Grandstand Scramble Capacitor Replacement Guide
The electrolytic capacitors on the main board of the Grandstand Scramble, Epoch's Astro Command sold under Grandstand's name.[1] No parts list or schematic has been published for Scramble or Astro Command. The positions and values below were read from frames of four repair videos that show the board close up, three of Grandstand Scrambles and one of a 1987 Radio Shack Astro Command, each looked at at full size (1080p). On the Grandstand boards two values are established: C01 is 330 µF 10 V and C07 is 10 µF 16 V. The other two electrolytics lie with their markings against the board, and no source shows them. Faults that are not capacitors are on Grandstand Scramble Troubleshooting Guide; general signs of a failing capacitor are on Capacitor Failure Symptoms.
What the capacitors do on this board
[edit | edit source]Scramble runs from four C cells (6 V) or a 6 V adaptor. The supply comes in through the DC socket and the power switch on the control board and reaches the main board through the flat cable.[2][3] On the main board a D882 power transistor drives a small round TDK transformer (marked TY-81 on the boards in Kip Hakes's and Rust Belt's videos), and diodes rectify its output into the voltages the microcontroller and the display need.[4][3] The NEC μPD553C microcontroller runs from about −10 V and drives the display directly at up to −35 V.[5]
With no schematic, nobody has traced which rail each capacitor smooths. The ratings narrow it down. A 10 V part such as C01 cannot sit on the display supply, which on this NEC chip reaches −35 V, so it belongs on the low-voltage side;[5] on Astro Wars, the Epoch game nearest in design, a 330 µF 10 V capacitor is on the +6 V line.[6] On the Radio Shack board the 47 µF capacitor is rated 50 V, enough for the display side, while the 220 µF part is rated 16 V.[4]
Capacitor list
[edit | edit source]Grandstand boards
[edit | edit source]Positions are given with the component side facing you, the display along the bottom and the transformer at the right, as in Kip Hakes's video. The Grandstand boards in the three videos are not all laid out alike (retro_restos's board has the C11 disc at the left-hand end, Kip Hakes's has it at the top right), so check each designator against the silkscreen on your own board.[3][7]
| Ref | Where it is | Value | Voltage | Evidence | Notes |
|---|---|---|---|---|---|
| C01 | Bottom right corner, at the right-hand end of the display, beside the ceramic disc C10 and diode S07 | 330 µF | 10 V | NTK part marked 330 µF 10 V beside the silkscreen C01, read aloud and shown close up by Retro Tech Repair[8] | Burst on Retro Tech Repair's game and sprayed its contents onto the case; replaced with 330 µF 25 V. Lying down on his board, standing on Kip Hakes's[8][3] |
| C05 | Lying flat above the microcontroller | Not legible | Not legible | Silkscreen C05 beside a grey NTK part on retro_restos's board; marking faces the board[7] | Kip Hakes's board has two grey NTK parts lying in the same area, markings also hidden[3] |
| C06 | Lying flat beside C05 | Not legible | Not legible | Silkscreen C06 beside a grey NTK part on retro_restos's board[7] | See the Radio Shack table below for the values in this area on that board |
| C07 | Left-hand end, beside the resonator X02 and diode S10 | 10 µF | 16 V | NTK part marked 10 µF 16 V beside the silkscreen C07 on Kip Hakes's board; retro_restos's board has an NTK 10 µF 16 V part lying at the same end, beside the disc C11[3][7] |
The other C-numbered parts on Kip Hakes's board (C02, C03 and C04 beside the transistors at the top right, C08 and C09 beside the resonator, and the larger discs C10 and C11) are ceramic capacitors, not electrolytics.[3]
Radio Shack Astro Command (1987)
[edit | edit source]Rust Belt Vintage Toy Repair replaced three electrolytics on a 1987 Radio Shack Astro Command and circled them on screen. Its board is laid out differently from the Grandstand boards (small transistors sit at the top left, where Kip Hakes's board has the resonator and C07), so these are that board's values, not a list for Scramble.[4]
| Where it is | Value | Voltage | Evidence |
|---|---|---|---|
| Lying above the microcontroller, left of the pair | 47 µF | 50 V | Marking on the part[4] |
| Lying above the microcontroller, right of the pair, beside diodes S04 and S05 | 220 µF | 16 V | Marking on the part (Nitsuko)[4] |
| Standing at the bottom right corner, beside the disc C10 | Not legible | Not legible | A blue part; only "8616" faces the camera[4] |
Failure signs on Scramble
[edit | edit source]- Retro Tech Repair opened a dead Scramble and found C01 swollen and split, with its electrolyte sprayed onto the inside of the case below the corner of the board. He replaced it and the D882 power transistor together, so his video does not show which of the two had stopped the game.[8]
- A dead Scramble is usually down to the D882, not a capacitor. Kip Hakes, retro_restos and Buy it Fix it each brought a dead Scramble back with a new power transistor alone; Kip Hakes looked over the capacitors first and found none bulging.[3][7][9] The owner of a dead Epoch Astro Command replaced all the electrolytics without curing it.[2]
- Rust Belt replaced all three electrolytics on his Radio Shack board while he had it apart, after fixing the D882, on the grounds that after 37 years their electrolyte dries up.[4]
No published Scramble repair traces a dim display or missing sound to a capacitor. For a game that plays and makes its sounds with a dark display, see Display faults.
