Forgot to mention that I've tried reading the serial (again using an arduino as a bridge), but only got some strange characters. Tried multiple baudrates, without any different result. Hope the logic analyzer can help further with this

Thank you all for your answers!

I managed somehow to read some bytes' values using an arduino as a bridge, but I didn't manage to distinguish any pattern in this data. I've made all the digits to display "1" (so this means only the segments are light up) and imported the data into excel, where I expected to see repeating pattern of bytes which value is the same (the value of "1") , but this did not happen.

I guess there is another data going on these pins, as it uses the RX and TX of the main IC. I've even ordered a cheap logic analyzer and I hope...

Hello, I have a device which uses 3 7segment displays (4 digits each) controlled by a single led driver (TM1629A) which is controller by a microcontroller (MS51FB9AE).

I want to capture the communication between the 2 ICs, so I can decode it and read it from PC with USB cable.
The problem is that this task is slightly over my skills and I have no experience is such tasks.

I would be grateful if somebody give a hint how can I read and decode the digital signals or share a source where I can educate myself on this matter.
I have no idea what protocol is...

Thanks for the advice, but don't do it blindly. I am increasing gradually and first checked the CPU so I am sure it is not shorted.

After further investigation today, I noticed that actually when I plug the charger, 20v goes to the 3.3V mosfets' gates.
After checking the gates resistence to main power rail on charger unplugged there was about 10k+ ohms resistence.
Applying 1 volt to the gates and the 3v and 5v controller chip takes about 250mA power.

I dont have another RT6575 to replace and try, but I wonder if the gate pins were shorted to 20V, wouldn't...

Hello!

I am still learning on laptop repairs and I am currently working on the above mentioned device.
Currently the laptop is dead (no power on). The device takes 2-3 mA when 20v are injected onto the charging plug.
Main power rail is present (20v), but no other power rail is present, including the 3v and 5v. I noticed that when no power is connected the 3v and 5v coils have large (normal) resistence to ground, but when I plug the power, both are being shorted to ground.
I wonder is that an expected behavior or there is an outer protection activated.

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