RunRyder - burnt 4-in-1!!

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e-E-Flite Blade CP CX 400-3D > burnt 4-in-1!!

murp
Senior Heliman
Location: Nova Scotia, Canada

I just lost my 4-in-1. My heli completely shut down in flight ! Luckily I was in a turn near ground so no crash damage. My main motor is toast, won't even turn. The main motor leads are melted, even the connector has melted and deformed. The 4-in-1 won't light any leds when I hook up a battery

Has anyone else lost a 4-in-1 like this?

03-12-2006 Over year old.

jughead
Heliman
Location: South Africa

Hi Murp

I had exactly the same thing happen to my honeybee cp2.
I was flying, and suddenly lost power, then loads of smoke, and a awful smell. MAin motor also wires also melted.
I also managed to fry one of my servos at the same time?

Aparently it has to do with a your speed controler in the 4in1 that dies, but I am not exactly sure. I think it is some kind od dead short.

I hope u get your heli in the air soon...

Why drink and drive when u can smoke and fly....

03-13-2006 Over year old.

murp
Senior Heliman
Location: Nova Scotia, Canada

Thanks for the feedback - I have been poking around my 4-in-1 and the FETs that drive the motors appear to have survived. The voltage regulators are fried though - I am going to get some new parts in and see if I can revive this puppy. I also noticed that the motor drive FETs are IRF7413 - I may replace these with higher rated parts, this would be a cheap way to upgrade the current rating of the ESC (I will try to get samples for free

-- Wish me luck!

03-13-2006 Over year old.

jughead
Heliman
Location: South Africa

let me know how it goes.

Why drink and drive when u can smoke and fly....

03-13-2006 Over year old.

murp
Senior Heliman
Location: Nova Scotia, Canada

Well the voltage regulators are goners - I removed the voltage regulators and powered the board up from a DC supply and the LEDs did their initization dance. So the controller IC is still alive. I have replacement parts en-route for the regulators. Hopefully this was all that got damaged, just in case I have replacement FETS on the way as well.

03-13-2006 Over year old.

jughead
Heliman
Location: South Africa

Hi Murp

I hope the 4in1 repair is coming along well.

I was wondering, in my limited understanding of electronics, is it not possable to install some kind of fuse btwn the batts, and the 4in1, so if somethong blows, it will be the fuse, and not the 4in1?

Why drink and drive when u can smoke and fly....

03-15-2006 Over year old.

BikeNBoatN
Veteran
Location: Santa Ana, CA USA

This thread talks about installing inline fuses to protect the 4in1 in case a motor stalls.

Brent.

03-15-2006 Over year old.

murp
Senior Heliman
Location: Nova Scotia, Canada

Yes, in general fuses could be installed. But the selection of a fuse that would blow quick enough is likely difficult (although I haven't attempted to do this). Fuses are generally used to protect the power source, i.e. the battery, and not so much the load.

The FETs are marginal at best as it is when you check the thermal ratings of the device. This is done to fit into the space and weight requirements that are available.

03-15-2006 Over year old.

BikeNBoatN
Veteran
Location: Santa Ana, CA USA

The author of the post I mentioned said he measured current draw on the motors to determine fuse size to use. He was originally doing this while stationed in Iraq, with limited access to spare parts. He did this to avoid having to wait for parts ordered from the States. He is quite confident his fuses protect the 4in1.

I have not tried putting fuses on my BCP as I have not burned up a 4in1 in 8 months. But reading his post, I have no reason to believe they would not work as he describes.

Brent.

03-16-2006 Over year old.

murp
Senior Heliman
Location: Nova Scotia, Canada

A well sized fuse will blow after the circuit has failed leading to a short circuit condition. So since the circuit is already damaged the fuse has not protected the circuit - rather it is there to stop any further damage and to ensure the power source is not held in a short-ciruit condition - thereby killing it as well. Fuses are slow devices compared to the time it takes for a semiconductor to fail - such as the mosfets that are used to drive the heli motors.

A fuse may be used to prevent further damage but more realistically, once the circuit fails the short will kill the device which will then remove the short circuit condition - the fuse will not even have gotten close to blowing before this happens.

