Well, bears go to sleep in winters, but according to my blog activity, what we can know for certain is that I am not a bear. Let this ruminate in your mind for a while.
The fix that I will explain is for a Fujitsu Siemens laptop, not so new one... a PIII 1GHz, who's LCD suddenly went dark. The laptop did turn on, I could hear all the expected spinups, LED blinks, and managed to log on and hear the HD work... but no picture. I plugged in an external monitor and got the desktop. Diagnosis: there's something wrong with the LCD. There are usually two things that usually go wrong: a broken back light, or a broken inverter. The illumination of the LCD is similar to the fluorescent or "neon" lights as we call them in Europe. There is one very thin and very fragile fluorescent light usually mounted on the top of the LCD, and a "starter circuit" called an inverter. This inverter uses 12V and through some active electronics creates high voltage with low amperage that ionizes the neon and lights up the fluorescent lamp.
I had a similar problem some years back with a Compaq Armada M700. Then I opted out for a new inverter. That fix was $50, the price I paid for a second hand inverter. The Armada works perfectly fine till this day.
With the Siemens I had on my desk I could not immediately go for a new inverter because the owner was a poor student, so opting for a $50 solution was not really a solution for him.
So, I pulled out my UNI-meter, and started testing for current activity in the inverter circuit. The inverter boards are neatly divided in a low-voltage and a high-voltage part. The low voltage is on the side where the cable from the motherboard is connected to the inverter. This cable has at least 4 wires. The high voltage part is the one from which a two-wire plug gives out high voltage to the bulb. I started testing the low voltage segment. I found no activity, so I started testing the diodes and capacitors as the most probable causes for a malfunction. As I worked my way through the SMD's I ended up at the fuse, and to my surprise, that was busted. It turned out that the simplest of solutions was actually THE solution. The orange cube in the bottom left part of the photo is the busted fuse. It is a 1.6A fuse.
After finding the broken component, now I had to replace it. Since I am a student too and do not have a full size workshop with all the components I would ever need, and I had to keep the expenses for repair to a minimum (meaning no expenses at all), I decided to find an appropriately thin wire and bypass the busted fuse. You can see the wire going from the left of the fuse all the way to the right... it looks like a silver arch resting on the printer board. This is a very very thin wire, the thinest I could find in my room. I had to make sure that the wire both bypasses the fuse, and is just the right size so that it would not break when the LCD is on, and at the same time not too thick so that if the circuit overloads the wire would be the first thing to break. The fuse itself looks quite big on the photo, but its actual size is about 5mm length, so it was a tedious job to solder the piece of wire. For an old laptop, fixing the inverter is probably the best option since its market value is not much higher than what he would pay for a new inverter.
If you find my blog posts helpful please consider a small donation.
Let your friends know about this blog post
3 comments:
Hi Mr. Mateski, ur post about this LCD is interesting to me. I've some what same problem with my old lappy of IBM ThinkPad, very old, which is Pentium 2. Well, the problem is when u turn the laptop ON, the LCD screen displays the picture but it blinks on n on and after some seconds it goes blank. And if u press Fn+F4 for the external display switching shortcut key, some times the displays comes up without any blink. But most of the time it doesn't work. Ok, so i hope you are clear with my problem in LCD. Well, can u tell me what might be the defect on the circuit component? I hope to troubleshoot the problem with your help. Hoping to hear you reply soon.
Hi Mr. Mateski, ur post about this LCD is interesting to me. I've some what same problem with my old lappy of IBM ThinkPad, very old, which is Pentium 2. Well, the problem is when u turn the laptop ON, the LCD screen displays the picture but it blinks on n on and after some seconds it goes blank. And if u press Fn+F4 for the external display switching shortcut key, some times the displays comes up without any blink. But most of the time it doesn't work. Ok, so i hope you are clear with my problem in LCD. Well, can u tell me what might be the defect on the circuit component? I hope to troubleshoot the problem with your help. Hoping to hear you reply soon.
@ the IBM owner: I'll research this issue and let you know in the next day or two. From what you're telling me, it may be either a bad contact or a bad capacitor... but it's hard to say. Let me know what the model is and if you remember how this problem appeared: did you have the lappy on for a long time, or was it off for a long time, any power surges... anything out of the ordinary. Also, does this happen during the bootup sequence, or while in DOS, or this flicker happens only in Windows? Sometimes there may be a graphics dirver issue, so it's safer to start from software issues and work toward hardware. Anyway, let me know of as many details as you can and we'll work toward a solution.
Post a Comment