820-01823 no power

Kyle93

Active member
This arrived with no power. No obvious damage on the board.

While measuring rails, they are all present up to PP3V3_S5

Diode mode on PP3V3_S5 is 0.008. Only 9.6 ohms.

While injecting voltage only U1200 gets warm.

On a side note PP1V05_S5 voltage is fluctuating


Can this chipset can be purchased anywhere else besides Aliexpress? It is a SRH13
 

Kyle93

Active member
Before measuring rails a DFU revive was also performed and completed successfully even though nothing ever appeared on the screen.

Should something else be checked?
 

Kyle93

Active member
PCH replaced successfully. Board turns on chimes and boots now however no image or backlight on the screen. The first three lights come on but light 4 and 5 remain off.

Do you need to perform a DFU revive after PCH replacement??
 

Kyle93

Active member
No external video with and without internal lcd connected. Caps lock light comes on

No change after DFU revive
 
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Kyle93

Active member
When testing external I plug in through usb-c port and turn the imac on. Do any special keys need to be pressed on the keyboard during testing?
 

2informaticos

Administrator
Staff member
New PCH requires clean ME region.
Actually BIOS is hold by T2, so you need to pass through DFU.
Maybe solve the video problem too.
 

Kyle93

Active member
Once I am in DFU whats the next step? I have never cleaned ME regions manually before, only used the Medusa programmer to do it.

Does a dfu restore need to be performed to clean the ME region?
 
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