Lenovo legion 5-15ach6h IT8227E-192 CXA shorted, repaired but no screen / no boot

[pappothar]

hi
i bought a defective legion, tested it had the IT8227E-192 CXA shorted.
I ordered on aliexpress, carefully changed it under microscope, and now when i plug the dc in, keyboard flashes in all colors in loop, on button is white, and nothing more
The battery led is charging, it seems is the only thing that works
Screen is off, nothing, not even the backlight
could it be a non programmed IT8227E ?
Awaiting for your feedback
Thank You
Stefano

[pappothar]

hi
i bought a defective legion, tested it had the IT8227E-192 CXA shorted.
I ordered on aliexpress, carefully changed it under microscope, and now when i plug the dc in, keyboard flashes in all colors in loop, on button is white, and nothing more
The battery led is charging, it seems is the only thing that works
Screen is off, nothing, not even the backlight
could it be a non programmed IT8227E ?
Awaiting for your feedback
Thank You
Stefano

bump

[Davi.p]

if the chip you replaced is programmable, surely it needs reprogramming, but about the soldering job are you expert enough to say it is right? How is the package? Qfn? bye

[reformatt]

Unless your supplier specifically programmed it for the model you are replacing it on, it will be blank. You need to program it with a SVOD or similar via the keyboard connector (or 128 pin ZIF socket prior to installing). Some Lenovo's have a split EC and KB design, and require programming via JTAG connector. Depends on the motherboard, which you didn't specify.

EC failure on these laptops is usually due to a broken DC input jack sending 19V down the ADAPTOR_ID line directly to the EC. So you need to make sure this is ok first, otherwise you destroy your new EC

[DeXXter]

Lenovo legions need a programmed EC, it won't program iself. And prepare yourslef, because that's maybe not the main issue, most probably a technician was checking the laptops and shorted the 20v rail with the id pin. Happened to me with a legion 5 pro, in the end it had a lot of issue, along with a missing clock signal on cpu, had to reball the cpu and not even that fixed this damn laptop.

[pappothar]

if the chip you replaced is programmable, surely it needs reprogramming, but about the soldering job are you expert enough to say it is right? How is the package? Qfn? bye

Hi
This is mine, they said is already programmed. i soldered under microscope and it seems ok to me

[pappothar]

Unless your supplier specifically programmed it for the model you are replacing it on, it will be blank. You need to program it with a SVOD or similar via the keyboard connector (or 128 pin ZIF socket prior to installing). Some Lenovo's have a split EC and KB design, and require programming via JTAG connector. Depends on the motherboard, which you didn't specify.

EC failure on these laptops is usually due to a broken DC input jack sending 19V down the ADAPTOR_ID line directly to the EC. So you need to make sure this is ok first, otherwise you destroy your new EC

I think you can be right, i found previous owner or technician made a short on one of the DC pins (see pic) to somewhere else, probably to ADAPTOR_ID as you said ; i tested the line and it seems ok now, i checked with the thermal camera, no visible hot spots as previously with the IC shorted

[pappothar]

Lenovo legions need a programmed EC, it won't program iself. And prepare yourslef, because that's maybe not the main issue, most probably a technician was checking the laptops and shorted the 20v rail with the id pin. Happened to me with a legion 5 pro, in the end it had a lot of issue, along with a missing clock signal on cpu, had to reball the cpu and not even that fixed this damn laptop.

Same as above, i think this world is full of "technicians", doing their job badly and reporting failures to customers they made...
"and ot even that fixed this damn laptop" Im an electronic engineer and as you i do not accept a non working hardware as an answer

[pappothar]

Lets' say that now this is the situation

1 - found EC shorted, changed with one bought on aliexpress i paid for programmed, no more short, now the keyboard is on (i can set the KB led color and the power button is white, fans spins)
2 - checked every voltage present on the board, all is present and in expected values ; CPU and GPU warms up
3 - No signal on LCD, not even backlight works, i tested all the pins with multimeter in order to find stange impedances, but found none
4 - i also bought a new bios chip and chenged it but issue remains
5 - i checked also the startup voltages based on the timing (see picture) and nothing wrong to me
6 - The only strange thing is that the display has the +led_vdd and its 20V as expected, but +lcd_vdd is impulsive (see oscillograms)-> i followed up to the CPU_ENVDD from the CPU and that is pulsed too; even the logo on the cover is off