Grandstand Caveman Troubleshooting Guide
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Fault-finding on the Grandstand Caveman, Grandstand's UK release of Tomy's Caveman (also sold by Tandy).[1][2] No service manual or schematic has been published. The faults below come from four repairs, three of them on Tomy units by the Korean repairer analo9 and one on a Grandstand unit by Buy it Fix it, plus Tomy's UK instruction book and the MAME driver notes. Dismantling and cleaning are on Grandstand Caveman General Maintenance.
What a working game does
[edit | edit source]- Set AMA or PRO first, then switch on. The display shows the dinosaur, its children, the dragon, the eggs and the volcanic bombs.[3]
- Press START/SHOOT: a fanfare plays and the number of cavemen, four to begin with, appears.[3]
- The MOVE lever moves the caveman left and right; SHOOT throws the stone axe.[3][1]
Measurements
[edit | edit source]| Point | Value | Source |
|---|---|---|
| Battery supply | Four 1.5 V C cells, 6 V | Tomy leaflet[3] |
| Adaptor (Tomy) | 7.5 V DC, 200 mA, 2.1 mm plug, centre negative | Tomy leaflet[3] |
| Microcontroller | NEC μPD553 (D553C 209): PMOS, single −10 V supply; display outputs rated to −35 V | NEC data sheet, MAME[4][1] |
| Clock | 400 kHz, from the ceramic resonator marked CSB on the board | MAME, photographs[1][5] |
No voltages at named test points on the Caveman board have been found.
Symptom table
[edit | edit source]| Symptom | Likely cause | Action | Source |
|---|---|---|---|
| Does not start properly at switch-on | A known quirk of the game's power-up | Switch off and on again, as Tomy's book advises, before treating it as a fault | [3] |
| Dead on fresh cells | Corroded battery contacts or leads | Clean the contacts and leads; measure the cell voltage at the board | [5][6] |
| Dead on cells and adaptor | Battery contacts; the W06A diode on the control board; parts of the display supply around the D471 power transistor | See below | [7][5] |
| Display dark, play goes wrong | Weak cells | Fit fresh alkaline C cells | [3] |
| Lever, button or a switch unreliable | Dirty control-board pads, rubber contacts or slide-switch tracks | Clean with isopropyl alcohol | [6][8] |
| AMA/PRO setting ignored | Changed during a game | Switch off, set the selector, switch on | [3] |
| Died after a different adaptor was used | Reversed polarity or excess voltage | Check the D471 and C945 transistors and the W06A diode | [9][7] |
| Sound but a dark display | The display supply or a broken tube | See below | [10] |
| Faded colours | Phosphor wear | Not repairable | [1] |
Dead and silent
[edit | edit source]
- Read the leaflet's note first: the game "may fail to function properly depending on how the game-machine is switched on". Switch off and on again.[3]
- Fit fresh cells and measure 6 V at the battery terminals. The Grandstand Caveman repaired by Buy it Fix it was dead until its battery terminals were cleaned; analo9's 2026 repair also found a battery contact fault.[6][5]
- Try a measured 7.5 V centre-negative adaptor in the side socket. If the game runs on one supply and not the other, look at the contacts of the dead supply and at the W06A diode on the green control board, between the pads marked BAT and AC. analo9 replaced this diode on a Tomy Caveman that would not switch on.[7]
- Follow the supply through the ON/OFF slide switch, whose tracks are on the control board; clean them.[6]
- On the main board, check the TO-126 power transistor marked D471 and the C945 beside it, out of circuit. On the same no-power Caveman analo9 replaced the C945 and a small ceramic capacitor next to it.[7] The 2026 repair replaced all five electrolytics; see Grandstand Caveman Capacitor Replacement Guide.[5]
- If the supply reaches the D553C 209 and the game still does nothing, the microcontroller or its 400 kHz resonator may have failed. The program is mask-programmed into the chip, so a replacement must come from another Caveman: Tomy's, Tandy's or Grandstand's.[1]
Sound but no display
[edit | edit source]A Caveman that plays its fanfare when START/SHOOT is pressed, with nothing on the screen, has a working microcontroller; suspect the display's own supply or the FIP8AM20T itself. The display supply on the TN-12 board is built around the green transformer, the D471 power transistor, the C945, the 1SS53 and W06C diodes and the RD12EB3 zener.[5][7] No Caveman report of this fault has been found.
