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Testing a 27 mhz remote


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bidgeeman



Joined: 06 Feb 2012
Posts: 5
Location: Coffs Harbour


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Testing a 27 mhz remote

Hi.
Just wondering if anyone could help me out. I have a remote cointrole K9 from doctor who. It's a bit of a collectors item now and I just bought it 2nd hand. For some reason the K9 robot is not responding to the remote or the remote is not transmitting. I don't know which is which. I also have no experience in RC but was wondering if there was a way to test if the remote was transmitting to find out where the problem is.

Checked the control out and all the wires are clean and connected.

Any help would be greatly appreciated.

Thanks
Bidge

Post Mon Feb 06, 2012 3:58 pm 
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dyrodium
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Joined: 24 Aug 2004
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Location: Sydney


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Hey there,

27mhz AM systems require a crystal to tune the transmitter into the reciever, they're little removable silver things with two prongs. If you can locate them they have to have exactly the same number on them to work. They can also break so might need replacing. Do you get any kind of power light on the transmitter or reciever in the k9? A photo would be really helpful here!

In this day and age replacing the controller with a newer 2.4ghz system would be a great idea, it will help prevent your machine twitching and running away due to loss of signal and give much smoother control. Smile

Post Mon Feb 06, 2012 4:43 pm 
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bidgeeman



Joined: 06 Feb 2012
Posts: 5
Location: Coffs Harbour


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Hi. Many thanks for your reply.
Here are two images of the actual unit.

(Images removed issue solved)

I did notice a silver oblong looking thing under the circuit board on the opposite side as the general components when I pulled it apart. Also there apears to be no light on the rc unit at all.....the buttons on the front look like lights but are holes where the buttons should go. When I had the unit pulled apart my wife fiddled with the plastic buttons that were moulded onto a stem and she broke off the last button so I left it out till I fix it. The buttons can be depressed using a p[encil poking down through the hole.


Cheers
Bidge


Last edited by bidgeeman on Mon Feb 13, 2012 6:57 pm; edited 2 times in total

Post Mon Feb 06, 2012 5:14 pm 
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seanet1310



Joined: 08 Nov 2006
Posts: 1265
Location: Adelaide


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This is a put in battery and go kinda devence so it is unlikely the crystal will be highly user serviceable (under an easy to undo panel or even just a slot). Chances are the crystal will be under the casing somewhere on the PCB. May or may not be removable.

If you have an oscilloscope you could check signals to the antenna and on the dogs side.

Any chance you have photos of it pulled apart ? Would be far more helpful then generic grey case
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Post Mon Feb 06, 2012 5:57 pm 
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bidgeeman



Joined: 06 Feb 2012
Posts: 5
Location: Coffs Harbour


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Hi. I just pulled his remote unit apart again and took these pics for you.

(Images removed issue solved)

I think the silver thing at the bottom of the board is the crystal you are talking about. It's a bit hard to get the board off it's mounts as the wires are so short I would have to cut them to flip the unit over and I am not much of a solderer Wink

Hope you can help.
Cheers
Bidge


Last edited by bidgeeman on Mon Feb 13, 2012 6:57 pm; edited 1 time in total

Post Mon Feb 06, 2012 7:12 pm 
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marto
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Hmmm yeh it looks to be a self contained unit with a single IC under your black goop and while the crystal may be damaged its hard to tell unless you give it to someone who can test it properly.

Did you want to maintain the original electronics as if you want I could probably assist in reverse engineering the controls and replacing it with a modern Tx/Rx combo. Although this may require a complete rewiring of the K9 unit as well.
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Post Mon Feb 06, 2012 8:21 pm 
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seanet1310



Joined: 08 Nov 2006
Posts: 1265
Location: Adelaide


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Yea, Like steve said that looks to be the crystal and everything else of importance for processing is in an Integrated Circuit protected by the black blob.

Are you sure it is the TX at fault and not the RX in the k9? If you are confident at soldering and can find a crystal with the exact frequency you could replace it and see if that fixes the problem
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Post Tue Feb 07, 2012 4:51 pm 
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bidgeeman



Joined: 06 Feb 2012
Posts: 5
Location: Coffs Harbour


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I have another working remote arriving at the end of the week so will try that. Also found out that the ariel for the unit is in the tail and if the wire comes off (from being twisted as it's rubber) the wire can come off the board in the unit.

Thanks for the responses
fingers crossed.

Cheers
Bidge

Post Wed Feb 08, 2012 7:00 pm 
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DumHed
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quote:
Originally posted by marto:
Although this may require a complete rewiring of the K9 unit as well.


I don't think you can do that if you're not a timelord
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Post Wed Feb 08, 2012 8:36 pm 
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marto
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Give me another year and then you can start referring to me as "The Doctor"
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Post Wed Feb 08, 2012 9:11 pm 
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Valen
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sound more like the master to me ;-P
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Post Fri Feb 10, 2012 9:19 am 
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bidgeeman



Joined: 06 Feb 2012
Posts: 5
Location: Coffs Harbour


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Hi All.
Just an update. New remote arrived today and the unit worked. It was the remote that was faulty.

Thanks again for all the replies.

Cheers
Bidge

Post Mon Feb 13, 2012 6:55 pm 
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marto
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Cheers. Good to see it all worked out.

Steve
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Post Tue Feb 14, 2012 12:42 pm 
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