Dell EC chip warm/hot before power-on - normal?

[survivalbloke]

This is a shot in the dark, and if you need more info, I'll give it all to you. I've already asked for the schematics and boardview.

This board won't power up. Has 3.3v on BIOS chip pin 8, 3.3v on power button, confirmed voltage to 0v when pressed power button. The EC chip is quite warm just with the power adapter connected and nothing else. Board is out of the machine and everything disconnected. I'm guess that's abnormal and probably the reason for not powering up. I'm still learning and have been fault tracing with my level of knowledge.

Just wondering if the EC chip being warm/hot is irregular. If so, I'll stop here.

Board is a Redwood 14296-1 PWB: 7M6GF

[mcplslg123]

Re: Dell EC chip warm/hot before power-on - normal?

EC should'nt be warm in any conditions. You need to check whether EC's VCC pin is shorted or showing low resistance. Whats the resistance on 3V LDO?? What's the consumption on dc supply??

[survivalbloke]

Re: Dell EC chip warm/hot before power-on - normal?

EC should'nt be warm in any conditions. You need to check whether EC's VCC pin is shorted or showing low resistance. Whats the resistance on 3V LDO?? What's the consumption on dc supply??

Thank you. Resistance VCC to gnd is ~25ohms. Consumption is 83ma. I was unable to locate 3V LDO as I don't have a schematic. I do have a boardview which I'm attaching to this post, although oddly, it doesn't match exactly what I'm looking at. It is pretty close though. Just some caps and resistors not in the place they appear in the boardview.

[mcplslg123]

Re: Dell EC chip warm/hot before power-on - normal?

PU4503,pin3 is your 3V LDO. Exact resistance on this pin?? however, your SIO seems to be defective.