Grandstand Crazy Monster Troubleshooting Guide
The Grandstand Crazy Monster is Grandstand's 1983 release of Epoch's Zig-Zag Monster.[1][2] There is no service manual, and only one repair of this hardware has been published: a Korean collector's 2026 repair of an Epoch Zig-Zag Monster with a dim display and faulty controls.[3] Most of what follows is therefore Grandstand's own leaflet and that one repair. Case opening and cleaning are on Grandstand Crazy Monster General Maintenance.
What should happen at power-on
[edit | edit source]- With the Power and Sound switches both on, the game makes an electronic sound and the display lights.[1]
- The skill level is set to Level 1 and "1" appears at the top of the display. Skill Level Select steps through the three levels.[1]
- Start gives a short signal and begins play. At the end of a game, Start begins the next one; there is no need to switch off.[1]
- With the Sound switch off the game plays silently.[1]
Measurements
[edit | edit source]No voltages have been published for this board. The only figure that can be given is the supply: four C cells, nominally 6 V, or a Grandstand Universal Mains Adaptor on negative polarity.[1] Measure the cells under load if the display is dim; weak cells are the leaflet's first suspect for an erratic game.[1]
Symptom checklist
[edit | edit source]| Symptom | Likely cause | Action | Source |
|---|---|---|---|
| Game malfunctions or display is erratic | Weak cells | Fit four fresh C cells | [1] |
| Game runs but the display is dim | Aged electrolytic capacitors in the display supply | Replace the five electrolytics; see Grandstand Crazy Monster Capacitor Replacement Guide | [3] |
| Joystick directions or buttons do not respond | Dirty or worn rubber pads, dirty control-board contacts | Dismantle the control panel and clean the pads and the board | [3] |
| No power on cells | Corroded battery contacts | Remove and clean the contacts | [3] |
| No sound, game otherwise normal | Sound switch off, or the switch's contacts dirty | Check the switch; clean it | [1][3] |
| Works on cells, not on an adaptor, or the other way round | DC socket or its leads; adaptor polarity | Check the socket and leads; use 6 V centre negative | [1][3] |
Known faults on this game
[edit | edit source]Dim display
[edit | edit source]The Zig-Zag Monster in the Korean repair switched on and ran, but its display was dim. The repairer cleaned the board and the tube, tested it, found the display still dim, and replaced all five electrolytic capacitors on the main board; at the next power test the display was bright.[3] This is the only fault on this hardware for which a cause has been published. The values and positions are on Grandstand Crazy Monster Capacitor Replacement Guide.
A tube can also fade on its own. The Handheld Museum's administrator, writing about another Epoch VFD game, says these tubes fade with years of heavy use, unevenly, the most-lit parts first, and that a broken filament wire leaves one area very dim; neither can be repaired.[4] An even dimming that returns to full brightness with new capacitors, as in the Korean repair, is the supply.
Controls
[edit | edit source]The same game's controls were faulty; the repairer dismantled the control pad, serviced it, and reassembled it before the final test.[3] The joystick and buttons work through rubber pads pressing on the green control board, so dirt on the pads or the board is the first thing to clean.[3] Grandstand's leaflet asks players not to press hard on the Action buttons and to move the joystick gently, to avoid damage.[1]
Display faults
[edit | edit source]The display is a vacuum fluorescent tube mounted on the main board, viewed through an oval magnifying lens and a printed film.[3] Its part number has not been published; a marking ending "8BM24T" is printed on the board beside it.[3] The tube's segments are this game's own shapes (Mr. Fred, the tree, the monsters, the doors and the tank), so a replacement can only come from another copy of the game.[1]
| Symptom | Likely cause | Action | Source |
|---|---|---|---|
| Dim all over | Weak cells; aged capacitors in the display supply | Fresh cells; then replace the five electrolytics | [1][3] |
| Erratic display | Weak cells | Fresh cells | [1] |
| No display, no sound | No power: cells, contacts, socket, Power switch | Work back from the battery contacts with a meter | [3] |
| One area very dim, or the most-used figures faded | Broken filament wire; worn phosphor | Not repairable | [4] |
| Tube cracked or tip broken | Vacuum lost | Not repairable; a tube from another Crazy Monster or Zig-Zag Monster is the only replacement | [1] |
Keep fingers off the transformer while the board is powered with the case open: on Astro Wars, whose supply is built the same way, the winding was measured at about 200 V peak to peak.[5]
Things that are not faults
[edit | edit source]- No sound with the Sound switch off.[1]
- The level always returns to 1 when the game is switched on.[1]
- The game ends with chances left if the water tank empties while there is no fruit on the tree.[1]
- A score of 2,000 ends the game: that is a perfect score.[1]
- The Action buttons do not respond faster to harder presses.[1]
What can be repaired
[edit | edit source]| Part | Repairable? | Notes |
|---|---|---|
| Electrolytic capacitors | Yes | Five on the main board[3] |
| Battery contacts, DC socket, slide switches | Yes | Clean or replace |
| Rubber contact pads and control board | Yes | Clean[3] |
| Display tube | Only from another copy of the game | Game-specific shapes[1] |
