3 in 1 Meltdown

[MAXXED]

Just when everything seems fine, there's always something about to happen. :roll:
I call it the "what next?" syndrome. :lol:
While testing my Blade in my yard the other day and making some adjustments, the tail rotor started to behave erratically.
I couldn't keep the tail in control no matter what I tried.
The first thing that I thought of was a weak battery.
After an emergency landing from not being able to control the tail, the tail rotor motors went berserk and ran at full throttle.
I couldn't shut it down from the transmitter which didn't respond at all, so I disconnected the battery.
Put in on my shop bench, powered it up, and the tail motors went to full throttle again, with no input from the radio.
Shut it down, and came back a few hours later, and there is no power output at all to the tail rotor motors.
After an autopsy of my 4 in 1, here's what I found:

http://i20.photobucket.com/albums/b239/airshop/3in1board.jpg

One of the chips right behind the proportional trim pot literally exploded and blew a hole in it. :shock:
You can see the round hole right through it, like a miniature bullet hole.
This probably explains the erratic tail behavior before the meltdown.
I've heard of similar, more spectacular 4 in 1 failures, such as units actually catching on fire.
Is this just normal wear and tear or are these chips really poorly toleranced surplus chips?
I have a new eSky 4 in 1 on the way, but if this is a common trend, it would be cheaper to upgrade to separates than to constantly replace these 4 in 1's.
I've had my Blade for about 10 months, which means replacing a 4 in 1 once a year or less, at this rate.

[swatson144]

Probably the tail motor was going out, while it acted up. It finaly went out shorting out and burning the FET.

The best way to protect against this happening again is to put a 2A fuse inline with the tail and a 7A inline the main.

Yours looks repairable. Most of the ones I have tried to fix have had burned traces. It appears the IFR 7456 is not the correct replacement and doesn't switch fast enough. I'll give the IRF7413 a try. I had forgotten this project and still need to get an order off to digi key.

Steve

[eddiemoth]

One of the chips right behind the proportional trim pot literally exploded and blew a hole in it. :shock:
You can see the round hole right through it, like a miniature bullet hole.
This probably explains the erratic tail behavior before the meltdown.
I've heard of similar, more spectacular 4 in 1 failures, such as units actually catching on fire.

You have the two tail motor system right? If you have spared tail motors, try to see if the problem is resolved assuming the whole may not be touching the programming of the chip unless if you see a trace of recent burning. It might be there from the factory.

I used to work for an electronic manufacturing company in California. I would say that the circuit board used in Blade's 4 in 1 is very low in quality - I hear sorts of bad thing about it - including cold solder, the chip dropped off, burning chip, etc. A circuit board must pass the functional test (if not - it has to be fixed there before going to the next step) and then put in a burning chamber to go through extreme temperature (cold and hot) cycles at least 24 hours, then must pass ICT test and pass a couple layers of QA and QC before shipping. They should have cautch most of the problems if they did all these things. Some of these circuit boards now are manufactured outside of the Country such as China, Thailand, etc. for cheap labor. So..............

One time when I was testing my tail motor (not even flying), the 4 in 1 was smoked with no reason. At the time, I called HH. They had me send it in and replaced the new one for me. Replace the tail motors and it is still the same, it must be something wrong with the unit. Try to call them - they might either fix it for you or give you a new one. Or you'll know when you get your esky unit. I am not familar witht seperate boards but if these boards are made with low standard quality, then it would be unpredictable as well.

[swatson144]

Nope that is the tail FET and it is toast. I tried the IRF 7456 16A as a repair but the motor just turns slowly so I'm waiting to get an order in for some 13a IRF7413 FETs they are only about 1.5$ each. I still have 8 of the 7456 which some people are using as an upgrade to the picollo boards.

My friend has 2 of the 4n1s burned. If I had a hot air rework station I could probably make 1 from 2 but with tools at hand the removal is a detructive process.

Those chips have no internal protection and any draw much over rating and they fail, sometimes spectacularly. Really as little as just stalling the motor.

Steve

[MAXXED]

Thanks for the info guys.
I'm running a dual tail motor setup, and the tail motors are still working fine after testing them, but the 3 in 1 is cooked.
The main motor esc still works, but the tail motor esc is dead.
As I suspected from your experiences, these are low quality components, and I guess we have to live with them, or invest in some better separate components. :roll:
But for what it's worth, the Blade CP is hard to beat at it's entry level price point. :)
I guess I'll start collecting some better electronics for it.

[swatson144]

Sounds like decision time for sure.

If you just want to get it back in the air with an HH gyro. You can use a servo extension to seperate the 2 cards (running between the throttle pins) and plug the gyro into the rudder chan on the back. Use HS tube on both cards. Then all you need is a decent cheap ESC. I use these on my tails. http://www.bphobbies.com/view.asp?id=V533528&pid=U616904 so you'd be back in the air for about the same price as a new 4n1 with HH gyro :-) with about a 20g weight penalty :-( . You'd be pretty well positioned to go BL main from there.

If you want to keep it all in the case you can cut the trace going to the signal on the battery pins (unused pins on the front), and green wire in a jumper from the rudder pins on the back signal to signal. Probably a good idea to cut the legs off the burned FET also.


Don't try to do this with a rate Gyro as you are bypassing the onboard mixes. You'd need a TX that does REVO. If you have a TX that does revo it's probably time to consider a new better airframe to put the money in.

From there it just starts getting scary cost wise, and a slippery slope of upgrades. You soon wind up with a lot of money (too much IMO) in an entry level heli. With no reasonable way to sell it. Perhaps just getting a new 4n1 is better all around and start building a more advanced heli.

You are right the entry price on these machines is hard to beat. I'd sure rent one for 20$ a month.

Steve