Macintosh Portable Power Up Issues - Display Flashes Once

[SteveHere]

Hi All,

I'm trying to repair another Macintosh Portable.  Non backlit version.  I've done the recap, there were a couple of lifted pads that I think I've properly bodged using the Schematic that TechKnight and others have pointed too in previous posts.

Here's a video of what the computer is doing...

https://drive.google.com/file/d/1xHyM52mSeDQvC__K5vl5rsOiGnJZdsC_/view?usp=sharing

To summarize, the first time power is applied (Using a full battery in the case), Press RESET and NMI at the same time, press a key on the keyboard to power on, the screen flashes briefly, and then powers off.  It won't repeat this behavior until all batteries / power adapter are unplugged, reconnected, then this cycle can be repeated.

I've read in other posts about the Hybrid and Power Manager, is that the part of the board I should be concentrating on?

Thanks,

SteveHere

 

[bibilit]

Hybrid probably. 

A lot of issues when this is contaminated or bad

 

[desertrout]

Possibly the hybrid or PMGR IC (they are on opposite sides of the board FYI), could be other causes as well - electrolytic residue, bad traces, other bad / failing IC's like the SWIM... Have you checked the voltages on the 12V and 5V lines?

For a crazy amount of reference: