Saturday, April 24, 2010

8 feet - home made C band satellite dish antenna

In this project we design 8 feet C band satellite dish antenna and some of its specifications are listed in below,

  • Diameter of the reflector : 248.0cm
  • F/D ratio : 0.391
  • Focal length : 91.5cm
  • Calculated gain (Aprox.) : 40.23 dB

  • Materials used for reflector : Aluminum sheets and Aluminum nets
  • Number of panels (in reflector) : 4 units
  • Materials used for Mounting mechanism : Steel
  • Weight (Aprox.) : 40 - 45 kg (without antenna positioning system)

  • LNBF : Generic dual twin C band LNBF
  • Antenna positioning system : Using D.C motorized actuator

Monday, April 12, 2010

Repairing Sony PlayStation 2 Game Console

One of my friend had Sony PlayStation 2 (SCPH-39000 series) game console and in few months back it get fail because of the internal short-circuit due to spill of some liquid over the game console. Finally he sends it to me to repair it, and I found some problems in both PSU (Power Supply Unit) and motherboard of the console.

In first round of the repair I replace IC807 (78M05), PS013 fuse and all the related parts near that area (because I notice some burn marks in that location) except IC806 (NJM12904). Other than that I replace R278 (1.5k), R279 (1K + 100R), R491 to R495 (with wire links), R470 (100K), Q415 (2SC2873), Q406 (IRF7901, I got this transistor from another old PS2 game console main board, available in junk store), F001 (with some 42 S.W.G copper wire) and D404 (with 3 × 1N4148 diodes).

When I replace and re-solder some of the parts as described above, I got the video signal (PS2 startup splash and main menu) from the console. But system may not produce any audio signals (in both left and right channels of audio output). Finally I check the audio part of the system and found that the problem is in final stage of audio DAC (IC517 - Cirrus Logic CS4335 - 24-Bit, 96 kHz Stereo digital to analog convert chip). Once I replace that chip (thanks to old PS2 game console main board which I was purchased from the junk store) this system may get start with both audio and video.

Once the system is up and running I attach the battery and other assemblies to the board and finalize the repairing process.

If someone like to repair Sony PlayStation 2, following points are important to him/her (according to my experiances),
  • Before make any repairs, disconnect the mains supply and battery supply from the main board.
  • Make sure to place insulations sheet between the PSU and Shield B (Shield located at the bottom side of the main PCB).
  • Most of the components of main board are SMDs. So it is necessary to have good SMD Rework Station to carryout any component level repairs.
  • There are several flexible ribbon cables in this system. Handle them with proper care.
  • Do not adjust any potentiometers, trimmers and coils located on the main board, PSU and Optical Pickup.
  • There are several heat transferring sheets are located on the bottom side of the main PCB. (e.g : heat transferring sheets attached to the IC802 - BA5815 and IC803 - BA6664). Make sure to attach them properly when setting up the Shield B.