Taranis not powering back on

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Badlands
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Taranis not powering back on

Post by Badlands »

This is a weird one...
My Taranis will not power on after a power off & drains the battery over-night.

The internal transmitter module appears to stay on after a power off & drains the battery.
If I remove the battery & re-connect all is good, I then power on - all is good & useable, if I power off - it powers down but will not power back up again until I remove the battery.

On normal power-up the Taranis draws approx 160mA, if I power down it draws approx 130mA indicating the internal transmitter is still active.
To prove this if I set a motor off failsafe on a quad then power down the quad doesn't go into failsafe.


Any ideas?

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MikeB
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Re: Taranis not powering back on

Post by MikeB »

For a standard Taranis (not plus):
There is a transistor switch that controls the power to the internal module. On the back board, it uses components R9, R12, R13, R14, Q3 and Q1.
Q3 is a N Mosfet, Q1 is a P mosfet and switches the power. The resistors control the switching.
When power is off, R12 and R13 should both be a ground at both ends, and Q3 off. R9 and R14 should be at battery voltage with Q1 off.

Mike.
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Badlands
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Re: Taranis not powering back on

Post by Badlands »

Thanks for the reply Mike,
My unit is a Taranis Plus (so sorry I didn't clarify that)
When I power off, the LCD display disappears as normal but the internal module is still powered, then the unit refuses to power back on until I remove the battery.

Things I have tried -
Reflowed main micro
Reflashed f/ware
Factory reset
Swapped micro SD card.

Do you know the component's that control the internal module on the plus model?
Would these being faulty stop the unit from powering back up again?

Thanks,

-Martin
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MikeB
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Re: Taranis not powering back on

Post by MikeB »

Backboard: Q5 = N mosfet, Q6 = P mosfet, resistors are R16 and R17 on Q5 and R21 and R18 on Q6.
It may be it hasn't fully powered off.

Mike.
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Badlands
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Re: Taranis not powering back on

Post by Badlands »

MikeB wrote: Fri Apr 14, 2017 11:10 pm
It may be it hasn't fully powered off.

Mike.
So that would suggest a main board problem? I kind of agree.
I will do some testing around those components you listed.

Cheers!

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MikeB
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Re: Taranis not powering back on

Post by MikeB »

The main board soft power switch is:
Hardware power switch pulls D1 and D2 low, D2 pulls logic signal to CPU low, pullup is R57 on this.
D1 turns on Q3 to enable power, via R55 and R54.
Q2 also pulls R55 low, controlled by the CPU via R52 and R53.
When you switch off, R57 should pull the logic signal high, so the CPU should then drive R52 low causing R55 to be pulled high by R54, turning Q3 off.

Mike.
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BenJaminFPV
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Re: Taranis not powering back on

Post by BenJaminFPV »

Man, I have this exact problem with my X9d+.

Radio turns on, but only if switch is on and a battery is then plugged in.

After switching radio off, it will not switch back on.

The transmitter module does not power off after switching the radio off.

If the radio is switched off and a battery is then plugged in, it will not turn on.

All firmware and SD files have been updated. This radio was new in box, with the stickers and peel plastics still attached. It’s as mint as they get!

Any advice on which resistor or transistor to replace? I’m not sure which type goes where, but I’m willing to do anything to get this X9d+ working right.

Mike, if you’re reading this, thanks for being so helpful to so many here! Reading your posts has gotten me closer to getting this fixed than I thought I’d get.

I attached pics of the area of the main board in question. The soldering looks fine to my untrained eye.

Cheers!
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MikeB
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Re: Taranis not powering back on

Post by MikeB »

Have you just bought this new? If so, ideally you just contact the seller and get a replacement.

When you switch off, does it go off immediately or does it take some time after you move the switch to off?

Not sure I like the look of the soldering on D1, at the end where the "D1" text is.
If you have a voltmeter, try measuring the voltage on the pin of Q2 where the "Q2" text is (this connects to D1). When the power switch is on, this should show about 0.6V.

Mike
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BenJaminFPV
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Re: Taranis not powering back on

Post by BenJaminFPV »

Mike, thank you for the quick reply! I’m determined to get this fixed as I got a good deal on it.

I’ll see what the voltage is on the pin of Q2, resolder D1 and keep you posted.
BenJaminFPV
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Re: Taranis not powering back on

Post by BenJaminFPV »

Mike! You’re the man! I redid the soldering on D1 and that did the trick. It’s been power cycling correctly for a few days now. Thank you so much for the help! Feels way better conquering little problems like this and learning than just getting a replacement to me.

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