Broken glass is the usual way these tubes die, according to the Handheld Museum's administrator.[10] Lift off the smoked housing and look over the upright tube and the sealed tip at its end before replacing parts.
Things that are not faults
[edit | edit source]- The game may not start properly at switch-on; Tomy's book says to switch off and try again.[3]
- The AMA/PRO selector has no effect once a game has started.[3]
- The score display reads up to 1,990 and then returns to 0; each 2,000 points lights an egg in the cave instead.[3]
- An egg left for eight seconds hatches and the dinosaur's children laugh at the caveman; that is part of the game.[3]
What is repairable
[edit | edit source]- Repairable: battery corrosion, the control contacts and switches, the W06A diode, the transistors and capacitors of the supply.[5][7][6]
- Replaceable only from a donor Caveman: the D553C 209 microcontroller and the FIP8AM20T display.[1]
- Not repairable: a cracked display tube, faded phosphor.[10][1]
Related pages
[edit | edit source]- Grandstand Caveman
- Grandstand Caveman General Maintenance
- Grandstand Caveman Capacitor Replacement Guide
- Grandstand Munchman Troubleshooting Guide
- Grandstand Tron Troubleshooting Guide
- Grandstand Universal Mains Adaptor
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 MAME source, hh_ucom4.cpp (retrieved 2026-10-18). Driver notes for Tomy Caveman: made in Japan; PCB label TN-12 2E114E03; NEC uCOM-43 microcontroller labelled D553C 209, 1-bit sound; cyan/red/green VFD NEC FIP8AM20T no. 2-42; releases Caveman (Tomy, world), Caveman (Tandy, USA) and "Cave Man - Jr. Caveman vs Dinosaur, published by Grandstand" (UK); inputs left, right, one button and the AMA/PRO switch; the machine configuration clocks the D553 at 400 kHz. The chip list dates the D553C 209 to 1982. File header: NEC FIP part numbers give the number of grids; "after decades passed, all the colors fade".
- ↑ Handheld Museum, "Grandstand Caveman" and "Tomy Caveman" (retrieved 2026-10-18): 1982, VFD, four C batteries; Tomy model 7613; made by Tomy and licensed to Grandstand for UK distribution; found in gold and in white and orange cases; also sold by Radio Shack under the Tandy name.
- ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 Tomy, Caveman instruction book, UK edition (marked GB), hosted here as File:Tomy Caveman Instructions.pdf. Page 1: controls drawing (MOVE lever, SHOOT button that also starts the game, power switch, game selector AMA/PRO); "Open the cover of the battery compartment at the rear of the game-machine. Insert four 1.5 V baby cells as shown in the diagram"; "The computer may fail to function properly depending on how the game-machine is switched on. If it does not work, turn the Power Switch off"; AC adaptor 7.5 V DC 200 mA, 2.1 mm ID coaxial plug, tip (centre) negative; "When not in use, disconnect the adaptor. Do not use any other adaptor than the type recommended". Page 3: set the selector before switching on; it cannot be changed once the game has started. Page 4: scoring; the score display reads to 1,990 points and then returns to 0, with an egg in the cave lit for each 2,000; care: no extremes of temperature, avoid wet or dirt, "Don't take it apart", don't shake or drop, switch off when not in use, don't leave used batteries in; "If the batteries become weak the display screen will become dark and show incorrect action"; drawing of the adaptor plug entering the socket in the side of the case.
- ↑ NEC Electronics USA, 1982 Microcomputer Catalog, data sheet "μPD552/μPD553 4-bit single chip microcomputers with vacuum fluorescent display drive capability", p. 165, Bitsavers copy on the Internet Archive: PMOS chips in a 42-pin DIP running from a single −10 V supply; 27 output lines "are capable of being pulled to −35V in order to drive Vacuum Fluorescent Displays directly".
