Savel brain dump in English!

Transferred from old and some-why Google banned pages.

Chip, PCI/AGP/ISA/MCA/CPU and etc. slot desoldering from PCB board

After lots of experiments of desoldering multipin parts from PCB using fancy irons, gas torches, hot air guns and other stuff I “invented” this technology. Using this technology all parts do not get mechanical stress and PCB board is not damaged. This method is ideal for multilevel PCB. I didn’t find any damage to parts caused of using this technology. The only bad side of this technology that ALL parts are desoldered. It is impossible to desolder selected parts.
This technology is free for personal use. If you want to use this technology in industry, please contact me as it is © by Levas. 🙂

Preparing: Remove all jumpers, batteries, socket-ed parts. Also remove all plastic mounting devices used to fix board in casing. Check solder side for bent pins. Prepare grill grid and few vials for collecting fat. Better use 3 ones. One in oven, two other on floor.

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I was asked to switch load using computer’s COM port (RS232). At first, I was thinking, that I need to switch some lamp or heater, so I offered to use solid state relay and forget all the electronics. But later, I was explained, that I need to manage wireless access point connected to router. As the access point tends to hang-up the administrator need to reboot it. Automatically from linux router script.

I offered simple variant- use the mosfet. Here is the first version of the device in mine breadboard… somewhere in this image. 🙂

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At last I received my MSP430 development kit. The problem is, that Texas Instruments didn’t know geography and they didn’t discovered new EU countries. So, my parcel moved to Lichtenstein instead to Lithuania. So I invested 34 devalued US dollars and received some small items:

The print on the box says: MSP430 Ultra-Low-Power MCUs eZ430-F2013 Development Tool. There is CD and small USB device inside the box. The CD is with neutered software. The C compiler is limited to 4K!. The USB device is special development tool with small daughter board with F2013 micro-controller.

For now I didn’t made anything useful from this stuff. The software is not very user friendly. The example code is very small (on the cd) , only some blinking LED. I downloaded more examples for TI website. When I’ll find some spare time, I’ll examine it more.

USB device can be opened. So you and attach some wire to inside board or change daughter board. Windows XP detected this device as multi-port adapter and installed drivers from TI CD.

Blog post for information only.

In trash pile I found something strange. It was like spot light and pizza box hybrid. Inside lamp box I found some wireless stuff- some controller, PCMCIA wireless LAN card and PSU. The pizza box was antenna.

Wireless LAN PC Card, Simple mobility NL-2511CD Plus EXT2 (High Power (23dbm) Conexant/Intersil PC Short Card-NL-2511CD)
Controller based on Axis Communications CPU without any significant prints on silk screen. Some sticker with MAC address. LAN connection and power in slot. Three LEDs: power, LAN and Wireless.

Other PCB is power supply and PCMCIA adapter.

Antenna made in Israel: MARS Antennas & RF Systems Ltd.
MA-WA24-1X PM

After some investigation I discovered that few years ago one wireless internet providers used such devices for end user points. Now these devices are almost obsolete.

Sometimes it is great need to weld some metal sheets together. Sometimes they are very small, like nickel plated battery connectors. There are special industrial devices for spot welding, but for DIY and hobbyist user it is very easy to build this welder at home.

All you need is few very big capacitors, thick wire and DC power supply. Sometimes you need to put some resistance in such device, and automotive headlight lamp is very good alternative. The PSU must be as powerful as possible. Output voltage must be less than maximum voltage of capacitor and safe to handle.

Circuit diagram of the spot welder is something like this:

In my experiment I used 3 capacitors 100 000µF at 16V each. It is recommended to use variable output power supply to change the welding power. Too much power may make holes in your battery pack. Before welding useful device make some practice on some bad cells.

Here is my experiment with steel tape-like detail from digital photo camera. It is about 0.25mm thickness nickel plated steel. Double spots made connection quite durable. Never use single spot- it tears of very easy. For battery packs prepare special nickel plated or pure nicker foil. As simple steel or copper will corrode in time.

Magnified welding spots:

Just short blog post. The Relisys RWT205CE terminal I received was not working. The problem was classic- fault of the power supply. Just replaced few blown capacitors and everything is working fine. As I replaced with bigger caps, the small heatsink is bent. But it is working fine.

Originally this terminal computer is equipped with Windows CE operating system. And it is designed to work with some server. This terminal is based on i386 based SIS made CPU. RAM- mini dimm, 32Mb. Compact flash card (CF) placed instead hard disk. The card is hardwired to IDE interface using simplified connection. So the master/slave stuff is not working. It is big problem while trying to install other system using CF and CDROM. Other connectors: USB, LPT, COM, PS/2, PCMCIA, CF, IDE, Audio, VGA, PCI and some other unknown.

Main idea while playing with this computer- to install Linux OS and make something like router with advanced options like: data collection from external interface, USB web Cam translation.

After lots of experiments, I only managed to put freesco image to CF card. The problems were booting from the CF card is it was formatted with Windows XP OS. Just only when I reformatted the card using old Epson digital camera.

I managed to boot mini Debian install and it detected USB device, so I managed to add some other images to install.

Some problems with PSU. Or maybe it is normal- but I didn’t managed to configure the device to start after power failure. It is mandatory when using this terminal as fan-less computer or network router. Now after power on I get only blinking LED and no cold boot.

Today I decided to break apart few bluetooth headsets. I have 3 models, all made by Logitech. Most of the headsets have same, typical damage- the mic wire is broken. The problem is even described in manufacturer’s webpage. Just if you turn microphone around the headset and use some force, it breaks very small stopper and turns around. And small wire from main PCB to mic is broken.

I tested the devices with my old Nokia phone and computer using microsoft usb bluetooth adapter from mouse and keyboard. Computer detects Logitech headset, but didn’t install the “audio device”. In Logitech pages the problem is described like: “normally all devices are installed automatically”. And not a single word about “abnormal” situation. I think it is microsoft fault- microsoft bluetooth stack is lacking some “standard” elements. You need to install Widcomm drivers.

Inside the headset is nothing interesting…

On the other side of PCB is only quite big Liion cell and contacts for charger.

Main element in the headset is CSR semiconductors chip. It is MCU, DSP, audio device, bluetooth in one chip. On the right, emphasized PCB you can see something like EMI shield, but I thing that it is only some leftover from some bigger shielding.

Other components are only for charging, LEDs management and audio amplifiers.