Fixing a Radio Shack TRS-80 Model 1
This is a little description of the repair of a Radio Shack TRS-80 Model 1 for a Friend.
The computer comes with several problems.
- Some IC are dead or in shorted state.
- Keyboard flat cable.
- One key “L” is dead.
Finding the cause of the fault has not been easy, i had to ask for a help to Ian, this dude is an expert of TRS-80 repairs.
How you can see from the photos, i had to replace a number of IC.
- 4 x Video RAM 2102 (Z62 / Z63 / Z46 / Z48)
- 1 x Z80 (Z40)
- 1 X 74LS157 (Z31)
- 1 X 74LS93 (Z32)
Stage of the defect (before and after):
Keyboard repair (replacement of internal contacts):
Micro Computer Technical Reference Handbook: