Macintosh Portable Troubleshooting

[Stephen_Usher]

Q16 does control the +5V line, as can be seen in the circuit schematic that techknight posted above. Looks like at some point there might have been a short circuit on the machine and it overheated the component. The IR9230 components are cheap and relatively easy to remove with a hot air reworking station so if you can I would change it.

 

[techknight]

It still looks like you are using original caps!!

 

[Mastergeko4]

It still looks like you are using original caps!!

Oh no. That’s an old picture before I did the recap. I already replaced all the caps on the board. 

 

[BlaBla1985]

on my logicboard, 2 traces on the right end of the hybrid were heavily corroded and made an almost short on 2 pins. There is only a Cap on the other end of those (C18 on the logicboard i believe) and it should be high resistense. it also booted sometimes from disk but it mostly failed halfway.

i ended up cutting the 2 traces completly and bodging them with some wire. it's been working fairly good ever since.



the 1 meg ohm resistor is no longer there btw

 

[techknight]

That's what happens to them, and the screenprint laser-etched resistors go open, traces go open, etc... Yours has a couple traces going to those resistors that are starting to get bad. 

the 1Meg ohm is a solution on some circumstances where the resistance goes open. 

My goal was to reverse engineer it back into a schematic and recreate the Hybrid, but just never got around to it. I have a Hybrid IC that was broken into 2 peices which would make a good candidate for this process. 

 

[BlaBla1985]

i guess the hardest thing in reverse enginering it are those resistor values. i tried to probe around on the hybrid during my troubleshooting, but that really didn't help much without any knowlegde of the actual components. it was more of an accident that i found that short while looking at the chips datasheet to see what it does.

 

[Mastergeko4]

on my logicboard, 2 traces on the right end of the hybrid were heavily corroded and made an almost short on 2 pins. There is only a Cap on the other end of those (C18 on the logicboard i believe) and it should be high resistense. it also booted sometimes from disk but it mostly failed halfway.

i ended up cutting the 2 traces completly and bodging them with some wire. it's been working fairly good ever since.

View attachment 34127

the 1 meg ohm resistor is no longer there btw

That seems like it could work. I also want to see if fixing that Q16 component fixes anything. Does the Hybrid Board have any traces on the underside? 

 

[Mastergeko4]

Q16 does control the +5V line, as can be seen in the circuit schematic that techknight posted above. Looks like at some point there might have been a short circuit on the machine and it overheated the component. The IR9230 components are cheap and relatively easy to remove with a hot air reworking station so if you can I would change it.

I might look into replacing that thing. That could be the cause of the issue. Where can I buy one?

 

[Stephen_Usher]

I might look into replacing that thing. That could be the cause of the issue. Where can I buy one?

I'm guessing that you are in the USA, in which case Mouser should have them.

 

[Mastergeko4]

I'm guessing that you are in the USA, in which case Mouser should have them.

Alright, I’ll check them out. What is the component called? 

 

[Stephen_Usher]

This should do according to the schematic
 
Mouser No: 844-IRF9Z30PBF
Mfr. No: IRF9Z30PBF
Mfr.: Vishay Semiconductors
 
You can see the designation on Q14 and Q15 in the picture posted above.

 

[Mastergeko4]

This should do according to the schematic
 
Mouser No: 844-IRF9Z30PBF
Mfr. No: IRF9Z30PBF
Mfr.: Vishay Semiconductors
 
You can see the designation on Q14 and Q15 in the picture posted above.

Ah, perfect! Thanks! I'll update everyone when the parts have arrived and have been installed. I'll be replacing both of them just in case the other went bad too. 

 

[Mastergeko4]

This should do according to the schematic
 
Mouser No: 844-IRF9Z30PBF
Mfr. No: IRF9Z30PBF
Mfr.: Vishay Semiconductors
 
You can see the designation on Q14 and Q15 in the picture posted above.

Perfect, thanks! I’ll be replacing both of them just in case. They should be coming soon. 

 

[Mastergeko4]

Alright, I’ve just finished replacing the 2 components on the board. The charred one, and the other identical one just in case it was dead too. 
Unfortunately, it still seems to sad Mac a bit but not as often and it still won’t run off the battery. It also still won’t run off the hard drive either. 
I’ve taken a picture of a few of the sad Macs it gives me to see if we can pinpoint the issue. There may be more but these are the ones I see every so often. I have reasons to believe that @techknight was correct about the Hybrid Board being the fault although I can’t see any visibly broken traces. Could there be traces on the other side? 
Let me know what you guys think!