This computer is of a dear friend; Paolo Cognetti.
Short story of the repair:
I have checked the voltages and are correct, although a couple of capacitors on the power stage need to be replaced.
I have tried to turn on the computer and i have see immediately a problem, the screen is full of random characters, with the oscilloscope i have tried to see if i have data stream on the CPU (Z80), interrupts and so on.., nothing, it seemed completely dead, replaced.
The computer has started better then before but with some video glitches, raster lines scrolls from bottom to the top and some characters scattered on the screen. I double checked the voltages and i have realized that the 12v are gone and the 7812 warmed a lot, about 80 degrees after 2 minutes.
Almost all tantalum capacitors of 1uf and 33uF on the 12v line are shorted, i have decided to replace them all (22 pieces)
After the replacement of all tantalum capacitors and two electrolytic capacitors on the power supply stage the computer has started to work correctly but with some video problems, characters scattered on the screen, after replacing two Static RAM 2114 everything works perfectly, including the Basic Cartridge that until now had never worked.
Works that have been made:
- Fixing broken Fuse Holder.
- Fixing a cold welding of a capacitor on the power supply stage.
- Testing Voltages.
- Replaced CPU Z80.
- Replaced 12 x Tantalum Capacitors (1uf)
- Replaced 10 x Tantalum Capacitors (33uf)
- Replaced 1 x Axial Electrolytic Capacitor (470uf)
- Replaced 1 x Axial Electrolytic Capacitor (1500uf)
- Replaced 2 x NMOS 2114 Static Ram.
- Fixed the botton cover with two missing screws.
- Cleaning the top cover using only water and a sponge.
Exidy Sorcerer II Repair Gallery:
Exidy Sorcerer II Gallery: