Broken motherboard transistor/resistor

Discussion in 'PowerPC Macs' started by mooesmoo, Oct 28, 2010.

  1. macrumors newbie

    Joined:
    Oct 26, 2010
    #1
    Hi everyone.

    Ive found that one of my powerbooks (g4 1.67ghz model) has this little thing broken. I wanted to know if someone could identify this because i dont know if its a capacitor, transistor or resistor. Only thing i can read on the component is something like "LF T 5A".

    http://img269.imageshack.us/img269/5371/37773497.jpg

    When i checked a correct one with a multimeter i got continuity.

    Thanks and regards.
     
  2. macrumors 6502a

    bizzle

    Joined:
    Jun 29, 2008
    #2
    It's a fuse. Did your Powerbook stop charging? Mine (high res LCD, last revision) stopped charging and the fuse was the issue. I replaced it with one from another older PowerBook G4 board I had and it still powered up with a charged battery (charged from a different computer) but once I plugged it in, ZAP and smoke. Needless to say, it killed the board. I did some research before I pulled it from another board and I could not find any source for these online.
     
  3. thread starter macrumors newbie

    Joined:
    Oct 26, 2010
    #3
    I got the exact same problem. I changed the fuse and again it got a zap. I ordered another ac cable. When you had that problem did you try another charger cable?.

    Do you have any other fuse left?

    Regards

    PS: found the fuse here http://es.farnell.com/jsp/search/productdetail.jsp?sku=1651771 thanks a lot for pointing me that this component was a fuse. Now i just need to know if you tried another charger.
     
  4. macrumors 6502a

    bizzle

    Joined:
    Jun 29, 2008
    #4
    When it fried after I replaced the fuse it fried the power adapter too. I would be very careful. There is something else on the board causing it to happen. I tried multiple adapters before I attempted to repair it. I just called Applecare and complained that it kept doing this (and it's very common, you can read all about it) and they repaired the machine and replaced my power adapter for free.
     
  5. thread starter macrumors newbie

    Joined:
    Oct 26, 2010
    #5
    So did they changed something more on your motherboard? or just the charger? or did they tell you what was wrong.

    Regards and thanks
     
  6. macrumors 6502a

    bizzle

    Joined:
    Jun 29, 2008
    #6
    They replaced the whole logic board and power adapter. They did not tell me what was wrong with it, they never do.
     
  7. thread starter macrumors newbie

    Joined:
    Oct 26, 2010
    #7
    You say its very common and that you read a lot about it. Can you point me where did you found more people with this error.

    Regards and thanks again for all the info.
     
  8. macrumors 6502a

    bizzle

    Joined:
    Jun 29, 2008
    #8
    I don't have any specific links but if you google something about a powerbook not charging with a good battery, you'll find results. I know I did, many on Apple's discussion forum. There was someone else on this forum who traced it back to a blown fuse, the same you found, and the same I tried to repair, but he did not try to repair it.
     
  9. thread starter macrumors newbie

    Joined:
    Oct 26, 2010
    #9
    Did you had applecare or did you just call them? Didnt they saw you had touched some things. And what exactly did you told them was happening?

    Regards and thanks
     
  10. macrumors 6502a

    bizzle

    Joined:
    Jun 29, 2008
    #10
    It was out of Applecare, it was actually like a month ago. I just told them I plugged it in and it went zap poof. The fact of the matter is, it did the same thing before I attempted to repair it, so the fact that I opened it, repaired it, and the same thing happened is irrelevant, so I did not tell them I opened it. I am a ACMT so I am very familiar with working on these machines, they had no idea it was opened.
     
  11. thread starter macrumors newbie

    Joined:
    Oct 26, 2010
    #11
    No luck then for me, cause i got this laptop from another guy and you can see that someone opened the computer before.

    So the problem is that even if i change the fuse it will brake the charger, thats what happened to you?

    Regards.
     
  12. macrumors 6502a

    bizzle

    Joined:
    Jun 29, 2008
    #12
    Yep. I replaced the fuse, turned it on, it was fine. I plugged in the power adapter to see if it charged and it fried the logic board and the power adapter.
     
  13. thread starter macrumors newbie

    Joined:
    Oct 26, 2010
    #13
    It might be also the coil inductor. ALthought i dont know how to see if its broken cause with the multimeter i see continuity.

    Regards.
     
  14. macrumors newbie

    Joined:
    Nov 16, 2010
    #14
    PB 17 1.67, also blowing power supplies.

    Hi, I'm pretty keen to know how you (or anyone) got on with this, as I have a 17" with a similar illness.

    The first symptom was a very dark screen. It seemed to be off, but light shone from behind, through the Apple logo, revealed an image. Reset the PRAM and the PMU, no change. Video out was fine, and it booted to desktop. Odd behaviour from the keyboard backlight: it came on in the light, and went off if the right sensor was covered.

    Then, after a couple of tries, it blew the power supply (65w Apple).

    Fitted a known good display and used another 65w Apple power supply. Display illuminated at the grey screen, but went dark before it got to the desktop. It reached the desktop, and the power supply mains fuse blew.

    The original display was dark on a good machine, but the replacement seems to have survived intact.

    Any ideas? :)

    (Maybe I should start another thread with this, too)
     

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