2 x Texas Instruments TI-99/4a Repair
Texas Instruments TI-99/4A Repair (#1)
Defect:
- Wave/Raster Lines.
Replaced parts:
- 1 x Variable Inductor 2 -> 4.5 μH (L100).
Gallery of repair:
Texas Instruments TI-99/4A Repair (#2)
I should point out that someone has already tried to repair, without success.
Defects:
- Black Screen (no raster, no sync) short circuit between 12v and 5v . . . and then . . .
- Wave/Raster Lines.
- Blue Screen with tiny Vertical lines and deafening sound.
- Garbage Screen.
Short Circuit Note:
- The short circuit was due to a malfunction of the IC: TIM9904ANL (U601)
Replaced parts:
- 1 x Variable Inductor 2 -> 4.5 μH (L100).
- 1 x TIM9904ANL (U601)
- 2 x MCM 6810P RAM 128×8 (U608 – U609)
- 1 x 74LS245 (U614)
- 1 x TMS9929 (U100)
Gallery of the repair:
Categories: Projects / Repairs, Today, Various
Hi !
Where I can buy this capacitor C101 12pF
I have only a small. I dont know how search it
@nameles
Hi Nameles, i have wrong to write in both repairs (now correct) this is a Variable Inductor 2 -> 4.5 μH (L100), you can choose the right one on this range.
This one work great:
http://www.ebay.com/itm/3-3uH-Inductor-Fixed-Value-Axial-Thru-Hole-Inductor-/122528196178?hash=item1c873fe652:g:9gkAAOSwlY1ZMHkK
example:
http://www.nightfallcrew.com/download/ti99-inductor-L100.jpg
Great !
I havent got a 3.3uH but I have only 10uH and I connect inductors in parallel.
Another TI-99/4a comes back to live.
THX !