Mattel Computer Chess Troubleshooting Guide
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Fault-finding on the Mattel Computer Chess pocket chess computer (model 1992, 1980). No service manual, schematic or repair write-up has been published. What follows comes from Mattel's controls drawing and MAME's notes on the hardware and on how the program behaves. Batteries and care are covered on Mattel Computer Chess General Maintenance.
What a working game does
[edit | edit source]- Switched ON, the LCD shows the chessboard and pieces.[1][2]
- P VS M, M VS M or P VS P chooses the kind of game; LEVEL sets the strength from 1 to 4.[1]
- The direction keys move the cursor; MOVE selects a piece, or asks the computer to move; ENTER MOVE completes the move.[1]
Things that are not faults
[edit | edit source]| What you see | Why | Source |
|---|---|---|
| The game makes no sound | There is no sound hardware | [2] |
| There is no key to start a new game | Switch off and on again (with the switch not at SAVE) | [2] |
| An old position appears at switch-on | The switch was left at SAVE, which keeps the position in the LCD chips' memory | [2][1] |
| The saved game came back at a different level | The level setting is not saved | [2] |
| A game saved with SAVE was lost | CLEAR must be pressed before switching to SAVE | [2] |
| Black moves first | COLOR was pressed: it lets Black move first | [1] |
| The cursor has gone | CLEAR erases the cursor during a game | [1] |
Symptom table
[edit | edit source]| Symptom | Probable cause | Action |
|---|---|---|
| Blank display at ON | Flat or reversed cells; corroded battery contacts; dirty switch | Fit four fresh alkaline AA cells the right way round; clean the contacts; work the switch. See Mattel Computer Chess General Maintenance[3] |
| Cells run flat quickly | The switch left at SAVE, which keeps the LCD chips powered | Switch to OFF when not saving a game. Alkaline cells give about 22 hours of play[2][4] |
| Faint or patchy display | Weak cells first; then the LCD or its connection | Fit fresh cells. The display is a custom LCD driven by two HLCD0569 chips; no repair procedure has been published[2] |
| One key never responds | Key contact | Test the key where it must act; clean the contacts from inside |
| Board appears but the game does not respond to any key | Processor not running | Check the cells under load. The INS8050 runs from a 6 MHz crystal; with the case open, an oscilloscope on the crystal shows whether the processor's clock is running[2] |
Final notes
[edit | edit source]- The program is in the INS8050's own ROM, so the processor cannot be replaced by a blank part.[2]
- The Soviet Elektronika IM-29 is a close copy of the Mattel game, made in 1992, but its board is laid out differently, running into the space the Mattel uses for batteries.[5]
- Capacitors are covered, as far as anything is known, on Mattel Computer Chess Capacitor Replacement Guide.
Related pages
[edit | edit source]- Mattel Computer Chess
- Mattel Computer Chess General Maintenance
- Mattel Computer Chess Capacitor Replacement Guide
- Capacitor Failure Symptoms
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Mattel Electronics, Computer Chess instruction booklet, pp. 2-3, "The Controls", as reproduced by Spacious Mind and hosted as File:Mattel Computer Chess controls drawing (Mattel instructions).png: the LCD chessboard; OFF / ON / SAVE; the game keys; LEVEL 1 to 4; direction keys; MOVE; ENTER MOVE; COLOR "allows black to move first"; CLEAR "clears the board (at start of game), or erases the cursor (during the game)".
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 MAME source, src/mame/mattel/chess.cpp (retrieved 2026-10-19): no sound hardware; SAVE keeps the LCD chips powered and the position is read back from LCD RAM; press CLEAR before powering off to save a game; the level setting is not saved; no new-game button, switch off and on; INS8050 at 6 MHz with 4 KB internal ROM; two HLCD0569 LCD drivers; custom LCD.
- ↑ Handheld Games Museum, "Mattel Computer Chess" (retrieved 2026-10-19): 4 AA batteries.
- ↑ Spacious Mind, "Mattel Computer Chess Model 1992-0320" (retrieved 2026-10-19): "4 AA alkaline batteries = approximately 22 hours of use", from the user manual and box.
- ↑ Chess Computer UK, "Elektronika Chess Partner IM-29" (retrieved 2026-10-19): made in 1992; a very close copy of the Mattel; its PCB intrudes into the "Mattel" battery compartment space.