Savel brain dump in English!

Sometimes I try to fix LCD monitors and I have some leftover LCD modules from various LCD monitors. I place then in various spaces to prevent screen from scratches. I noticed one LCD module on my windows and I remembered one gad how to convert LCD monitor to video/computer overhead projector. So I disassembled the LCD module, removed all plastic and metal part. Now I have only the glass module with some chips glued to it. It is (I think) Chungwa 17″ module from Samsung monitor (Yes, not all Samsung monitors are made by Samsung). The LVDS control chip is made by Novatec. The matrix have some flaw typical to this Samsung model- white horizontal line and all image disappear after some time. The problem is in the row decoder (counter) chip. One chip is very hot and when it overheats, whole screen is switched off. The switched off LCD screen in transparent.

You can see bad chips on the side of the screen. In this photo it is in the top the image, as LCD module is rotated.

You can see, that LCD module is transparent. The photo is not very good, that you can imagine, that light can go threw the screen.

Continue reading →

I have Thrustmaster LCD in my LCD collection for more that one year. The exact model is: XL Screenmate. I was trying to sell it in my online shop, but nobody was interested. Our local electronic hobbyist are not very open minded and still stuck to smaller projects.

After some digging in the internet I found some pinouts and example schematics how to connect this LCD to analog RGB source with standard TV timing (PAL or NTSC).

I connected to Philips DVD player as it is easiest way to find analog RGB source with 50Hz/15kHz timings. It is possible to connect it using scart connector, but I don’t have male scart connector in my stock. So I connected directly to may PCB of the player.

The image is a bit dark. Maybe it is old technology LCD matrix, or maybe the RGB level is too low. Also, the power supply of the DVD player is to weak to drive this screen. Original connector is labeled 7.5V with internal regulator in LCD screen. On RGB connector is +5V pin, but I never tested it. The DVD PSU has 5V and 12V output. When connected to 12V the PSU become very hot- it was overloaded. So if I want to integrate this screen to DVD player box I need to install more powerful power supply. In fact, current power supply is to weak to drive even the DVD player. When player starts to spin the disk, the image gets darker- it seams, that PSU is lowering all voltages- some sort of brown out.

Here is closer look to the device. That ugly green plastic is already removed. I just was too lazy to make new photo for this web log.

Continue reading →

Somehow I received “several” bad Philips DVP 3010-02 DVD (DivX/Xvid) players. They were sold in local market about year ago for about 100$.
All the devices have same flaw- not reading disk due to the damage of flexible conductor. This is design error. I think Philips must pay me some money for discovering such errors 🙂

First off all, the only thing from Philis is brand name sticker on the device and few bitmaps in firmware. It is generic DVD player with Mediatek processor. It is same CPU as in VIDO player (and many other). Disk reading device is made by ASATECH.

To repair this player just open the box, remove disk holder and look to flexible conductor. If one end, near laser is bended to sharp angle the problem is located. All you need is to change this conductor… or just spend some time and repair it.

In this image you can see the broken part of flexible pcb. Also, when removing the conductor, remove some scotch tape holding it. This tape is placed in wrong place- there is very small room to flex pcb. If the tape was glued near the main PCB, the player would be working without any problem.

In this image you can see where the flexible conductor was glued (1) and the place were it is broken (2).

Here is the image of repaired device. The conductor is glued in other place, so it can curve in lots of space. Some players were with special pcb holder, but the flaw is the same.

To fix player you need:

1. Screwdriver “star”
2. Screwdriver “philips”
3. Scissors.
4. Some Scotch.
5. Good thermoregulated iron (if you want to fix pcb instead of buying new one)
6. Some other tools and steady arms.

Here is software, source code and excel worksheet to check citizens personal identification code used in Lithuania. Checking the code is mandatory when filling various legal documents.

Here is the checker as independent MS Visual Basic program. As I have only old version of the basic, the software is not Unicode compatible. Download ID checker software.

The program may require MS Visual Basic runtime. You can download it at MS web site.

The algorithm is very same. It can be ported to any other programming language:

Backslash “\” means the you don’t need to break line.

Private Function chksum(ak)
Dim c, c1
c = Val(Mid$(ak, 1, 1)) + Val(Mid$(ak, 2, 1)) * 2 + 
\ Val(Mid$(ak, 3, 1)) * 3 + Val(Mid$(ak, 4, 1)) * 4 + 
\ Val(Mid$(ak, 5, 1)) * 5 + Val(Mid$(ak, 6, 1)) * 6 +
\ Val(Mid$(ak, 7, 1)) * 7 + Val(Mid$(ak, 8, 1)) * 8 + 
\ Val(Mid$(ak, 9, 1)) * 9 + Val(Mid$(ak, 10, 1))
c = c Mod 11
c1 = Val(Mid$(ak, 1, 1)) * 3 + Val(Mid$(ak, 2, 1)) * 4 +
\ Val(Mid$(ak, 3, 1)) * 5 + Val(Mid$(ak, 4, 1)) * 6 +
\ Val(Mid$(ak, 5, 1)) * 7 + Val(Mid$(ak, 6, 1)) * 8 +
\ Val(Mid$(ak, 7, 1)) * 9 + Val(Mid$(ak, 8, 1)) * 1 + 
Val(Mid$(ak, 9, 1)) * 2 + Val(Mid$(ak, 10, 1)) * 3
c1 = c1 Mod 11
If c <> 10 Then
    chksum = c
ElseIf c1 <> 10 Then
    chksum = c1
Else
    chksum = 0
End If
End Function

Private Function ak(s)
Dim i
i = chksum(s)
If Mid$(s, 11, 1) = i Then
    ak = True
Else
    ak = False
End If
End Function

The source above as text file.
And here is the same software in MS Excel sheet. Don’t forget to adjust security setting to allow running macros and visual basic commands.

