PPI Super Sketch for Texas Instruments TI-99/4a
PPI Super Sketch for Texas Instruments TI-99 Repair.
Defect:
- The cartridge is not recognized by the TI-99/4A.
Repair:
- Replaced 1 x 74LS139 (U1)
- Replaced 1 x 74LS30 (U2)
Note:
The repair of the Super Sketch cartridge was quite simple, in the first time i thought a problem of the ROM but instead the failure was the two IC U1 and U2, which should do the work of the Bank Switching.
To remove the two IC i have preferred to cut the pins and then remove each pin because i know very well this type of PCB and also lowering the temperature there is a risk that the pitches come off.
Gallery of the repair:
Categories: Projects / Repairs, Today, Various
Thanks for the information. I know of 1 that does not work. I have one myself, have to take it out of storage and test it. You have saved me much frustration.