Taranis X9E, how know which component it is?

Cant get your radio to work? General Hardware issues?
Post Reply
DeWe
Posts: 1
Joined: Sat Feb 13, 2021 12:04 pm
Country: -

Taranis X9E, how know which component it is?

Post by DeWe » Sat Feb 13, 2021 12:19 pm

Uncomfortable the multiprotocol Modul has produced a short circuit and one wire of the FFC burned up (like a fuse). A new FFC cable is ordered and if no Modul is insert, I received the battery voltage at the expected pins. To go sure, that nothing else was happen, I have try to identify following component: EHGAG (U19 is printed on the PCB) . I didn't found anything about this one in the Internet. Maybe I search on wrong place, maybe with the wrong keyword) Uncomfortable the wire from the FFC (4) goes to this component and the biggest part current was going over this way.

Where I can find a Datasheet from this part?
20210213_112356.jpg
(1.58 MiB) Not downloaded yet


User avatar
MikeB
9x Developer
Posts: 17439
Joined: Tue Dec 27, 2011 1:24 pm
Country: -
Location: Poole, Dorset, UK

Re: Taranis X9E, how know which component it is?

Post by MikeB » Sat Feb 13, 2021 4:03 pm

U19 is a AM5521C and switches the power to the external module bay.

Mike
erskyTx/er9x developer
The difficult we do immediately,
The impossible takes a little longer!

User avatar
jhsa
Posts: 19428
Joined: Tue Dec 27, 2011 5:13 pm
Country: Germany

Re: Taranis X9E, how know which component it is?

Post by jhsa » Wed Feb 17, 2021 6:07 pm

Hmmm, that Mosfet seems to have a quite low Gate-Source maximum voltage, only 8V. I think I wouldn't use it to switch the module power in a radio. Does it have any protection on the gate? A zener diode for example?

João
My er9x/Ersky9x/eepskye Video Tutorials
https://www.youtube.com/playlist?list=PL5uJhoD7sAKidZmkhMpYpp_qcuIqJXhb9

Donate to Er9x/Ersky9x:
https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=YHX43JR3J7XGW

User avatar
MikeB
9x Developer
Posts: 17439
Joined: Tue Dec 27, 2011 1:24 pm
Country: -
Location: Poole, Dorset, UK

Re: Taranis X9E, how know which component it is?

Post by MikeB » Wed Feb 17, 2021 8:49 pm

I never looked at the datasheet for that part, the gate-source voltage for both MOSFETs in it are, indeed, 8V maximum.
The X9E uses 3 of these devices, one for the soft, main power switch and one each for the power to the internal and external modules.
Since the battery is an 8-cell NiMh, we have 9.6V (or more when fully charged).
The N-channel MOSFET only has 3.3V on the gate, but the P-channel has a 100K resistor between source and gate and a 10K to (switched) ground. This gives 8.73V gate-source voltage with the battery at 9.6V, increasing if the battery voltage is higher.
I had the main power switching device fail on a prototype main X9E board (twice), this could be the reason.
I wonder if this is also related to the X9E of a club member who had a problem with static causing his X9E to power off?

A possible fix would be to reduce the value of the 100K resistor (add another 100K in parallel would be good).

Mike
erskyTx/er9x developer
The difficult we do immediately,
The impossible takes a little longer!

User avatar
jhsa
Posts: 19428
Joined: Tue Dec 27, 2011 5:13 pm
Country: Germany

Re: Taranis X9E, how know which component it is?

Post by jhsa » Mon Feb 22, 2021 12:44 am

MOSFETS don't like to be working very close to their maximum gate voltage. They will eventually get destroyed.
I remember the Ar9x board used AO3401, which has a Gate/Source max voltage of 12V, and I thought it was quite low.. The latest version used the AO3407A (20V). This Transistor is very cheap and it is rated at about 4A. It is my favorite Mosfet for this type of switching.. :) Well, Mosfets are perhaps my favorite component. :mrgreen:
The guys that designed the radio should have paid more attention to their Math lessons :mrgreen:
This is a good reason for me not to trust this radio.
João
My er9x/Ersky9x/eepskye Video Tutorials
https://www.youtube.com/playlist?list=PL5uJhoD7sAKidZmkhMpYpp_qcuIqJXhb9

Donate to Er9x/Ersky9x:
https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=YHX43JR3J7XGW


Post Reply

Return to “Hardware”