Radio Shack TRS-80 Model 100
The TRS-80 Model 100 is a Tandy Corporation 8-bit portable computer released in 1983. It is actually a rebranded Kyotronic 85 designed and produced by Kyocera for the Japanese computer market. It was a very successful model for Tandy, selling over 6 million units, no doubt due to its compact & portable size, excellent keyboard, built-in modem, and the fact that it runs on standard AA batteries.
- For more information, see this article's corresponding Wikipedia page: Device.
| Preliminary Information | |
|---|---|
| Release Year | 1983 |
| Leak Risk | Medium-High |
| Batteries | Four (4) AA, 1 NiCd (3.3v) |
| Mounting Technology | Through Hole |
| Capacitor Types | Aluminum Electrolytic, Tantalum, Ceramic, Polymer |
| Destructive Entry | No |
This is a template page for creating new pages for devices, troubleshooting them, part lists, and other repair info.
Known Issues
Leaking NiCd Battery
This is a very typical issue on the Model 100 and its variants. The NiCd batteries, if still installed, are very likely to have leaked after nearly 40 years (as of 2022). The originally installed NiCd is usually a Yasua 3-51FT-A 3.3 volt, at least in USA variants. It is soldered by its legs to the motherboard, 1 leg on each side of the battery. When it leaks, it tends to spread across the board and infect other components while corrupting the board screening and etchings. These batteries are surprisingly good quality, however, and some of them still function normally all these years later. Either way, to avoid damage to the circuit board, any original NiCd battery in the Model 100 should be immediately replaced.
Causes
- Age. These batteries were not meant to survive beyond a few years. Most owners of Model 100s never replaced these batteries, as the skill needed to do so would have been beyond that of a normal user.
- Long-term exposure to humidity or higher than room temperatures would most certainly hasten the breakdown of the battery's shell and internal chemical composition.
Solution
- While it is possible for the Model 100's original NiCd batteries to still work seemingly fine all these years later, they should be replaced immediately.
TBD: the process of replacing the NiCd.
Won't Power On - Low Battery Light Flickers
With fresh batteries or
Causes
- Usually leaking capacitors
Solutions
- TBD: replacing the caps
Symptom or Problem Encountered
Causes
- Description of cause
Solutions
- Solution to the problem
Disassembly Notes
Warnings or tips to disassemble the device
TBD: go through a photo-based teardown.
Original Parts
Basic PCB Name (call out all the variants)
Note model numbers and board revisions here
| RefDes | Qty | Capacitance | Voltage | Mount | Diameter/Size | Height | Lead Spacing | Temp | Type | Brand | Series |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 µF | 0 °C |
Replacement Parts
Basic PCB Name (call out all the variants)
| RefDes | Qty | Compatible Part Number | Order Links |
|---|---|---|---|
| Digikey |
If parts are not available or different selection is preferred, you can use the values in the Original Parts section to perform a parametric search.
Kits
- Digikey BOM: https://www.digikey.com/