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Thread: Toshiba T1200XE - capacitor problem maybe?

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  1. #1

    Default Toshiba T1200XE - capacitor problem maybe?

    Bought Toshiba T1200XE laptop a while ago. Today I finally got charger for it and tried powering it on. At first attempt it booted fine to DOS. I powered it down and then tried to take video about the whole process but this time it did not boot but instead shut down and haven't powered on since.

    Here is the video:
    https://youtu.be/fMU3-zS88fw

    The DC-IN led blinks so there is most likely something wrong with the power board, the led blinks even in the video. There is strange smell coming from where the power board is located so I expect that capacitors leaked now, it doesn't smell like something has burned, the smell is just, weird... I did open the machine slightly before I even got the charger and caps looked fine (I took picture then which is attached), haven't opened it now but I will later.

    Other than caps, what else could be broken from the power board, in most cases with this machine? What is the purpose of Reset button on the back?


    EDIT: OK, I disassembled the machine and indeed there are atleast two capacitors which have leaked, one is near where the "sub battery" connects (picture attached). I also noticed that when I connect charger the led blinks but quite randomly. If I waited some time it would stop blinking and then I could try powering the machine on, it would fail and then the led would blink in constant "rhythm". After disconnecting the charger and waiting some time this process could be repeated.

    I have now removed those two capacitors and ordered replacements.

    EDIT2: By the way, is the sub battery necessary for powering the machine on?
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    Last edited by fin-william; August 27th, 2018 at 10:14 AM.

  2. #2
    Join Date
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    I have a Toshiba T1000LE with similar problems. Did you have any progress with the caps replacement? Have you figured out the sub battery? I can't seem find the function or necessity of it?

  3. #3

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    I have only replaced some of the caps so I have been unable to test yet, but I will post an update when I can.

  4. #4

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    I seem to have problem with this. I replaced most (not all) capacitors, ones which I saw were leaking. After doing this same symptoms were present, no change.

    After that I removed both 470uf 25v capacitors and under one of them I saw leakage again. I tested both with the capacitor tester I bought from eBay, cheap one yes. Both of them check OK.

    I installed them back and now there is something wrong, my chargers led flickers rapidly when I connect it to the power board, I guess there is short somewhere? I have tried to see if I soldered something wrong but cannot find anything which looks like that.

    This happened after I removed and reinstalled those to caps so could they cause this sort of behavior? They failed totally after being removed?

  5. #5

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    Update:

    I did some random reflowing of several components, just heated their legs to melt solder. I did removed and reinstalled those 470uf 25V caps again as well and now it's back to the same state as it was before:

    After the charger is connected, the red led starts to blink in random pattern but will then glow without flickering. When this happens, I can try powering on the machine but obviously it fails and then the led blinks with clear pattern.

    Here is a video:

    https://www.youtube.com/watch?v=1Poqg9UZXtQ

    It is worth noting that I haven't replaced all capacitors, maybe I should before trying to even test... those two 470uf 25V will need to be replaced because atleast one of them was leaking.

    EDIT: CMOS battery is dead as is the resume battety of whatever it is called.
    Attached Images Attached Images
    Last edited by fin-william; October 6th, 2018 at 12:47 AM. Reason: Added some pictures which I took

  6. #6

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    Hi,

    I was just looking at the photos you posted. Often when the electros are at the end of their life and dry up, they internally gas and the pressure makes them go domed topped. But the ones there look ok in that respect. It is worthwhile testing them, before replacement, in circuit, with an ESR meter. It might possibly not be the capacitors at all.

    However, there is clearly a problem with one of the Mosfets there (see attached modified photo). It has significantly overheated with discoloration of the resin body and the crystallization of the solder connection to the drain connection (central pin). I assume it is a mosfet due to one pin clearly being labelled "G".

    I would remove this mosfet for testing and put it in a test circuit. It will either be a P or an N channel type, most likely N. It might have a readable type number on it, or be the same as the one that looks ok nearby. I think likely it needs to be replaced.

    Hugo.
    Attached Images Attached Images

  7. #7

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    Also, I am seeing something else.

    If the original battery was the yellow Toshiba one with the red and black wires and those wires were connected to the plug & connector PJ2 in the area where the corrosion is ? ....if that is the case, then I think what you are seeing is not leaked electrolyte from an electrolytic capacitor.

    It looks to me as though the corrosive liquid had emanated from the connector plug that plugged into socket PJ2. This can happen with leakage at the battery and the battery electrolyte travels down the wires around the strands, but inside the PVC sheath. Notice how the gelatinous and corrosive material is concentrated in and on the plug. So the wire can act as a conduit for the delivery of the battery electrolyte. You could confirm this by stripping back the red & black PVC off the wires and looking at the strands and wire contents for evidence liquid & corrosion.

    Also, in your photo on the original post, I'm not sure if the electrolytic capacitors are the originals, or if this is a photo of after they were replaced ? If they are the originals, it is unlikely they leaked, those types, while prone to drying out with age, seldom leak (they can in some cases) but its a lot less common than leaking surface mount electrolytic types.

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