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  • SadSack
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14 Oct 2013 14:03
Replied by SadSack on topic DEVO7E replacement LCD

DEVO7E replacement LCD

Category: Feedback & Questions

Well I only needed to build module for my FG and confident that will be fine. Only thing I would 'like' that i can use Futaba's 12 channel PPM.

Hubsan TX is an accident to be honest, welcome one :-) Wouldn't even have done it if i hadn't broken my LCD i was going to use for RF module. OLED does look right in that space and for Fg module perfect.
I'm going to re used PCB in TX. Got a7105 + amp and have some old low power cypress module that i maybe able to use. And I'll get to use Midelic for RX so winner all round if you ask me.

The code I have no Idea with I just fluke getting oled running its NOT Arduino!! PB written so much that you only needed to join the dot's. PB did start to 8S upgrade longtime ago and TFT with touch screen are only $8/9 each.

Only things out standing or untested:
DFU loader : Now i found opensource one but as above No idea how to change it. Why i say this is because I can flash my devo 7e with no loader using STLink v2 steps >erase>flash @ 0x08000000>then flash again without erasing>@ 0x08003000> and that does work but you have do that every time there's a change to code. Which is fine for me but I never managed to do that using usb/serial ie ST's bootloader but if I download the whole flash. I can use that with usb/serial.
The power down circuit PB has posted that info here but I plan to use momentary switch. No idea how that will effect things.
  • shadow
  • shadow's Avatar
02 Jun 2013 01:04 - 06 Jun 2013 22:38
Help heard a pop in trasmitter was created by shadow

Help heard a pop in trasmitter

Category: General Discussions

Ok i was setting up my new model in my devo 8s on a devo 12 rx.
I had a 3s battery hooked up.

When I heard a pop and the TX was dead unplug the battery and could smell fried circuits. I opened it up but nothing looks burnt :S

What should I check?

Edit:
Ok further disassemble I found this on the back side of the board does anyone know what this is? It looks like maybe a transistor.

update:
Further investigation got the tx to power up without the module. After removing the rf shield Found burnt board.

Update: The part that fried on the main board is a IRLML6401PbF
www.irf.com/product-info/datasheets/data/irlml6401pbf.pdf
hexfet power mosfet
  • PhracturedBlue
  • PhracturedBlue's Avatar
07 May 2013 12:33
Replied by PhracturedBlue on topic Devo 8s Found a resistor BURN

Devo 8s Found a resistor BURN

Category: Feedback & Questions

Actually mine is a 6.8Ohm as well. I just read what was on the silkscreen (10ohm) and assumed they'd followed it.
The power circuit is a bit odd. I have a full diagram of it somewhere. I think there is something wrong with it as I smoked one of the switching transistors doing nothing more than turning the Tx on/off (the cheap switch failed which somehow led to the transistor burnout). It is also possible that the resistor does get really hot due to the Lipos, but hasn't failed. Did you check it with an ohm-meter (with the batteries removed of course)?
the full voltage also goes directly to the CYRF Module which has its own ldo. Rereading your 1st post it isn't clear if you are having a range issue or if the tx is no longer functional. If it is only a range issue, you probably burnt out the cyrf power-amp. The only way to know is to remove the shield and check it.
  • RandMental
  • RandMental's Avatar
07 May 2013 10:59
Replied by RandMental on topic Devo 8s Found a resistor BURN

Devo 8s Found a resistor BURN

Category: Feedback & Questions

Since we are speculating - I don't have mt 8s close so I cannot trace the circuit, but right next to it on the photo in the first post is an UTC78D06L, which is a linear voltage regulator delivering 6.0V at 500mA max. This I believe is the NiMH charger circuit as the rest of the electronics runs on 3.3V.

Based on the value and size my guess is this resistor either drops the voltage from the external charging connector (should be max 12V) and thus splitting the power dissipation (heat) between the resistor and the 78D06L regulator chip;

OR

It drops the voltage from the battery pack (up to 6V when charging) to lower the power dissipation in the 3.3V LDO. That could explain the RF power drop since it burned, as it would probably now have a higher value.
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