| Microcontroller | Not identified | No replacement source is known |
Related pages
[edit | edit source]- Grandstand Crazy Monster
- Grandstand Crazy Monster General Maintenance
- Grandstand Crazy Monster Capacitor Replacement Guide
- Grandstand Universal Mains Adaptor
- Capacitor Failure Symptoms
References
[edit | edit source]- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 Adam Imports Ltd, Grandstand Crazy Monster: Electronic Mini Arcade Game directions, copyright 1983, made in Japan. Hosted here as File:Grandstand Crazy Monster Instructions.pdf (read from 200 and 300 dpi renders): p. 1, the labelled drawing of the game (Sound and Power switches, Skill Level Select and Start buttons, joystick, two Action buttons) and the Batteries box ("GRANDSTAND recommend the use of 4 DURACELL MN 1400 batteries"; "can be operated from the mains with a GRANDSTAND Universal Mains Adaptor (not included). Set polarity switch to negative-polarity"; the game "will not operate properly if batteries are weak", and if it "malfunctions or display is erratic check or replace batteries"; switch off after use and remove the batteries for long periods), and the note "This is a precision electronic instrument and it should not be abused. Please move the Joy Stick gently. Do not press hard on the Action Button. It will not operate any faster and will avoid damage. Do not leave in the sun or allow it to get wet."; p. 2, with both switches on "you will hear an electronic sound and the game display will light up"; at switch-on the skill level is set to Level 1 and "1" is shown at the top of the display; three levels (7, 5 or 3 chances; one, two or three monsters; slow, medium or fast); Start gives "an electronic signal" and starts a new game at the end of one; the joystick moves Mr. Fred right, left, up or down; the "Game Display" drawing; p. 5, the game ends when the tank is empty with no fruit on the tree, when the last chance is lost, or at a perfect score of 2,000; p. 6, Adam Imports Limited, Harrogate, copyright 1983, made in Japan.
- ↑ Handheld Museum, "Grandstand Crazy Monster" and "Epoch Zig-Zag Monster" (retrieved 2026-10-18). Grandstand Crazy Monster: VFD, four C batteries, "Also sold by Epoch (and possibly Gakken) as Zig-Zag Monster"; Epoch Zig-Zag Monster: 1983, VFD, four C batteries, model 36270, "Also sold by Grandstand as Crazy Monster". The photographs, examined, show both games in the same yellow upright case with an oval screen, the same control layout and the same screen artwork, one with Grandstand's name strip and leaflet, the other with Epoch's.
- ↑ 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 3.13 3.14 analo9, "1983 에포크 지그재그 몬스터 게임기 (Epoch ZigZag Monster)", 아날로그 탐구생활 (Naver blog, in Korean), 25 June 2026 (retrieved 2026-10-18); the same repair on YouTube as "1983 에포크 지그재그 몬스터 게임기 (Epoch ZigZag Monster FL LSI Tabletop Game repair)". An Epoch Zig-Zag Monster that powered up with a dim display and faulty controls. The step captions: dismantling; main board removed; battery contacts removed and serviced; control pad dismantled and serviced; board circuit and parts checked; board cleaned; VFD cleaned; power test, "VFD brightness poor"; parts replaced; power test, "VFD brightness good"; reassembly; game test. Its 60 photographs (1,280 × 717 pixels), examined at full size, show the case opened into the screen frame (an oval magnifying lens on a black plate held by four screws, and the printed screen film) and the body; the main board under a black mask plate with a window for the tube; the control-panel moulding (joystick, two Action buttons, SOUND and POWER slide switches, SELECT and START buttons) with the speaker in a foam-padded ring at its top; underneath it, rubber contact pads and two metal slide switches over a green control board marked 96272; a flat cable between the boards; the DC socket on red and black leads; a battery compartment with coil springs in the sloping back of the case; the main board, brown, with the Epoch logo and a sticker 11630518, its solder side marked 96271, the tube mounted on it with its sealed glass tip at one end, a marking ending "8BM24T" on the board beside the tube, a TDK transformer marked TX-29 and "33", a power transistor at S02, diodes S07 to S10, ceramic capacitors including C06 and C08 to C10, and five electrolytic capacitors, C01 (the largest, beside the flat cable), C02, C03, C04 and one whose label is hidden; and the five old electrolytics after removal, marked 100 µF 16 V, 10 µF 50 V and 0.47 µF 50 V, the other two not legible (one of them reads only "85°C"), with the new parts fitted: C01 100 µF 50 V, C02 and C03 22 µF 50 V, and two smaller parts whose values are not legible in the photograph.
- ↑ 4.0 4.1 Handheld Museum forum, "EPOCH Astro Command - dead or dying", January 2016 (retrieved 2026-10-18). The site administrator (Rik): "I've never had a VFD just die, unless the glass was physically broken"; with heavy use they fade, "usually not even evenly", the parts lit most fading fastest, over years; a broken filament wire makes an area of the display very dim.
- ↑ Handheld Museum forum, "Astro wars / galaxy ii repair", pages 1 and 2, December 2018 to January 2019 (retrieved 2026-10-18): on Epoch's Galaxy II hardware (Grandstand Astro Wars), whose display supply is built round a D882 power transistor switching 6 V into a transformer, an owner measured about 200 V peak to peak on the transformer winding with a basic oscilloscope he said was probably not accurate at that level.