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Old 12-18-2012, 10:38 AM   #1
johnbheli
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Default GY 401 in a ZHP + Spektrum DS-8 module

I've got a strange situation re a Futaba GY401 that I inherited with a second-hand model. At first I thought that it was a Hong Kong / Chinese fake as these are quite well documented with "silver" plug contacts instead of "gold"; Phillips screws instead of "Tri-Wing" screws holding the case together, different print fonts on the gyro case, and a large rusty nut inside to give the correct weight! It does seem genuine, having passed all the above tests! It works fine on the bench - apparently switching modes correctly - but the LED stays lit - see below.

The reason for my concern is that the red status LED does not go out when switching from AVCS to normal rate mode, whereas it does on all of my other 401's. I've bench tested it on a full Futaba set up, on 35MHz and it behaves normally?.

I'm using my trusty Futaba ZHP + Spektrum DS-8 module driving a Spektrum AR6255 Rx which binds fine.

I've tried most if not all combinations of ATV on the gyro channel; gyro function on the Tx enabled and inhibited, channels reversed, etc, etc.There is no way I can make the LED go out when the gyro is installed in this model.

Power supply is via the internal BEC in the Castle Creations Pheonix 60 ESC with the volts supplied by 3S LiPo.

Thoughts, comments please.

Many thanks

John B
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Old 12-19-2012, 08:31 AM   #2
marc8090
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Even though the led stays on, does it switch to normal mode? In heading hold if you turn the heli on the bench the servo will move and not return to center. In normal, if you move the heli, the servo will move if there is enough gain but every time you stop the movement the servo will return to the same center position like any other channel. So what does it do?
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Old 12-20-2012, 09:57 AM   #3
johnbheli
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Hi the mode (gear) switch appears to function correctly - the servo doing as you describe

Many thanks

John B
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Old 12-20-2012, 10:10 AM   #4
marc8090
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Very good. I see no reason to fly the 401 in normal mode, but if you do choose to do so remember it must boot up in heading hold.
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Old 12-24-2012, 04:22 AM   #5
johnbheli
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Problem solved - I'm embarrassed by what I've found - although in my defence....read on.

Essentially the problem was caused by the ESC supplying the full 3S LiPo voltage to the Rx and hence the gyro!
I'm surprised it didn't kill everything - but all items appear to have survived.


During testing - after I had apparently burnt out two old servos(!!); I found 12v + at the ESC output to the Rx! I should have tested the output voltage first!!

When I acquired the model there was a Hobby Wing UBEC fitted - but I removed it because all indications from the Castle Phoenix 60 instructions were that when using a 3S set up the integral BEC was fine. I'm now thinking that I confused the ability to use a BEC when a 3S LiPo was used with the fact it has an integral BEC. The instructions talk about removing the positive wire from the throttle lead to the Rx - but nowhere does it state that separate BEC must be installed. I now believe that there isn't a BEC integral with the ESC device?

Thank you for your help and advice.

John B
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