03-16-2006 Over year old.

avator
Veteran
Location: New Jersey

I'm not sure if I agree with you Murp,

If a CP at full throttle with fresh batteries draws, say, 6.5amps and you use a 6 3/4 or 7amp fuse, I'm not so sure that you would fry the components in the 4in1 before the fuse blows. I haven't done any tests to prove this, however, I believe that fuses would provide some protection, at least, some of the time.
It stands to reason, that if a main motor starts to fail and begins to draw excessive current that the fuse would blow before the 4in1 components get permenantly damaged. I guess the trick would be to size the fuse between the maximum current a normally operating Blade draws and the point at which the 4in1 would be damaged. There has to be a range there, otherwise, everytime someone slamed the throttle up on the heli and got a current spike the 4in 1 would blow.
Just my thoughts on the subject.

03-16-2006 Over year old.

murp
Senior Heliman
Location: Nova Scotia, Canada

I have not looked into to this in great detail either - I probably will now that my interest is peaked.

I don't agree with your statment that throttling up quickly could cause a damaging current spike under my assessment. A current spike is not a high power (which = heat) event, it happens quickly and therefore would not raise the average temperature of the fet by very much if done occasionally during flight. If you constantly worked the throttle up and down you wcould raise the average current level, and who knows maybe get it above acceptable levels. Now if a dead short occurred because of a main motor failure this condition will persist until 1) the motor burns out and goes to an open circuit 2) the FET fries opening the circuit (which is the typical failure mode for a FET) or 3) the fuse blows opening the circuit. So it is a race - who dies first - in my experience the FET running near its limit is the winner - admittedly not always true - just my opinion.

Having said all that I do plan to investigate the fuse concept - I just lost a 4-in-1 so this is a sensitive issue for me

03-16-2006 Over year old.

murp
Senior Heliman
Location: Nova Scotia, Canada

Replaced Voltage regulators

Just an update - I just replaced the voltage regulators and the ESC has come back to life! The LEDs do the initialization blinking.

I plan to put it back together with the RX board and check that the servo and motor drives are all still working tonight. Will let you know how I make out.

Could be back in the air soon

03-17-2006 Over year old.

murp
Senior Heliman
Location: Nova Scotia, Canada

Oh and I forgot to mention that these are ~1.50CDN parts - you can get them from Digikey! You only need 2!

03-17-2006 Over year old.

murp
Senior Heliman
Location: Nova Scotia, Canada

I just put the 4-in-1 back together and it is working! I am about to go out and try hovering, just waiting for the battery to charge.

Anyone out there whose 4-in-1 mysteriously stopped working may want to look at this. If you had massives amount of smoke this may not fix your problem though. My symptoms were the main motor twitched a few times then the 4-in-1 just went dead. The motor leads were melted and the 4-in-1 did nothing when hooked to the battery. Anyhow, if any wants more details on this, let me know. Cheers.

03-18-2006 Over year old.

murp
Senior Heliman
Location: Nova Scotia, Canada

Well, just to finish this thread I successfully flew 3 batteries on the repaired 4-in-1 ... no problems to report.

03-18-2006 Over year old.

Deves
Heliman
Location: Anaheim CA.

Murp, I've been following your progress on this and I must say congratulations on repairing the 4in1. You are one lucky guy to be able to repair them yourself.

03-18-2006 Over year old.

jughead
Heliman
Location: South Africa

Well done mate.

You obviously know way way more about electronics than I do.

Check your post, I got to busted 4in1's on there way to u for repairs...... All the way from South Africa. lol

Why drink and drive when u can smoke and fly....

03-18-2006 Over year old.

avator
Veteran
Location: New Jersey

Hey Murp,

Yeah,
The current spike analogy maybe wasn't appropriate for this situation. I think you made the point that I was trying to make, it is a race and I can't help thinking that the fuse will win at least some of the time. At about $70usd for a burnt 4in1 lets hope it wins most of the time.
I think you've raised alot of interest in your repair of the 4in1. If you could post some pictures of the repair I think it would be appreciated by many, myself included.

03-18-2006 Over year old.

murp
Senior Heliman
Location: Nova Scotia, Canada

I would be happy to show some pictures - but first I am going to get some flying in. I will take it apart again to show the insides and which parts I replaced. Stay tuned...later murp

03-18-2006 Over year old.

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e-E-Flite Blade CP CX 400-3D > burnt 4-in-1!!

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