Tandy Radio Shack TRS-80 Data Terminal (DT-1) Repair
Tandy Radio Shack TRS-80 Data Terminal (DT-1) Repair.
Defects:
- Some keys are dead (X – Z – DEL – ])
- Sometimes the characters typed are uppercase and sometimes lowercase.
- The DT1 Terminal doesn’t turn on the first try.
- Horizontal scan problem. The right side of the image is rolled up on itself.
- Outside ground of the CRT disconnected.
The jobs that have been made:
- Replaced 1 x 74LS138 Demultiplexer (U1)
- Replaced 1 x 74LS240 Octal Buffer/Line Driver (U23)
- Replaced almost all capacitors on the power supply side with the wrong ESR/Capacitance.
- Cleaning keyboard switches. Fortunately these switches can be opened.
- Removed the filter capacitor (RIFA)
- CRT Linearity adjustment.
- Restored the outside ground of the CRT.
Categories: Projects / Repairs, Today, Various
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