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Mini CP Walkera Mini CP Helicopter Support


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Old 03-29-2012, 07:47 AM   #1
mescalinedream
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Default How to fix the coil on a Minicp RX(WOWS SILiCONE DOES NOT WoRK!)

Forgot to mention that this RX is from Wow hobbies with white silicone on it. The silicone does not help. Its soft and weak! Remove and glue it. I recommend white gorilla glue. IT says on the bottle "Dries White 2x Faster" Its strong, light and expands 10x so go light with it. i also use it for canopy cracks,boom cracks anything and everything. And if you havent yet, glue the black antennae wire down on he mini's board. It can and will short itself out onto something. dont let the end come in contact with anything. Glue the base of the battery cables too.



Recently a member on Rcgroups sent me his Minicp receiver for repair. He had broke the battery cables and coil from the RX. The coil is in the bottom right hand corner and it sticks up a little. Its common for it to break off (poor design on walkera's behalf) and then the rx will not power on. On his board there was a base of ceramic left over which needs to come off. I ground it down with a dremmel. This is what was left over:

That pic isnt mine.

I made the new coil with 8 inches of wire that was the same diameter of the minicp/genius red/clear tail wire. I just found out recently that a member on here has used headphone wire. Much smaller diameter! cleaner install too! Here is his post: http://www.rcgroups.com/forums/showp...postcount=2735 I coiled the wire around a small drill bit and soldered one end to one solder point on the left of the pic. I soldered the other end to the solder pad on the right in the pic. i then tested to see if it worked and it did . Then I glued it to the board with 2x white gorilla glue. You only need a tiny bit cause it expands. I use that for everything, cracks in the canopy will never crack again with that stuff.
I am sure the wire could be both thinner and shorter. I didnt want to experiment with his board though. MX48 over at rcgroups was the first to try the wire for the coil. So I just used what he did. Here is what the finished board looks like and the of it working.

If you are scared to do the repair yourself then I can do it for a 5 dollar plus shipping fee. I also fix battery cables too for the same price.

Last edited by mescalinedream; 04-02-2012 at 10:18 AM..
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Old 03-30-2012, 04:54 PM   #2
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Great Job!
Does anyone know what that little coil actually does? There are only two leads so it cant be a voltage transformer.?.?.?
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Old 03-30-2012, 05:14 PM   #3
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The telemetry may not work after this repair. i812 said this at regroups:

I also read the earlier post(s) that stated the Inductor coil may be used as a "choke" to help eliminate current spikes. That may be true. If so, as the person posted earlier, everything would probably work well enough if the Inductor coil was replaced with a short straight piece of wire. I think most of the times, chokes are used as a precautionary device to help eliminate occasional "noise", just in "case", but may not be absolutely necessary.

However, if the Inductor coil is used with a Capacitor, then it might be used as a tuned circuit for an oscillator. If so, replacing the Inductor coil with a straight wire will stop the oscillator circuit, and no Telemetry data will be transmitted to the TX.
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Old 03-30-2012, 06:37 PM   #4
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The coil is being used as a choke for the 8205A (Dual FET wired in parallel) that drives the tail motor, so any problems with that choke would probably affect the tail motor only. Definitely not part of a tuned circuit. I too would think you could just add a piece of wire to jump across so it boots up. I wouldn't recommend this though as it could either affect tail performance, or save the FET if your tail motor gets tied up in the grass etc. There is a good reason the engineer wanted it there. If it was going to work the same and be reliable with just a jumper wire then trust me, they wouldn't go through the hassle of using that inductor. I may be getting my hands on a scrap Devo receiver. If I can't fix it, I can disconnect a lead and measure the inductance and resistance and recommend a replacement part you could purchase. They are available OTS at most places like DigiKey so I'm sure we could cross it to the correct part if Walkera won't tell you the part number or value.
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Old 03-30-2012, 07:31 PM   #5
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If it was only for the tail then why would the board not power on or did they say it wouldnt bind without the coil? Also the original guy who used the same fix I did has repeatedly flown his heli with no problems.
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Old 03-30-2012, 08:37 PM   #6
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Sorry about the confusion. Since they never setup a separate thread for the mini, while a lot of the info from the standard GCP is similar for the mini, in this case after taking a closer look at your photos I realize that the coil on the bottom of the GCP that has been known to come loose is used differently than what you are referring to on the mini.
Since I don't have a mini, I'll step aside on this one. Sorry for the confusion.
My bad.
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Old 03-30-2012, 09:14 PM   #7
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The newest arrivals of the Mini CP has silicone (white) on the coil to prevent damage. This is how my mini cp arrived today from WOW Hobbies.
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Old 03-31-2012, 07:24 AM   #8
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Silicone does not hold! Thats what i just fixed!!! That stuff is really weak and soft. Take that off and gorilla glue it. The white kind it says dries 2x faster on the bottle. I use it for the battery cables, the black antenna that can short itself out on anything it touches and the coil. I also use it on cracks in the canopy. And I took the rubber cap off the tail motor and gorilla glued the tail motor wires to save on weight. Cracks in the boom I also repaired with it. Love it, also its lighter then hot glue! Go light on whatever you glue. It will expand to 10 times the size!
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Old 03-31-2012, 07:58 AM   #9
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Quote:
Originally Posted by Intheway View Post
Sorry about the confusion. Since they never setup a separate thread for the mini, while a lot of the info from the standard GCP is similar for the mini, in this case after taking a closer look at your photos I realize that the coil on the bottom of the GCP that has been known to come loose is used differently than what you are referring to on the mini.
Since I don't have a mini, I'll step aside on this one. Sorry for the confusion.
My bad.