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 analo9 (아날로그 탐구생활), "1981년 추억의 게임기 『토미 케이브맨』(TOMY CAVEMAN)", Naver blog, 3 September 2026 (in Korean; retrieved 2026-10-18), with the matching YouTube video OOn3iG6zNIk. A gold Tomy Caveman that would not switch on: diagnosed as a battery contact fault; the game was dismantled, the board removed and checked and parts replaced; the display and the key contacts were cleaned; the battery contacts restored. 47 photographs (1280 px), looked at at full size: the DC socket in the right-hand side of the base; the battery cover under the rear of the base; four C cells in two rows; the top shell (hood and front in one piece) lifted off with the printed window plate and the black control faceplate clipped inside it; the display standing upright in black rubber end blocks inside a smoked plastic housing; the main board TN-12 2E114E03 lying flat in the base with the green control board 2E114E02 beside it under a black switch carrier with yellow sliders; the five electrolytics removed from the main board, marked 3.3 µF 50 V, 10 µF 50 V, 33 µF 25 V and 47 µF 50 V (the fifth's marking faces away); the main board silkscreen "3.3U 50V" beside the C945, "10UF 50V" and "47UF 50V" beside the RD12EB3 zener, a blue resonator marked CSB, SL121J and SL471J 50 V and Z223Z 50 V capacitors, 1SS53 and W06C diodes, D471 and C945 transistors, resistor networks RGSD12X154M and RGSD14X154M.
- ↑ 6.0 6.1 6.2 6.3 6.4 Buy it Fix it, "Repairing A Vintage Tomy / Grandstand Caveman Game", YouTube, 8 September 2022, 17:03 (watched 2026-10-18; no transcript available). A Grandstand-branded Caveman sold on eBay as "Been in attic for last 20 years. Unable to get working"; dead on fresh C cells. Shown: the screws in the base removed and the top shell lifted off (1:30-2:00); the control faceplate and switch carrier removed (2:15); the control board's contact pads and the rubber contacts cleaned with isopropyl alcohol on swabs (3:00-5:00); the slide-switch carrier cleaned (7:30-8:45); the battery terminals measured (9:15) and cleaned with swabs and contact cleaner spray (10:00-12:30); the display then lit on the cells (13:15) and the reassembled game played (16:15-16:30).
- ↑ 7.0 7.1 7.2 7.3 7.4 7.5 analo9, "1981 추억의 게임기 『토미(영실업) 케이브맨』(TOMY CAVEMAN)", Naver blog, 21 November 2023 (in Korean; retrieved 2026-10-18), with the video -QnFHPQRNxI. A gold Tomy Caveman (imported to Korea by Young Toys in 1984) that would not switch on, repaired and overhauled: circuit checked, parts replaced, power tested, display cleaned. Photographs: the W06A diode on the control board 2E114E02, between the pads marked BAT and AC, replaced (the old glass diode shown beside the board); a C945 transistor and a small ceramic capacitor removed from beside the TO-126 power transistor marked D471; the back of the tube marked NEC FIP8AM20T.
- ↑ analo9, "1981 토미 LSI 게임기 "케이브맨"(TOMY CAVEMAN)", Naver blog, 2 November 2022 (in Korean; retrieved 2026-10-18). A red Caveman made for export to North America: it powered up but its control buttons misbehaved, and it was dismantled and overhauled.
- ↑ Handheld Museum forum, "Astro wars / galaxy ii repair", December 2018 - February 2019 (retrieved 2026-10-18). The site administrator (Rik), writing about VFD tabletop games in general: the wrong AC adapter "will usually fry" a transistor, "the most frequent damage I've seen to VFD games"; keep rubber buttons, springs and speakers from scrapped games as spares.
- ↑ 10.0 10.1 10.2 Handheld Museum forum, "EPOCH Astro Command - dead or dying", January-February 2016 (retrieved 2026-10-18). The site administrator (Rik), writing about VFD tabletop games in general: displays fade unevenly with heavy use; he has never had a display fail unless the glass was broken.