Member Avatar for mjamike

Hello,
A customer of mine dropped off a Dell Latitude D600 notebook that runs fine using battery power but shuts off when plugged in. Short circuit maybe? The strangest part (to me) is that the battery charges when the laptop is off and plugged in. If you try to power on the laptop with it plugged in, it briefly lights up the numlock, scroll lock and caps lock LED's then shuts off. If you then unplug and power on using battery it works fine... until you plug in again which causes it to shut off immediately.

Is there some sort of electrical path that only the AC power travels on that is shorting the machine out? I am not educated enough to know how to test individual parts of the motherboard for shorts. So far all I have done is try another AC Adapter which had the sam issue. I have stripped the machine down and have physically inspected the motherboard and haven't seen anything that stands out. I can post some high resolution images if that helps.

Any help would be greatly appreciated. I hope I can help others here in the future!

- Mike

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Dani AI

Generated

This symptom (works on battery but dies as soon as AC is applied) usually points to the AC/DC input / charging path on the mainboard rather than the battery or OS. Thanks to for confirming a motherboard swap fixed the unit and to for flagging the charger-board possibility — those outcomes are useful clues when choosing whether to repair or replace.

Quick, safe checks to narrow the fault:

  1. Verify the adapter output with a meter (voltage and polarity) and try a known-good adapter.
  2. Remove the battery and power the machine from AC only. If it still shuts down, the DC-in / regulator path or a shorted rail is the likely culprit. If it stays on, the fault is probably in the charger/or-ing hardware.
  3. With the battery removed and AC connected, monitor main rails (+3.3V, +5V, CPU core rail) — do any collapse immediately when AC is applied?
  4. Check DC jack and nearby SMD fuses for opens/shorts and visible damage (burn, bulging caps, blown TVS diodes). Use the multimeter diode/check mode on MOSFETs and diodes.
  5. If a short is suspected, use a current-limited bench supply or a series lamp to avoid further damage while tracing the short.

Common board-level causes: failed charge-controller MOSFETs or diodes, shorted or leaky electrolytic/ceramic capacitors, blown SMD polyfuses, or a damaged DC-in jack/board. On machines with a removable DC-in/charger daughterboard the repair is inexpensive; on integrated designs replacing/reworking SMD power parts or the entire mainboard may be required (as discovered).

Safety and next steps: use ESD precautions, never probe live boards carelessly, and consult the service manual or schematic if available before component-level work. For Toshiba owners like and the same isolation/tests apply — if the DC jack is a separate module, try swapping it first; otherwise consider a board-level technician if comfortable soldering SMT parts is not an option.

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Member Avatar for techno t

Could well be due to a fault on the charging circuit. Tell me, does it come with a seperate Charger Board? These are notorious for causing charging and power faults.

If it does have a charger board try swapping it with a good known spare (ebay is your friend for that)

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Member Avatar for mjamike

Techno T,
Thanks for the reply. Unfortunately the charger board is not separate from the motherboard. I swapped the entire motherboard and it works fine now... but I would have loved to have fixed the original one :(

Thanks for the help... now I will check for separate charger boards on future repairs!

- Mike

Member Avatar for techno t

what a pain, sounds like the charging/power circuit is faulty with would mean changing the power reqs and other SMT parts (a pain to find and match up)

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Member Avatar for KELVINZ

Wow i have a toshiba laptop and no so long ago my computer when plugged in shuts down so i have to shut it down in order to charrge it do you knoow what could be the issue please help?

Member Avatar for truda

i have the exact same issue as kelvinz!! My laptop is also a Toshiba.. please help, i dont know what to do

Member Avatar for jingda

Hi truda, you can start first by creating a new thread instead of adding one. And if you do that, we also need more information about your laptop and problem. Thanks.

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