I put in a request today to one of the moderators on this site to have a separate thread for the Mini CP.
He got back to me and said that he has forwarded the request.


Tom
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Old 03-31-2012, 08:07 AM   #10
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Thanks for posting this. This is good to know.
I have the white silicone on my coil also.
The white gorilla glue sounds pretty good.
I take it that it is flexible like hot glue.
Will have to try it on a canopy also.


Tom
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Old 03-31-2012, 04:26 PM   #11
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Default New Mini CP Sub-Forum

Quote:
Originally Posted by CX2Pilot View Post
I put in a request today to one of the moderators on this site to have a separate thread for the Mini CP.
He got back to me and said that he has forwarded the request.


Tom


Quote:
Originally Posted by Intheway View Post
Sorry about the confusion. Since they never setup a separate thread for the mini, while a lot of the info from the standard GCP is similar for the mini, in this case after taking a closer look at your photos I realize that the coil on the bottom of the GCP that has been known to come loose is used differently than what you are referring to on the mini.
Since I don't have a mini, I'll step aside on this one. Sorry for the confusion.
My bad.


My request to have to separate thread for the Mini CP has been approved!
It is now in the Walkera Helicopters Sub-Forums section.

Thanks Helifreak!


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Old 03-31-2012, 04:52 PM   #12
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Quote:
Originally Posted by CX2Pilot View Post
Thanks Helifreak!
Agreed!
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Old 03-31-2012, 06:30 PM   #13
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Are the mini posts in the genius thread going to be switched over to the mini thread? I think this post is important.
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Old 03-31-2012, 08:43 PM   #14
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Yes they will.
I am helping out with the moving of the posts.
I have you on the list of posts to move over to the Mini CP section.

Tom
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Old 03-31-2012, 09:11 PM   #15
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CX2Pilot rules.
Thanks for taking the initiative, and 'helping with the move'. There are certainly enough differences to warrant it having its own place.
Thanks HF for all you have enabled here.
Hope it works for everyone to have it this way.
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Old 04-01-2012, 02:44 AM   #16
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All I can say is that the silicone applied on my board was well done. The one way I would see the silicone fail(if applied properly) is with a hard crash or with a poorly prepped surface that it would compromise adherence. Silicones are used in high quality equipment such as amps, circuit boards, manufacturing equipment to protect the circuitry from falling apart with in its solder points (be it thru board or surface mount) in high vibration environments when power is going through it.

Now, I agree that gorilla may hold up better in a crash, but the right type of hit will dislodge the coil. Thats the nature of the beast. I'm just stating facts and not trying to start an argument . I applaud you for coming out with a good fix on the cp mini's short comings and sharing your experience with me and others. Thank you!

Best regards,
Rupert
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Old 04-01-2012, 06:45 AM   #17
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That is your opinion Rupert. I think almost everyone still crashes now and then. Would you rather have the coil come off with soft silicone? Or not budge with glue? That silicone is made for vibration like you said, not a crash. An amplifier is not going to crash +10 miles an hour and still work. My mini has though! Since this is a walkera fix, do you actually believe it would work? Have you seen their fix for the servo gear stripping problem? They made the cord longer on the servo and added dielectric grease to the solder points. That has nothing to do with a gear stripping. Just like silicone has nothing to do with saving the coil.
Maybe the silicone is there for those who had their coil fall off in the box in shipping. In that case it would work for that, but will not work in a crash.
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Old 04-02-2012, 10:48 AM   #18
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I used black silicone and made sure I pulled the bead around the corner of the pcb. It seems to be working fine.

Also, trimming back the leading edge of the canopy a tiny bit will keep it from tearing across the coil when it twists up.
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Old 04-02-2012, 11:02 AM   #19
Heli-opolis
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Just to piss MescalineDream off, I'm going to try my favorite, Loctite Epoxy Putty.

Good for what ails you and if you ain't ailin', you soon will be.

Don't worry MD, I'm just yankin' your chain.

<-- Makes note to self, "Self, pick up bottle of Gorilla 2X Whitener and breath freshener glue." Or something like that.

Still, the chain yankin' thingy, nothing to get twisted about. Unless you want to, and then we can 'dance'.
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Old 04-02-2012, 04:01 PM   #20
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Funny man are we? hehe I love gorilla glue. I dont like the smell of epoxy and I always get some on me. If i get gorilla glue on me I wipe it off since it takes a little while to set.

Are all silicones/glues non-conductive? I wouldnt want someone's board to short out if they used something they shouldnt. I had even seen copper flaked epoxy. Some newbies might use it and fry their boards.

Also I changed the first post. It seems that just about any wire will do for this fix. A member at rcgroups tried the wire inside a headphone ear piece. Very thin wire. Here is his post http://www.rcgroups.com/forums/showp...postcount=2735 I really wish I would have known about that thinner wire for Benboys' RX. I didnt want to experiment though with someone's board. I dont have the money for a 70$ replacement!
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