Fried transistor in PB G4, is there hope?

[hayesk]

I dug out my old PowerBook G4 - Aluminum (FW800) and tried to revive it. The drive was dead, so I purchased an IDE->SSD adapter. As soon as I connected it and turned it on, I smelled smoke. After lifting the keyboard I saw this poor little component glowing red and emitting smoke. I don't know if the adapter drew too much power or if it was defective, but now my poor PB is dead. (see attached photo with bulbous component) The PB was working before because I could boot it off of an external FW drive.

I guess my question is is there any hope to source that component (labeled Q26 on the board) or would I be better off trying to find an entire motherboard. I wasn't able to find out what component it was so I don't know if a replacement exists. If anyone has suggestions, I'd appreciate it. Thanks, everyone!

 

[phunguss]

Is this the 15" A1046 (Powerbook5,2), A1095 (PowerBook5,4), or A1138 (Powerbook5,8 DLSD)?

 

[Knife Cult]

Most 2.5" IDE drives are powered by 5v. Most of the mSata type SSDs use 3.3v, so those adapters are supposed to have a regulator on them to reduce the voltage. Some of them do not. So it could be that the adapter fed 5v to a 3.3v device. In this case the drive is also probably damaged. Or, the adapter could be defective and has a short. In either case, you could remove the drive and check that dead FET with a multi-meter. If it failed open you can try to boot the computer on a an external (or DVD) drive. If the computer is alive, then you could probably replace that dead FET. Another option would be to connect the SSD to the 3.3v source in the PowerBook. This would have the advantage of not wasting power (and generating heat) with the regulator on the adapter.

 

[hayesk]

Is this the 15" A1046 (Powerbook5,2), A1095 (PowerBook5,4), or A1138 (Powerbook5,8 DLSD)?

It is the A1046.

Most 2.5" IDE drives are powered by 5v. Most of the mSata type SSDs use 3.3v, so those adapters are supposed to have a regulator on them to reduce the voltage. Some of them do not. So it could be that the adapter fed 5v to a 3.3v device. In this case the drive is also probably damaged. Or, the adapter could be defective and has a short. In either case, you could remove the drive and check that dead FET with a multi-meter. If it failed open you can try to boot the computer on a an external (or DVD) drive. If the computer is alive, then you could probably replace that dead FET. Another option would be to connect the SSD to the 3.3v source in the PowerBook. This would have the advantage of not wasting power (and generating heat) with the regulator on the adapter.

Interesting. The FET is likely dead, as I watched it glow red and smoke came out of it. I'll try to boot it from an external drive when I get back to it, and report back here. Thanks.

 

[Knife Cult]

The FET is likely dead, as I watched it glow red and smoke came out of it.

I'm sure it is. Power components can "fail open" like a fuse, or can also fail closed. The fact that it was glowing means it was still conducting and may have shorted pins inside. Before applying power to it again, I would suggest removing the dead component or checking it with a multi-meter to see if it is shorted inside. It may be a component known as a "high side switch" which is slightly more complicated than a plain transistor. If shorted, it may be connecting different power sources together, along with the control signal. Some of the PowerBook schematics are available.

 

[hayesk]

I'm sure it is. Power components can "fail open" like a fuse, or can also fail closed. The fact that it was glowing means it was still conducting and may have shorted pins inside. Before applying power to it again, I would suggest removing the dead component or checking it with a multi-meter to see if it is shorted inside. It may be a component known as a "high side switch" which is slightly more complicated than a plain transistor. If shorted, it may be connecting different power sources together, along with the control signal. Some of the PowerBook schematics are available.

I think it failed open, but I haven't removed it yet. The good news is I was able to boot from an external FireWire drive, the machine is not a total loss.

I think the next task is to remove it from the logic board, and find out what component it actually is(was) so I can replace it, if possible. This would be the smallest component I've ever attempted to solder, and the markings on top have burned off, so this may be a tough job to find one, let alone solder it on the board.

 

[phunguss]

I think the next task is to remove it from the logic board, and find out what component it actually is(was) so I can replace it, if possible. This would be the smallest component I've ever attempted to solder, and the markings on top have burned off, so this may be a tough job to find one, let alone solder it on the board.

I will pull the top off my A1046 tonight and try to get a photo of the label on top of the component for you.

 

[phunguss]

It looks like component Q26 is marked as 433B4. Someone will have to identify or decode that marking. I hope that helps you.

I have an mSATA to IDE mini adapter inside a 3D printed tray mounted in my PowerBook G4.

 

[phunguss]

Google AI says this:

Single vs. Dual MOSFET Exception. Occasionally, a 6-pin package houses a single high-current MOSFET where four pins are tied together on the PCB to act as the Drain, one pin is the Source, and one pin is the Gate.

 

[joevt]

Powerbook5,2 is code name Q16.
Is there a motherboard part number that looks like one of these?

APPLE Q16 LIBBA EVT PB15" 401243 051-6680 051-6338 051-6888 A1106
    APPLE Q16 MLB PB15 051-6338 REV C.pdf
    APPLE Q16 MLB PB15 051-6680 REV A.pdf
    APPLE Q16 MLB PB15 051-6680 REV B.pdf
    APPLE Q16 MLB PB15 051-6680 REV E.pdf

APPLE Q16A 051-6809 051-6570 051-6653
    APPLE Q16A ENZO RAMP BATTERY 051-6573.pdf
    APPLE Q16A MINI RAMP USB 051-6571 R01.pdf
    APPLE Q16A TT RAMP SOUND 051-6572 R01.pdf

APPLE Q16C 051-6929
    APPLE Q16C FLASH LEFT SENSOR 051-6849 R01.pdf
    APPLE Q16C SHOCK USB 051-6848.pdf
    APPLE Q16C SPRINT BACKUP BATTERY 051-6846.pdf
    APPLE Q16C TATIC AUDIO IO 051-6847.pdf

 

[joevt]

Q26 is probably this TRA_SI3443DV found on sheet 34 in the schematics.

 

[hayesk]

Wow, this is great information! Now I can order a replacement. Thank you so much for your help!

 

[joevt]

Wow, this is great information! Now I can order a replacement. Thank you so much for your help!

What's your motherboard part number? Just curious if it matches one of the posted documents.