Ok good start. I would check the resistance to ground on the 1.8v rail before powering it on (with and without emmc connected)
1.5 both connected and disconnected
1.5 ohms on the 1.8v rail? hrmm, what about your other rails?
Can you point out what lines and what test points i should use to test?
Not sure if I am doing it right hahaha.
1 Like
Thanks, I will update you this afternoon.
I’m back now, replaced BQ and still got no shorts.
These are the values I got from those rails:
(con = emmc connected, dis = disconnected)
Thanks a lot for the help.
Are those diode mode readings? What do you get in resistance mode?
My bad, those readings are completely wrong. Don’t even know what mode I was using lol.
Here are the good ones, same values both disconnected and connected emmc:
Readings are in kohms.
They all look a little low, but the top two particularly so. I would avoid powering it up until we can work out why. I would usually expect the top left to be in the 100k or meg ohms area, and top right to be 5k or 10k.
Does having rcm mean that the CPU is not shorted?
I would concider it a good sign. We need to work out what is pulling those two rails down. Measuing at different locations on the same rail can help narrow it down, but i dont know those locations. There is probably pictures in other threads that can help.
I would be tempted to remove the M92 though, as it is fairly easy to do so, is on tje 1.8v rail and attached to the BQ which we know was bad.
Just found this which may or may not be useful for seeing which of the yellow ones has lowest resistance to ground.
Replaced M92, going to test those points now
Another thing I noticed:
The fuse above the USB port is bridged. No idea if the previous owner did it just for the sake of it or because it was tripped.
Ah, well presumably it blew at some point, and if the root issue wasn’t fixed that may have caused something else to blow. I am a little confused by your readings though I probably need to see what I get on mine in a bit. Maybe @Severence has some better ideas? I would be suspicious of the M92 given that the fuse is bridged.
These results were taken after the M92 replacement,using a multimeter in resistor mode set to the 2M ohm setting.
Ah, you have changed the M92 now? What are the measurements on the coils now then, have they changed?