Sony VAIO Dead, MBX 196 Motherboard Fuse?


Jun 17, 2012
Hi, I have a SONY VAIO VGN CS190, with a MBX 196 motherboard.

I suspect that something has blown on the motherboard. On connecting the AC cord, I get one light (the long green light by the front; not sure what it's supposed to be for other than decoration), and the battery light in orange. There is absolutely no other light, no noise, no activity, nothing on the screen. Power on button does absolutely nothing.

The long story:
The DC power jack was extremely loose. Turns out it was broken. I got a new piece and soldered it.

Quick test showed that some lights were coming on, so I closed the laptop with all the screws. On plugging the cable from the AC adapter, I got sparks by the jack. On opening the laptop, I saw that the jack had moved inward, causing the positive terminal to touch somewhere in the chasis, causing a short. The ac adapter blew.

I got a new adapter and fixed the jack so it would not move. Now, as I wrote above, on connecting the ac cord, I get the long green light, and the battery light, before I press the power button. Absolutely no other sign that the laptop has power; pressing the power on button does absolutely nothing. Definitely no fan.

After reading many forums, I have tried a few things such as taking the battery out and trying with just the ac cord, reseating memory etc.

Looking for a fuse, or anything else near the dc jack that might have blown, I got a schematic diagram for MX 196, 32 pages long.

I can't even tell where the wire from the dc jack is supposed to go on the diagram.

Is there a fuse on this motherboard? The way the short I think happened, the AC adapter blowing makes sense, but I would have thought that the motherboard would be ok.

I see a small circuit board (around 2 inches by 2 inches) that sits on top of the main motherboard, where the wires from dc jack go...presumably the power supply unit. There is continuity from the DC jack up to the point on this circuit board where these wires go. Beyond that, I am at a loss to troubleshoot.

I can't see anything that looks like a fuse. Nothing marked FS or F or fuse. Nothing appears burnt, damaged.

What could have blown? I have a multimeter and decent (somewhat thoeritical) knowledge of electronics, soldering etc, and the patience to spend a few days before writing this laptop off.

Any tips on troubleshooting?


Jan 27, 2013

Did you ever get to the bottom of this? find a fuse etc.

I have a very similar symptom. I had changed the hard drive done a recovery and 104/127 updates, shut down letting he update installations complete. Had some sleep went back to the laptop in the morning to continue and it would not boot. Gree light yes, brief apparance of the HDD Led as disk presence was checked and that was that nothing appears on the screen , no vaio logo, no attempt to boot.

cussing quite alot now.

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