Jump to content

Grandstand Crazy Monster Capacitor Replacement Guide

From RetroTechCollection
Grandstand Crazy Monster Instructions cover
Grandstand Crazy Monster, from page 1 of its leaflet. The capacitors sit on the main board behind the screen.[1]

The Grandstand Crazy Monster (Epoch's Zig-Zag Monster) has five electrolytic capacitors on its main board, in the strip below the display tube that also carries the TDK transformer and the power transistor.[2] No parts list or schematic has been published. All the values below come from one repair: a Korean collector's 2026 restoration of an Epoch Zig-Zag Monster whose display was dim until all five were replaced. Its photographs show the old parts after removal and the new ones in place.[2] The Handheld Museum's photographs show Grandstand's Crazy Monster and Epoch's Zig-Zag Monster as the same game in the same case;[3] no photograph of the board inside a Grandstand-branded unit has been published, so check each value on your own board before ordering parts.

Signs that the capacitors need attention

[edit | edit source]
  • The display is evenly dim on fresh cells. This was the symptom the five new capacitors cured.[2]
  • A capacitor top is domed, or there is brown residue on the board beside a capacitor.
  • See Capacitor Failure Symptoms for what to look for.

Crazy Monster capacitor list

[edit | edit source]
Electrolytic capacitors on the main board (read from photographs of Epoch's Zig-Zag Monster)
Position Original part Fitted by the repairer Where Notes
C01 100 µF 16 V 100 µF 50 V Largest capacitor on the board, beside the flat cable Original value legible on the removed part, which matches C01's size; replacement legible in place
C02 Not legible 22 µF 50 V In the row beside the power transistor S02 The removed parts' markings that can be read do not include this value
C03 Not legible 22 µF 50 V Next to C02 As C02
C04 10 µF 50 V or 0.47 µF 50 V Not legible Between C03 and the transformer, just below the tube Both values were legible on removed parts; which went where is not shown
Fifth electrolytic (label hidden) 10 µF 50 V or 0.47 µF 50 V Not legible Next to C04 As C04

Values were read from the repair's photographs at full size (1,280 × 717 pixels): the removed capacitors laid out in front of the board, and the board with the new parts fitted.[2] The originals were grey parts; one of the two unreadable ones shows only "85°C" and a code.[2]

Before ordering, read the values on your own board. Where a value here is "not legible", the part on the board will tell you; keep the same capacitance and use a voltage rating at least as high as the original. The repairer's 50 V parts are a safe choice for the small values.

Replacement procedure

[edit | edit source]
  1. Take out the cells. Open the case and lift the mask plate off the main board, as described on Grandstand Crazy Monster General Maintenance.
  2. Unplug nothing until you have photographed the flat cable, the speaker leads and the DC socket leads.
  3. Free the main board. Protect the display tube: lay the board tube-side up on a soft cloth, and keep the soldering iron and solder sucker away from the glass and its sealed tip at one end.
  4. Note each capacitor's polarity on the board before removing it. The board is marked with + beside the capacitor positions.[2]
  5. Remove one capacitor at a time and fit its replacement before moving to the next, so that values cannot be mixed up between C04 and its neighbour.
  6. Clean flux off with isopropyl alcohol.
  7. Refit the board, mask plate, control panel and screen frame.
[edit | edit source]
  • 105 °C radial electrolytics: 100 µF (C01), 22 µF (two), 10 µF and 0.47 µF, all 50 V if they fit; check C02 and C03 on your own board before ordering, because their original values were not legible.
  • A temperature-controlled soldering iron, desoldering braid or a solder sucker, flux, and isopropyl alcohol.

After the recap

[edit | edit source]

Switch on with fresh cells. The display should be evenly bright, as it was after the repair,[2] and the game should start at Level 1 with "1" at the top of the display.[1] If the display is still dim with new capacitors and fresh cells, look at the power transistor and diodes round the transformer, or at the tube itself; see Grandstand Crazy Monster Troubleshooting Guide.

Warning: keep fingers off the transformer while the board is powered. On Astro Wars, whose display supply is built the same way, the winding was measured at about 200 V peak to peak.[4]

[edit | edit source]

References

[edit | edit source]
  1. ↑ 1.0 1.1 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.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 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.
  3. ↑ 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.
  4. ↑ 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.


Retrieved from "https://wiki.retrotechcollection.com/index.php?title=Grandstand_Crazy_Monster_Capacitor_Replacement_Guide&oldid=26278"