(tr)uSDX Forum

I was measuring with an ammeter the absorption in rx mode, about 80 mA, and after a few interruptions of contacts, I kept the test leads between the battery and the power cable, the display turned off. The radio turns on but the display remains off. What could have happened, it is not possible that the display broke!

Luca66 wrote: ↑12 Aug 2022, 14:29 I was measuring with an ammeter the absorption of the radio in reception, about 80 mA, and after a few interruptions of contacts, I kept the test leads between the battery and the power cable, the display turned off. The radio turns on but the display remains off. What could have happened, it is not possible that the display broke!

Is the radio in the case?

Yes, the radio is in the case. The polarities were not reversed, I just tried to measure the current draw and I repeatedly connected and disconnected the battery. The ammeter was in series on the positive line. I tried the reset but it didn't work. I don't even want to think that it is possible to damage the radio by repeatedly connecting and disconnecting the battery. Now I will try to reinstall everything, bootloader and firmware. Do you have any guess or idea?

I think you are on the right track, firmware or bootloader corruption.

AC9YY wrote: ↑12 Aug 2022, 19:35 I think you are on the right track, firmware or bootloader corruption.

Failed attempt. I reloaded the bootloader and firmware, but the display does not turn on. The radio turns on. Unfortunately I think the display broke, for a reason that I struggle to understand.

I have already ordered the replacement of the oled, but I ask if other components should also be investigated. Thanks for any suggestions.

Before disassembling the oled, I would like to check the voltages at the GND, VCC, SCL, SDA ends. Do you know the voltage values ​​that must be found on those points? Also I thought the oled modification jumper may have disconnected.

I measured the voltage at the ends of the OLED contacts, feeding with 12 V. GND- VCC = 4.92 V (CONSTANTS), GND-SCL = FROM 2.8 TO 3.24V (CYCLIC), GND-SDA = FROM 3 A 3.24 V (CYCLIC). Are these voltages correct? How can I tell if the OLED is really broken? I enclose the photos of the pcb, I do not seem to notice signs of burnt components.

Where does the 12V (white wire) go ?
That´s not how it´s supposed to be.....

If you did the 8V Mod, or even applied 12V to the OLED, that´s most likely the reason why it died.

And yes, they can die ! P.S: good luck with unsoldering the OLED ! That´s not very easy without hot air soldering.

73 Manuel; DL2MAN

Rose metal could help. Apply it in abundance to all four pins then heat them all it once. Should go out easily.
Don't forget to clean remains thoroughly with soldering wick before soldering it back.

DL2MAN wrote: ↑14 Aug 2022, 23:04 Where does the 12V (white wire) go ?
That´s not how it´s supposed to be.....

If you did the 8V Mod, or even applied 12V to the OLED, that´s most likely the reason why it died.

And yes, they can die ! P.S: good luck with unsoldering the OLED ! That´s not very easy without hot air soldering.



73 Manuel; DL2MAN

Hi Manuel, thanks for the reply. The white wire connects the capacitor C6 to 12V. I got the 12 V from the terminal of the 14 pin strip. Did I misinterpret the mod? What tension did I have to apply?What do you tell me about the voltage values ​​that I have detected?
Thank you.

LILO wrote: ↑15 Aug 2022, 00:10 Rose metal could help. Apply it in abundance to all four pins then heat them all it once. Should go out easily.
Don't forget to clean remains thoroughly with soldering wick before soldering it back.

Thanks for the reply,
What is rose metal?

bismuth + lead + tin

https://en.wikipedia.org/wiki/Rose%27s_metal

Avoid mixing bismuth and lead in your electronic soldering. The lead and bismuth make a very low melting point combination that is I think brittle. Bismuth alloy makes a good low temp solder but you have to avoid letting it mix with lead. I think chip quick uses indium.

It's not for soldering. It's for easy desoldering of stubborn components only. With 95C melting point it greatly helps to not to overheat the board or damage something.
After that clean your soldering iron tip, tin pads/pins with regular 60/40 solder and clean with wick. Repeat 2-3 times. That's all.
Board is ready for soldering. No problems guaranteed.

Regards,
Andrey

Start around 9:20 in this video. https://dl2man.de/2-trusdx-assembly/

AC9YY wrote: ↑15 Aug 2022, 15:15 Start around 9:20 in this video. https://dl2man.de/2-trusdx-assembly/

Ok, now, I understand the problem!
I powered the oled with 12 V instead of 5 V. I tested its duration for about 4 months. Now I will replace the oled and feed it as described in the video. Thanks for the help and advice.

Replacement done, working OLED! I want to share my experience with you, to avoid the mistakes I made for others. Important: buy only OLEDs without the soldered pin strips. The method I followed had only one main goal, to avoid unsoldering the pin strip on the main board. The tools needed are, pliers, tin pump, copper braid, solder paste and soldering iron, antistatic gloves and cutter.
1. Proceed to unsolder the broken display from its pin strips.
2. In my case I had to unsolder the pin strips from the new display. Cut the black plastic segments with the cutter. Then proceed to unsolder the four pins. In my case, doing this I ruined the leads of the pcb. I therefore had to redo the connections of GND and VCL destroyed in removing the pins
3. Modify the new display according to the indications of the forum.
4. Re-solder the new display on the pin strips already present on the main board.
Work time about 2 hours.
I hope it was useful.