Member Avatar for The STIG

My Vaio laptop (model VGN-FS742/W) will not power up and does not show that the battery is charging.

I was using it and the battery was getting low (but not too low that it was going to shut down). I pluged in the AC power cable and the laptop just went dark. I thought maybe the battery was lower then I thought. But it would not come back up. Nothing I have done has got even a hint of power of any kind.

I confirmed that the AC power adaptor is working and making the voltage it should be with a multimeter. I also used that AC power adp. to power up a diffrent Vaio and it worked fine.

This machine is like my right hand so any help on this would be great.

Thanks

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  • Latest Post Latest Post by k kiss

Dani AI

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Given the troubleshooting already noted by , and others (adapter verified, battery swapped, minimal‑configuration checks suggested by ), the failure most likely lies in the DC‑in path or the board’s power circuitry rather than the external parts. The next steps are targeted, measurable checks and a focused visual inspection so the problem can be isolated without needless parts purchases.

  • Visual inspection: remove the bottom cover with the battery and adapter disconnected. Look for a loose or damaged DC jack, lifted or cracked solder joints where the jack attaches, discolored or bulging capacitors, scorched areas or blown components near the jack area.
  • Measure at the jack and at the board: with the known‑good adapter connected, measure DC voltage at the laptop side of the jack (red to the jack’s positive, black to chassis). If the adapter’s jack shows the expected voltage but the board side of the jack or the nearby input pad shows no voltage, the jack, wiring or the input fuse is at fault.
  • Check the input fuse and traces: many boards have a small SMD fuse or fusible resistor immediately after the jack. Test it for continuity. An open fuse indicates a downstream short or a failed component; replacing the fuse is a low‑cost test, but only after confirming there’s no ongoing short.
  • Look for shorts on power rails: measure resistance between the input rail and ground (with power removed). A very low resistance suggests a shorted MOSFET/VRM component. In that case, board‑level diagnosis or microsoldering is usually required.

Common practical outcomes: a cracked/worn DC jack or its solder joints are frequently repairable (jack swap or reflow), an open input fuse is a cheap fix if no short remains, while a failed VRM or power IC usually means higher repair cost or board replacement. Take ESD and battery safety precautions; if there is any uncertainty about soldering or measuring live rails, a repair shop experienced with laptop microsoldering is the safest option. Combining the minimal‑parts isolation already suggested in the thread with these targeted board checks will usually identify whether the fault is an inexpensive jack/fuse repair or a full motherboard issue.

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Member Avatar for Techwriter10

Unplug it. Try pulling the battery. Then put the battery back in and plug it in again and see if that does it. I've had a couple of Vaios laptops over the years, and although it's been some time, I seem to recall resolving a similar issue in this fashion. Good luck.

Member Avatar for The STIG

Thank you sir for your responce. I did try that with no luck.

I was told a failed battery may cause this problem. But as of yet I have not ordered one. I want to be somewhat sure before spending $120.

Thanks again

Member Avatar for Techwriter10

Was worth a shot. After re-reading your original post it makes sense that it's a dead battery issue, and being a Sony, it's of course expensive to replace. Ah well, you have to do what you have to do. Good luck.

Member Avatar for The STIG

Got new battery and it did not fix the problem. It was worth a try. I guess I am going to have to cut a big check to get it fixed.

Thanks for all the info. I will post back when it is fixed with what the problem was.

Member Avatar for dgtllax

Got new battery and it did not fix the problem. It was worth a try. I guess I am going to have to cut a big check to get it fixed.

Thanks for all the info. I will post back when it is fixed with what the problem was.

I have the same problem, I eliminated the battery, and A/C charger. The problem is in the machine, apparently between the connection and the motherboard.

I was wondering what you did to fix this problem.

Thnx

Member Avatar for Technoslave

If you have already replaced the battery and power brick, then try removing the hard drive, optical drive, and one memory module, and see if it will boot to BIOS. If so, replace each removed componet one at time. Try powering up the machine after each part is reinstalled, until you find the part that is defective. If your laptop does not start after removing the parts listed above, you have a defective motherboard. Probably a blown capacitor.

Edited by Technoslave because: n/a
Member Avatar for k kiss

Hi Stig, were you able to resolve your problem? I am facing also exactly the same problem with my sony vaio e series. I already tried a new battery and charger. It still doesn't start up.

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