Few days ago, I found that my laptop is dead, I couldn’t switch it on. The power indicator (LED) is green, means the power is connected. But when I press the On/Off button, seemed it only responded 1-2 seconds then stop, nothing happen again.
What should we do to make it works again?
Well… I’m not the expert, and I’m not a technician. But here, I’m just going to share with you, how I can make my laptop back to work. So when you experience the same problem, I hope you will have the picture to have it on again.
There are 2 things need to be checked:
1. The adaptor
Check the voltage (I used volt meter / AVO meter). The gauge should indicate the voltage exactly the same as the figure mentioned in the adaptor.
In the adaptor case i read that the output is 19Volt, exactly the same as the volt meter tells me. So the voltage is OK.
Second thing need to be check is the Current. Because if the adaptor voltage is OK, but it cannot supply enough current, then it cannot make the laptop on.
Unfortunately, measuring current is not that easy. You need to put a load on and use the induction gauge. In my case, I skipped this. All I had to do is use this adaptor to another laptop with the same brand and type. If it works, then there is nothing wrong with the adaptor. And yes, I’d tested the adaptor to other laptop and it’s OK. SO I jumped to step no.2
2. The Laptop itself
If the power indicator LED is on, then it means that the laptop gets the power from adaptor (if it is off then you must check the laptop power supply!).
So.. the adaptor is OK, laptop receives power supplied by the adaptor. Why it’s still not on?
There must be a short circuit that makes an over load. We have to check the device which consumes lot of power, such as: CD/DVD drive, hard disk and fans.
How to disassemble laptop and take off CD/DVD drive and hard disk? Let’s jump to my next article, Disassembling Laptop for troubleshooting.
Monday, February 16, 2009
Tuesday, December 30, 2008
Using “EXISTS” makes query faster then using “IN”
There is an alternative way to substitute the using of “In” when querying SQL, which will make the process is faster and more effiecient.
Suppose you are going to get the information of all products which are included in promotion program:
“Select Product_ID, Produc_Description from Products Where Product_ID in (select distinct Product_ID from Promotions)”
The query will display all products from table Products which records are exist in table Promotions.
Now, try to replace “in” with “Exists”:
“Select P.Product_ID, P.Product_Description from Products P where EXISTS (select * from Promotions R where R.Product_ID=P.Product_ID)”
This last query will give the same result as the first one.
But if you work with huge database, the using of “Exist” will be more efficient compare to “In”, because using “in”, the subquery will read all data in table Promotions, then filter them uniquely using “Distinct”. After that, SQL Server will create a temporary table at tempdb for the subquery result, before they are used by main query.
The creation of temporary table, and storing subquery result into it, will make the process of main query suspended. And also, temporary table won’t have an index on it.
Using “Exist” for subquerying will be more efficient, because the subquery will be treated as a part of the main query … and thus, the result will be displayed faster..
Wanna try?
Suppose you are going to get the information of all products which are included in promotion program:
“Select Product_ID, Produc_Description from Products Where Product_ID in (select distinct Product_ID from Promotions)”
The query will display all products from table Products which records are exist in table Promotions.
Now, try to replace “in” with “Exists”:
“Select P.Product_ID, P.Product_Description from Products P where EXISTS (select * from Promotions R where R.Product_ID=P.Product_ID)”
This last query will give the same result as the first one.
But if you work with huge database, the using of “Exist” will be more efficient compare to “In”, because using “in”, the subquery will read all data in table Promotions, then filter them uniquely using “Distinct”. After that, SQL Server will create a temporary table at tempdb for the subquery result, before they are used by main query.
The creation of temporary table, and storing subquery result into it, will make the process of main query suspended. And also, temporary table won’t have an index on it.
Using “Exist” for subquerying will be more efficient, because the subquery will be treated as a part of the main query … and thus, the result will be displayed faster..
Wanna try?
Wednesday, December 17, 2008
Repair CDRom Drive
You might find, sometime, that your CDRom cannot read the inserted disc.
The disc can be read by other drive, but not yours. Means that the disc is fine, problem is at your drive.
Clean the drive head doesn't help. So... what are you gonna do?
Actually, before you take your CDRom Drive to the repairman, you can try to fix it by your self.
But... there is no guarantee that this action will fix the problem. It is all your risk.
What i did is:
- Take off the drive from the CPU or laptop
- But make sure before you shutdown the computer, the drive is remain open
- Unscrew the drive door, and take it off
- Find flexyble cable that is attached to drive head
- At that area, you'll find something like potensio or screw for trimming
- Using screwdriver, turn it about 10-15 degree clockwise (tighten)
- Put everything back on, and attach the CDRom drive to your computer
- Then insert a disc................ hopefully it works now ^_^
The disc can be read by other drive, but not yours. Means that the disc is fine, problem is at your drive.
Clean the drive head doesn't help. So... what are you gonna do?
Actually, before you take your CDRom Drive to the repairman, you can try to fix it by your self.
But... there is no guarantee that this action will fix the problem. It is all your risk.
What i did is:
- Take off the drive from the CPU or laptop
- But make sure before you shutdown the computer, the drive is remain open
- Unscrew the drive door, and take it off
- Find flexyble cable that is attached to drive head
- At that area, you'll find something like potensio or screw for trimming
- Using screwdriver, turn it about 10-15 degree clockwise (tighten)
- Put everything back on, and attach the CDRom drive to your computer
- Then insert a disc................ hopefully it works now ^_^
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