There is special term- memory leak. What it is? Looks similar to brain leak, or that old joke from old zombie movie: brains brains…!

In real world, the bug in memory management is described as memory leak. Every program use some memory (RAM, Video RAM, virtual RAM) to store some data. In modern operating system, program must request from OS for some memory. After using it, the program must release the memory. But there are bugs in software, and sometimes requested memory is a bit more than released. There is not a big problem, if the program is working for a short time- after the termination of process, all allocated memory is released (unless the OS have memory leak itself). But some software is running all the time computer is on. Especially in servers, where uptime is calculated in days, months and even years.

So, one buggy piece of software is Bittorrent client. Here is the result after running it for some days…

This image is more informative… 1.3Gbytes (!) of RAM is quite many for background file transfer.

I was forced to build some VPN (virtual private network)… I examined all my available documentation, did all RTFM and consulted with some gurus from local unix newsgroup.

I selected first available VPN type: PPTP. I am using Linux Debian stable on local servers. As server is running for a long time, the system was “old” stable version. So simple command “apt-get install pptd” didn’t work. There were lots of problems and missing components. So I selected other method- in some trash I picked up old Fujitsu Siemens computer. It very small, pizza box size computer with Pentium III cpu with integrated video, lan, sound and etc. I added two additional realtek ethernet boards to make “router” look cooler. If everything will be working fine, I’ll transfer stuff to real server.

Here are just illustration: screenshots of WindowsXP VPN configuration screens.

I downloaded and installed latest stable Debian. It was “etch”. All devices were installed without any problem. I installed only “base system” as I like to install all needed stuff by myself.

apt-get install mc iptraf lynx ssh

I like these programs, so I installed them. Especially “mc” as I love old style, norton-alike file manager.
Continue reading →

From time to time I repair computer. Sometimes it is just software problems, sometimes- hardware. But some times it is dust problems. Dust full computer appears on my workbench very often, but I don’t have my digital camera nearby to take a picture. Sometimes I open computer cases at client’s home and I don’t want to take pictures…

But here is few pictures of real computer I repaired and short description of the problem:

This computer “was running quite fine, only few sudden reboots in a day”. 🙂 But when weather temperature raised because it is summer now, computer’s reboot become irritating and owner brought it to me.

This video card was working fine. No reboots or freezes. But how much dust it need to collect to stall GPU fan?

This Athlon sometimes freezes the computer. Especially when encoding video. Do you know why?

This video card (Radeon X800) was big secret for owner. He can’t start video games. Few months ago all games were working fine, but after some time he could not start any game. In “2D” mode, you can use computer for weeks! We tried newest video card drivers, chipset patches, even reinstalled windows few times… I only removed dust clog and everything is working.

I was browsing in Internet for some information about LCD programming. It was regular web page about some bugs in LCD software. Suddenly I noticed that my CPU fan is running very fast, case rear fan started too I and can feel hot air passing from my computer. I tested CPU load and noticed full load from internet explorer! As my system is with dual core, the whole load was only 50%, but it is too high for simple web page with three (!) animated gifs. Here is the URL to this strange web page:http://www.lcdstudio.com/forum/viewtopic.php?t=10684

I have special utility to read date from my APC UPS. According to it (see the screen shots), my computer consumes about 267W of energy when showing simple animated gifs. On the right side image there is snapshot of “idle” computer- only Outlook express, Photoshop and other background stuff. So Microsoft is using up to 76W just for displaying some animated gif! BTW, firefox didn’t use any extra watt for this web page- the CPU load is zero.

(Two images on one place.)

Here is screen shot of idle computer (google webpage display):

And here is mystical load when looking to animated gifs. I have dual core, so one core is idle. I tested this page at my workplace and single core computers were loaded to 100%.

Maybe Bill will fix it? I have some reports that new Vista windows have same bug. If you want to test this page, please set that this web page is displayed with all images visible, IE windows active. Please wait for a while to get full result- CPU load grows after some time.

I disassembled few batteries from notebook computers. There we some “economical” versions among them. Such “lite” versions are typical for “sales” version of computers- when the price is in matter. In notebook datasheet all working times are for normal batteries and with “no load” situations. When you buy computer on “sales” event, you’ll receive “light” version of batteries. Here is few photos of open “lite” versions of batteries with small description.

Here is the 14.8V, 2000mAh version. Normal version in same box is 14.8V, 4000mAh. The capacity is halved. 30Wh versus 60Wh.

Here another version of lite cells. Our days the notebook computer’s hardware can work from “any” voltage. Switching power supply can drain power from any type of source. So, here is another version of lite batteries. User may learn to calculate capacity in mAh, but energy is stored in Wh. So we can leave SAME capacity, but reduce voltage a bit. In the top: 11.1V, 4000mAh battery. This means only 44Wh versus normal 60Wh.

Lower one is typical low capacity version with reduced Lion cells. Here is only some mystical high precision capacity 2000 v.s. 2150. The 7.5% means many when counting length of … 🙂 but when it is capacity, this means nothing. They use special plastic tube spacers to reduce Li-ion cell wobbling in battery.

Both batteries have identical bodies. The marking on the battery is good. The manufacturer didn’t lie here.