Macintosh Portable M5126 - Battery problem - Good night :0)

[Scouter3D]

Hi,
my name is Tom and this is my first post in this forum. I run a small online homecomputermuseum site and i repair a lot of vintage computers.

Now, i am in the process of fixing a non working Macintosh Portable M5126 for a friend

After recapping and fixing 3 broken traces / Vias the mac greets me with a chime and boots a systemdisk from the diskdrive.

BUT: then i get the "no reserve battery power - good night" message imediatly after the system is bootet.

BTW: the battery is a new replacement one and gets charged from the mac and meassures around 6V, but the mac battery menuitem shows battery level at 0%
the small battery compartment switch is working and both buttons (reset and inerrupt) are working.

Without the powersupply the mac does not startup at all / or only 1 second...

Yes, it is possible that there are more bad VIAs

It would be great if someone could give me a hint where to search, or what to meassure (i can use my oscilloscope) ... to narrow down the search-area :0)

Cheers and many thanks in advance, TOM:0)
PS: Sorry for spelling mistakes, as my native tounge is german (i am from austria)

PSPS: is there a correct schematic for the M5126 somewhere?

 

[Scouter3D]

Hi,

i just started meassuring around with the osci and i found that +5V is not +5V but 6.something with a lot of ripple... :0(

Cheers, TOM:0)

 

[Scouter3D]

I have watched all the videos from @techknight regarding mac portables, => very informative and a great help!!!!! Thanks!

In one video he removes a few of the smd chips and finds cap-rot beneath...

I thought the area looked fine, but decided to remove the resistor-array => and found at least one VIA completely gone...

Next step: patch it up and remove the other smd chips in the area...

Cheers, TOM:0)

 

[Scouter3D]

I have removed two more smd chips and found no more corroded traces... :0)

Find a picture attached for future reference of the traces under the chips... so you can check for continuity without removing the chips...

Red: Topside, Blue: Bottomside

Cheers, TOM:0)

 

[NullCipher1337]

Hi Scouter, did this fix the issue? I have no idea what this is until now, it's very cool though from the Wikipedia picture! How long does it last on battery?

 

[Scouter3D]

Hi, i am currently working on it... i will keep you updated if this fixes the problem...
Cheers, TOM:0)

 

[Scouter3D]

Hi and Eureka!

after soldering everything back and patching up the bad VIA the Portable has the correct voltages, recognizes the battery and its charging-level, boots from Floppydisk even without an external PSU attached... NICE :0)

Sadly, it will not boot from the BlueSCSI but that may be fried from the overvoltage? I guess the owner will try it with another one...

That´s it for today!

Cheers, TOM:0)