2 x Texas Instruments TI-99/4A Repair
Gallery of the repair:
Texas Instruments TI-99/4A Repair (#1)
Defect:
- Blue Screen with tiny Vertical lines.
Replaced parts:
- 1 x MCM6810P (128 x 8-Bit Random-Access Memory TTL/DTL)
Texas Instruments TI-99/4A Repair (#2)
Defect:
- Blue Screen with tiny Vertical lines.
- Wave/Raster Lines.
Replaced parts:
- 2 x IC MCM6810P (128 x 8-Bit Random-Access Memory TTL/DTL)
- 1 x IC CD3236A-NL (ROM)
- 1 x Capacitor 12 pF.
Note:
In one photo you can see the curious change made in this TI-99/4A by inserting a resistor in the pitch where in other motherboards is soldered a leg of a electrolytic capacitor and then one leg of the capacitor is welded and the not the other leg. Compliments.
Video of the defects:
Categories: Projects / Repairs, Today, Various
Well done on your work.
Do you know if the TI 99/4A board has over voltage protection on the 5v input on the motherboard? Example if power supply feeds more than 5v instead of 5V on the motherboard due to fault in the Power Supply, would the TI 99 4A motherboard regulate it (burn a fuse etc…) or will it leave all the voltage to fall on the Chips (VCC) ?
Thanks