Jump to content

Portable - two steps forward one back

Recommended Posts

58 minutes ago, at0z said:

So P37 always showing 2.75v, when power first connected, during PMGR restart buttons held and after reset.


Trying a buzz out is interesting - the schematics for Q10,11,13 appear to show all three legs connected but on my board the middle leg is clipped in each case. No buzz on any pins. I did get a buzz on J21. So not sure if the schematic is "wrong" or I need more coffee...or both. But if I'm getting voltage on that pin, does that mean it doesn't matter ?

FYI, on those transistors, the drain connected to the board is on the 'top' side, opposite the pins.

Link to post
Share on other sites

I knew I should have added the disclaimer "this was a before shot for example use only".


But I did screw up my pin numbering on the PMGR chip so the ACTUAL reading on pin 37 is a more healthy (?) 5.17v and from there to the major players (GLUs and VIDEO and edge connectors and Q10/11/12) we do ring out. So at least it appears the roads are open.


Now I don't know if it was a trick of the light, but I thought I saw out the corner of my eye a flicker on the power draw from the lab supply at random, sometimes I think up to 400mA. Of course if I stare at it, it doesn't happen. I'll do some exploring of the board with my fingers, maybe something is a dry joint...

Link to post
Share on other sites
9 minutes ago, desertrout said:

Good lord, I wonder if we should be running these machines at all....

Thanks techknight for the second opinions on the PMGR. I have a dream there is an Indiana Jones warehouse with dusty crates crammed with excess Apple components inventory from when the Portable production line was shut down. And then I woke up screaming. 

Apart from obvious voltage abuse, do they just have self destructive tendencies?

Link to post
Share on other sites
32 minutes ago, techknight said:

SYS_PWR has to be pulled to 0v for the system to come up. This is the responsibility of the PMGR. 


Chances are, the PMGR is bad. ive used up all my spare PMGRs on parts boards, thats how often they go bad. 

Does something external to the PMGR initiate that drop ? I guess we need an Evil Genius to reverse engineer that custom chip...

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...