Tamiya DMD/MFU Recoil not switching off

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Alan123
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Tamiya DMD/MFU Recoil not switching off

Post by Alan123 »

Hello,

I have been experimenting with my DMD/MFU unit and have made a mistake that has resulted in the recoil no longer shutting off after one shot and the MFU showing a red light to indicate a problem.

It is not the micro switch etc, it is a diode or something that has blown in the MFU as a result of the recoil plug wiring being wrong (from experimenting, I was trying to get a modified HL recoil unit to work with my Tamiya MFU for my KV1 project) and has burnt out a component.

I have read somewhere that the blown component is quick and easy to replace however I cannot find where I read that at RCU and wondered if anyone here knew what it was I need to order and do.

This is the second time I have made this mistake and damaged an MFU.

Hope you can help.

Thanks.

Alan
Last edited by Alan123 on Fri Jul 30, 2010 10:24 pm, edited 1 time in total.
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Pcomm1
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Re: Tamiya DMD/MFU Recoil not swithing off

Post by Pcomm1 »

Tamiya will generally replace a faulty DMD Unit for free with no questions asked, visit: http://www.tamiya.de/de/service.htm" onclick="window.open(this.href);return false;

But also run the DMD test functions and re-boot the units per the DMD instructions first.
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Alan123
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Re: Tamiya DMD/MFU Recoil not swithing off

Post by Alan123 »

http://www.rc-panzerketten-forum.com/wb ... r=0&page=4" onclick="window.open(this.href);return false;

This is where I saw the self help on what to replace, sadly it related to a leo2 DMD and not a Tiger DMD so does not help me really. I am sure the principle is the same, and I did look at all the resistors to see if there were any burnt looking ones but did not find any.

This is absolutely the last time I go it alone on a HL RRZ connected to a Tamiya DMD/MFU experiment, will leave it to people who know what they are doing, like Grompix for instance.

Good advice PComm1 however no amount of rebooting etc will reinstate a burnt out resistor and the Tamiya de people wanted 200euros last time I made this mistake and asked them for help.

I guess I will be building a Tamiya recoil unit into my KV1 now after all.

AL
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grompix
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Re: Tamiya DMD/MFU Recoil not switching off

Post by grompix »

Hi Alan
No good news I'm afraid (from me anyway - someone else may have a solution). The same thing happened to one of the lads up here (Edelweiss3945) with his Tiger1 after trying to fit an Asiatam recoil unit. I had a good look at the PCB but coudn't see any burned or damaged components. I tried a pucker Tam recoil on it and even that refused to work.Tamiya didn't want to know (didn't even reply to his e-mails). So now he has a MFU with no recoil. Everything else works OK on it though, so its not a total write-off. Maybe the guy that wrote the article on Panzerketten may know something.
Sorry, wish I had some better news.
Chris
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Alan123
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Re: Tamiya DMD/MFU Recoil not switching off

Post by Alan123 »

Dear Chris,
I have posted a post in the Panzerketten forum but I am guessing his knowledge is based on necessity and is restricted to his Leo2 DMD, no one wants to have to learn this stuff as it means one has a damage modul.

Now my MFU is only fit for a Sturmtiger that does not need a recoil, which is where it will be going, along with my DMD that does not have a working turret turn function. There is a use for everything.

I had another look at my setup this morning, in the fresh light of day, and compared my wiring to that of a Tamiya recoil unit. It looks to me as though I needed to have soldered the white and green wires on the other way and it might have worked ok, that being said I am not going to try it as one damaged MFU is more than enough for me.

One thought though, for that damaged Tiger MFU you mention: Is that if the problem is like mine, that the recoil now simply repeats itself for 30 seconds and then stops, and sometimes not in the right position, because the shut off is damaged in the MFU. It is possible to put a resistor in the line so that the recoil only has enough power for one revolution, it is what one had to do with one of the early Elmod setups. It worked well with Elmod and the same principle should apply for a damaged Tamiya MFU too. I might give that ago one day too, but at the moment I am a bit peeved.

Alan.
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Re: Tamiya DMD/MFU Recoil not switching off

Post by grompix »

Hi Alan
I know how you feel mate. It's rough when something like that happens (and Tamiya MFU/DMD's aint cheap). It certainly might be possible to rig a microswitch so that it cuts the power after one cycle. I'm thinking of the limit switches that you can add to the Tamiya gun elevation motor to stop it moving after it reaches the limits of elevation and depression. Maybe you could rig something like that for a gun recoil but I'm not sure. I think you would still need two microswitches - one pwering the recoil motor bacwards and then another to reverse the current flow to return the gun to the battery position. You'd need some diodes as well. I've attached a circuit diagram in case it might help.
Cheers
Chris
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Limit Switch Diagram.jpg
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Re: Tamiya DMD/MFU Recoil not switching off

Post by 971wright »

Hi I think the problem is the signal isnt shuting off so it keeps cycling,the good news is there could be a fix ,using a splitter(conect two wires to the function for firing and elevation) from the reciever,using two of the three wires positive and negative (the way they work three wires one neg and two postive for directional control of a motor) sort out which positive is the one for up fire main gun. Use this to start the cycle and wire it similar to the limit switch diagram Chris has posted,You may have to add two extra power+/- leads to keep it running, have it in my mind but getting down on here is hard to explain.Basicly you arnt using the MF unit to control the recoil,but it is still wired to the receiver so it gives you flash and sound.

regards pete
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Re: Tamiya DMD/MFU Recoil not switching off

Post by grompix »

That's interesting Pete. Here's a guy that's done it with an external PCB.

http://www.youtube.com/watch?v=kfBRioXi6sE" onclick="window.open(this.href);return false;

...and this guy (TankHobby) has a clip of a servo recoil that he is using for his 21C Pak40:-

http://www.youtube.com/watch?v=vQze4wkDeYg" onclick="window.open(this.href);return false;

Might be worth getting in touch with him.

Chris
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Re: Tamiya DMD/MFU Recoil not switching off

Post by 971wright »

Hi Chris Thats the idea by taking the signal from the reciever the recoil is just a motor same as a servo might have to fit microswitch to stop it .by using the splitter it will still go through the MF unit to give flash and sound.Im sure its possible
Need an electromagian to draw a diagram and post it.

regards pete
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Re: Tamiya DMD/MFU Recoil not switching off

Post by AVATT »

Hello all:

Anybody still experiencing these recoil problems or to Alan do you still have these units because I just experienced the same problems, testing 2 MFUs and 2 recoil units but found a significantly simpler fix.
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