Reading and recording your own board
[edit | edit source]Because the boards differ between production runs and two of the four electrolytics have never been read, record your own board before ordering parts.
- Photograph the component side before touching anything, square on and with enough light to read the silkscreen. Note the number on the white label sticker and the date code on the D553C 202; the videos show several different stickers and codes.[3][7][8]
- For each electrolytic, write down its C number, its value and voltage, the maker's mark (NTK on the Grandstand boards), whether it stands or lies flat, and which way its negative stripe faces. The silkscreen marks the positive pad with "+".[3][7]
- C05 and C06 lie with their markings towards the board. Read them once they are out, before the new parts go in.[7]
- Compare what you find with the tables above, and note any difference in layout.
Replacement procedure
[edit | edit source]- Take out the cells. Peel back the sticker or cap on top of the joystick knob (on some games it is glued; acetone or alcohol softens it), undo the small screw beneath and lift the knob off.[4][10]
- Remove the six screws in the base and lift the top cover away. Unclip the bezel; two screws hold the main board's bracket.[4] Full details are on Grandstand Scramble General Maintenance.
- Keep the piezo speaker's two thin wires slack, and free the battery leads if they are in the way, noting which wire goes where.[4] Cover the display while you work; it is a glass tube.[7]
- Note the polarity of each capacitor, then remove it.
- Fit new radial electrolytics of the same capacitance and the same or a higher voltage, with the stripe the same way round. Retro Tech Repair fitted a 330 µF 25 V part at C01 and laid it down as the original had been.[8][4] Rust Belt checked each new capacitor on a component tester before fitting it.[4]
- Refit the bracket, bezel, top cover and knob. The screws go into soft plastic posts: turn each one backwards until it drops into its thread before tightening.[8]
After the work
[edit | edit source]| Check | Expected | Source |
|---|---|---|
| Supply at the board | 5.8-6.2 V from fresh cells or a 6 V supply | [7][9] |
| At switch-on | The game starts; SELECT chooses one of four skill levels | [4][11] |
| Display | Cyan and red segments behind the colour overlay | [1] |
| Controls | The ship moves four ways; MISSILE fires ahead, BOMB drops | [4] |
No owner has published Scramble's internal supply voltages, so there is no reference figure for the −10 V and display rails on this game. If the game is still dead, test the D882 next: see D882 power transistor.
Related pages
[edit | edit source]- Grandstand Scramble
- Grandstand Scramble General Maintenance
- Grandstand Scramble Troubleshooting Guide
- Grandstand Astro Wars Capacitor Replacement Guide: the Epoch game nearest in design, with a published parts list
- Capacitor Failure Symptoms
- Battery Explosion, Capacitor or Corrosion Damage
References
[edit | edit source]- ↑ 1.0 1.1 MAME source, hh_ucom4.cpp at commit d404316 (retrieved 2026-10-18). Driver notes for Epoch Astro Command: PCB labels 96111 and 96112; NEC μPD553C microcontroller labelled D553C 202, 1-bit sound; cyan and red VFD NEC FIP9AM20T no. 42-42 (nine grids); colour overlay with the right three columns yellow and six columns of the bottom row pink; released in Japan by Epoch, in the USA by Tandy and in the UK by Grandstand as Scramble.
- ↑ 2.0 2.1 Handheld Museum forum, "EPOCH Astro Command - dead or dying", January 2016 (retrieved 2026-10-18). The owner of a dead Epoch Astro Command (the Epoch version of Grandstand Scramble) found that its supply runs from the control board to the main board through a flat cable; he replaced the electrolytic capacitors and later swapped almost every part with a working Radio Shack Astro Command, and the game stayed dead.
- ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 Kip Hakes, "Grandstand Scramble - Boxed, Beautiful, Broken - Fix it Friday", YouTube, 1 March 2024 (transcript read 2026-10-18; board frames at about 9:00-9:20 looked at at full size, 2026-10-19). A boxed Grandstand Scramble, dead on batteries; about 6 V reached the power switch (5:58-7:31). "The capacitors look okay, we don't have any bulging" (8:51-9:06); the NEC D882 tested dead and a new one cured the game (10:32-14:38). The board in the frames: NEC D553C 202 with date code 8226ED, a round TDK transformer marked TY-81 at I01, the resonator X02 with diode S10 at the left-hand end, and four electrolytics, all grey NTK parts: an upright 10 μF 16 V beside the silkscreen C07 at the left-hand end; two lying flat above the microcontroller, markings hidden; one standing at the bottom right corner beside the disc C10, marking turned away. Ceramic capacitors C02, C03, C04, C08, C09, C10 and C11; "+" marks beside the electrolytic pads.
- ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 Rust Belt Vintage Toy Repair, "1987 Radio Shack Astro Command Electronic Game Repair", YouTube, 31 October 2024 (transcript read 2026-10-18; frames from 4:22 to 4:52 looked at at full size, 2026-10-19). Remove the batteries; peel the sticker off the joystick knob and remove the screw beneath; six screws separate the base from the top cover; the bezel unclips; two screws hold the main board's bracket (2:45-3:07). The D882 power transistor converts the incoming DC to pulses that drive the transformer, and rectifier diodes turn the transformer's output back into DC at the levels the processor and display need; the D882 had failed and a new one cured the game (3:24-4:16). "It is also a good idea to replace these three electrolytic capacitors", because after 37 years the electrolyte dries up; same capacitance, same or higher working voltage, observe polarity; each replacement tested on a component tester before fitting (4:22-4:52). The frames show the three circled on a board labelled 11360801 with an NEC D553C 202 (date code 8616P7) and a TDK TY-81 transformer: two lying above the microcontroller, marked 47 μF 50 V and Nitsuko 220 μF 16 V, and a blue part standing at the bottom right corner beside the disc C10, of which only "8616" can be read. Do not strain the thin piezo speaker wires; the battery contacts are wired and were removed for polishing (4:54-5:12).
- ↑ 5.0 5.1 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, 42-pin DIP, single −10 V supply; outputs that can be pulled to −35 V to drive a VFD directly.
- ↑ My Mate VINCE, "1981 Grandstand ASTRO WARS Tabletop Game - No Power Fault - Trying to Fix", YouTube, 10 January 2021 (transcript read 2026-10-18). On a Grandstand Astro Wars, a previous owner had found a 330 μF 10 V capacitor blown on the +6 V line (0:00-3:00).
- ↑ 7.00 7.01 7.02 7.03 7.04 7.05 7.06 7.07 7.08 7.09 retro_restos, "Grandstand Scramble Repair. No Power Fix", YouTube, 19 May 2023 (transcript read 2026-10-18; board frame at about 8:00 looked at at full size, 2026-10-19). Dead on mains and batteries; 5.8 V reached the board (3:58-4:18); the D882 power transistor had failed and a new one cured it (6:20-12:00); he covered the display while working (7:00). The board in the frame: NEC D553C 202 with date code 8222E7; two grey NTK electrolytics lying above the microcontroller beside the silkscreen C05 and C06, markings towards the board; an NTK electrolytic marked 10 μF 16 V lying at the far end of the board beside the ceramic disc C11 and links J01 and J03; a fourth, upright, at the other end of the display.
- ↑ 8.0 8.1 8.2 8.3 8.4 8.5 Retro Tech Repair, "Grandstand Scramble / Astro Command Repair - Retro Games", YouTube, 7 December 2018 (transcript read 2026-10-18; frames at 6:40 and 8:48 looked at at full size, 2026-10-19). A dead Grandstand Scramble (board label 11020921). An electrolytic capacitor at the corner of the board beside the end of the display had burst and expelled its contents onto the plastic case below it (6:30-6:50). He read it as a 330 μF 10 V part; the close-up shows an NTK capacitor marked 330 μF 10 V beside the silkscreen C01 (8:38-8:48). He replaced it with a 330 μF 25 V part, explaining that the voltage rating is a maximum, and laid it down because the original was laid down (8:51-9:21, 11:17-11:27); the D882 power transistor, which read short base to collector, was replaced at the same time, and the game then worked from a 6 V bench supply (9:33-14:43). Tip for the plastic screw posts: turn each screw backwards until it drops into its thread before tightening (5:46-5:53).
- ↑ 9.0 9.1 Buy it Fix it, "Repairing A Vintage Grandstand Scramble", YouTube, 20 May 2022 (transcript read 2026-10-18). A dead Scramble: about 6.2 V at the board, dropping slightly when switched on (2:39-4:40); the large power transistor measured a dead short out of circuit; a new transistor cured it (7:35-14:04).
- ↑ retro_restos, "From Delivery to Repair in 10 Minutes. Grandstand Scramble 'No Power' Fix", YouTube, 8 February 2024 (transcript read 2026-10-18). The cap over the joystick screw is glued; soak it off with acetone or alcohol and glue it back (4:45, 11:33-11:39). Six screws in the base, then lift the top away (5:25-6:06).
- ↑ Vintage Gaming Memories, "Joystick Repair & Full Cleaning: 1982 Epoch Astro Command", YouTube, 4 March 2025 (transcript read 2026-10-18). Five phases and four skill levels (12:24).