn off (saving settings) radio.
31. Switch of throttle hold switch set earlier (radio beeps if set while turning on)
32. On the Gyro, find the two small switches.
a. Set the REVERSE switch to ON
b. Set to 2nd switch to DIGITAL (JR servos are digital).

Removal and Installation of the DS3400G Gyro (tail) Servo
The DS3400G is a bit larger than the stock. It was harder to install than the other three because the potential for binding exists. If you don’t have this mounted correctly, and if you don’t use the right servo horn, you will have a binding issue. This servo is powerful and has lots of travel; you therefore want it to move freely to avoid damage.
Take a look at the thread I posted and specifically to the response by totsandman (picture): .
Notice the following:
a. The servo is mounted using the 1st and last holes on both the frame and boom servo mount as noted. Illustrated better in the response by totsandman.
b. The boom servos mount (once you remove the stock servo), can open up allowing removal from the tail boom once screws are removed. I then reversed it so the screws go in from the right side of the heli if looking from the tail forward. I used the grommets and the 4 screws (frame and boom mount).
c. The ball link is on the outside
d. The servo horns used were the smallest (4-way) in the JR pack. They only have one hole per arm. I cut all but 1, but don’t do that yet. Read on 1st.
1. Disconnect ball link from tail servo
2. Unplug cable from receiver
3. Remove mounting screws and remove stock tail servo
4. Remove and reverse tail boom mount as mentioned in step b above.
5. Mount new servo using grommets and screws (4 in total). As mentioned above. There are three mounting holes in the frame and boom support. Skip the middle holes.
6. Verify the servo is nice and straight as shown in the picture at the provided URL.
7. Cut all but one servo horn, and then connect the ball link (facing outward) to the servo horn.
8. Click the servo horn ball link to the tail rod (not onto the servo yet)
a. Make sure radio sticks are centered.
b. Make sure you disconnected the Heli motor!
c. Make sure all servo horns remain disconnected, all ball links disconnected.
d. Turn the DX6i on.
e. Set throttle hold.
f. Make sure trims are all centered
g. Connect the Battery on the B400. Of course do not expect the usual beep indicating all is well. You will however see the servos orient themselves, had they been connected, they could get stressed, damaging the servos.
9. At this point they will “center”.
a. Note: This procedure is best presented in a video by sokal11 available here on youtube: starting a 3:35 into the video. Idea is let the servo orient to center then connect the servo horn to the servo, should be at a good 90 degree angle.
10. Verify that when you move stick the rod is not binding against servo or servo horn. It should move forward and backward freely.
11. Turn B400 off
12. Screw in the center servo horn screw to the servo. Hold onto horn while tightening.
13. Install new tie wraps (I went with black for the AR6100e and ESC at the frame) and smaller wraps for the servo cables.

Verify ALL Controls Working Properly
1. Reference the B400 manual section detailing control input and associated movement on the B400. Make sure everything moves in the proper direction as documented.

Note: I had to run through the procedure for leveling the swash, washout and flybar cage. There is good information in this forum on doing that. SkunkyMagoo has a great picture describing this.You can find it here:

I welcome any additions or corrections that will help anyone attempting this procedure. I want to thank those I mentioned in this entry, for educating me along the way.

Good luck with the install!
RoyRC is offline        Reply With Quote Quick reply to this message
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Old 09-13-2008, 06:46 PM   #2 (permalink)
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looks good sometimes rge rev menu will be diffrent for some like mine was like u posted and i cleared my remote and now the aile and elev servos were opposit of what they were (ooood?) but just make sure your swash plat coorisponds to movement inputed.
B400 DS285/3400G/401/-8/40Aesc/sonicCNC/CNCframe
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sokal is offline        Reply With Quote Quick reply to this message

ds3400g ds285

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