RobertCX
SGS Nanocomputer - fully restored and working
Here is my SGS Nancomputer fully up and running, showing the keypad/display test program (all segments lit). The apparent marks on the display filter are actually a reflection of my ceiling!
This board has required a lot of effort to fix, specifically:
1) Shorted tantalum capacitor on main board between +12V and -12V rails.
2) Disintegrating IDC connector to the keypad/display.
3) Faulty drive transistor in the display module, fixed by neatly bodging in aseparate PNP transistor.
4) Dodgy connections and bad capacitors in the PSU.
I also inserted a plastic sheet to insulate the PSU board from the bottom of the case, just in case a solder joint was too close. And I also added plastic sheets between the backs of the PCBs and the ribbon cables, to prevent potential damage to the ribbon cables from the sharp component leads. I had to use an extender cable on the keypad ribbon cable, because I had to fit a new IDC connector (thus shortening the cable), and the original cable was only barely long enough.
The board also came with a perspex cover sheet, but this is not currently fitted, as I have a 2816 EEPROM chip mounted in a ZIF socket, which would foul it. Once I have finished software development, I will fit a permanent 27C16 EPROM and then refit the perspex cover.
SGS Nanocomputer - fully restored and working
Here is my SGS Nancomputer fully up and running, showing the keypad/display test program (all segments lit). The apparent marks on the display filter are actually a reflection of my ceiling!
This board has required a lot of effort to fix, specifically:
1) Shorted tantalum capacitor on main board between +12V and -12V rails.
2) Disintegrating IDC connector to the keypad/display.
3) Faulty drive transistor in the display module, fixed by neatly bodging in aseparate PNP transistor.
4) Dodgy connections and bad capacitors in the PSU.
I also inserted a plastic sheet to insulate the PSU board from the bottom of the case, just in case a solder joint was too close. And I also added plastic sheets between the backs of the PCBs and the ribbon cables, to prevent potential damage to the ribbon cables from the sharp component leads. I had to use an extender cable on the keypad ribbon cable, because I had to fit a new IDC connector (thus shortening the cable), and the original cable was only barely long enough.
The board also came with a perspex cover sheet, but this is not currently fitted, as I have a 2816 EEPROM chip mounted in a ZIF socket, which would foul it. Once I have finished software development, I will fit a permanent 27C16 EPROM and then refit the perspex cover.