Magnavox Odyssey 500 General Maintenance
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The Magnavox Odyssey 500 (BG7520) dates from 1976 and runs from a 9 V, 200 mA AC adaptor. It has more internal adjustments than the earlier Odyssey consoles, including three for the colour picture, and Magnavox's Service Manual No. 6506 puts limits on which of them should be touched.[1][2] Fault-finding is on Magnavox Odyssey 500 Troubleshooting Guide and the electrolytic capacitors on Magnavox Odyssey 500 Capacitor Replacement Guide.
Before working on the board
[edit | edit source]Magnavox's service adjustments open with three instructions, which apply to any work on the board:[2]
- Check the whole board for shorts and cracks first.
- Monitor the total current drain all the time. The specified drain is 185 mA nominal and 200 mA maximum.[1]
- Drawing excessive current at any time will mean replacing IC1, the regulator and sync chip.
Put a meter in series with the 9 V supply to watch the current. Magnavox's voltage chart was taken with the supply set to give 9 V DC at IC1 pin 2.[3]
Opening the console
[edit | edit source]The service manual has no disassembly instructions.[2]
- Turn the console upside down. Press down on the coin screw in the centre of the cabinet bottom, turn it about half a turn anticlockwise, and lift the cabinet bottom off.[4]
- The channel switch is in the upper right of the board and the sound switch in the upper left.[4][5]
- The cabinet parts list shows the fixings: a cover holding stud, an O-ring retainer and a spring lock nut.[6]
- Refit the cabinet bottom with its grille over the sound switch and the game cord in the cabinet slots.[4]
Power
[edit | edit source]- Use a 9 V adaptor rated for at least 200 mA; Magnavox's own is part 701284-6, supplied with the console. It plugs into the socket above the CENTER and SPEED knobs.[1][7][4]
- The 9 V supply passes the POWER/RESET switch (S1A) and the 68 µH coil L1 to IC1 pin 2, and C1 (470 µF) filters it. IC1 regulates the 5 V supply at pin 3, filtered by C7 (220 µF).[8][7]
| Point | What it is | Expected |
|---|---|---|
| IC1 pin 2 | 9 V input to IC1, after L1 | 9.0 V (the chart condition) |
| IC1 pin 3 | Regulated supply | 4.5 V to 5.5 V (5.25 V on the chart) |
| IC2 pin 1, IC3 pins 2 and 11, IC4 pin 14, IC6 pin 1, IC8 pins 6 and 14 | Other pins at the regulated voltage | 5.25 V on the chart |
| Q3 emitter | Sound oscillator transistor | 9.75 V on the chart |
Switches
[edit | edit source]| Ref | Function | Magnavox part |
|---|---|---|
| S1 | Power on-off and game reset | 160546-5 |
| S2 | Game select (Smash, Tennis, Hockey and Soccer) | 160546-2 |
| S3 | Player select (ball player, tennis player, hockey player) | 160546-2 |
| S4 | Sound defeat, on the board | 160556-1 |
| S5 | Channel select (3 or 4), on the board | 160556-1 |
S1 is a different part from the power switch of the Odyssey 100, 200 and 400 (160546-3); its second section, S1B, resets the score.[7][8] On an Odyssey 100, Nerdly Pleasures cured a noisy picture by cleaning the channel switch and a serve fault by polishing the power switch contacts; the method is on the Odyssey 100 page.[9]
Service adjustments
[edit | edit source]Magnavox's instructions are that the RF filter alignment, the RF oscillator alignment and the RF output level must not be adjusted at any time, and that the video level and 3.58 MHz oscillator adjustments should be made only once they are found to be absolutely essential.[2]
| Adjustment | Control | Connection or setting | Set to |
|---|---|---|---|
| Score indicator position | R102 (score oscillator) | Switch POWER/RESET briefly to OFF and back on to show the W-W win indicators | Letters centred on the screen |
| Upper rebound | R3 | 3 V DC bias on IC3 pin 3; right ball control R40 fully clockwise, left ball control R41 fully anticlockwise | Whole ball visible at the top of the screen |
| Lower rebound | R2 | As above, with R40 fully anticlockwise and R41 fully clockwise | Whole ball visible at the bottom of the screen |
| Blanking width | R43 | Oscilloscope on IC2 pin 5 | 14 µs (+1 µs, −0 µs) |
| Blanking centring | R44 | As above | Horizontal sync 3 µs ± 0.5 µs after the leading edge of blanking |
| Video level | R62 | Only if essential | Good contrast |
| 3.58 MHz oscillator | C41 (trimmer) | Only if essential; game and player switches at Tennis; plastic screwdriver | Light green background, light blue left player, yellow right player |
| Background colour | R54 | Colour receiver only; game and player switches at Tennis | Green background; then check Hockey cyan, Smash magenta, Soccer red |
| Player size balance | R67 | Player switch at Smash; left and right players superimposed | Equal size |
| Right wall position | R13 | Game switch at Hockey | Whole right wall visible at the right edge |
| Goal opening | R25 | Game switch at Hockey | Goal centred vertically |
R54 affects only the background colour.[2] The colours a television shows also depend on its own colour, tint, brightness and contrast settings, so check them before turning C41 or R54.[5][4]
Owner's adjustments
[edit | edit source]The booklet gives the owner only the television's own controls: set the antenna-game switch and channel, switch on with the game at Tennis, and adjust fine tuning, colour and tint until the left "W" is light blue and the right one yellow. If the centre line does not appear, turn the CENTER knob.[4] It has no frequency or wall adjustments for the owner, unlike the booklets for the Odyssey 100, 200 and 400.[4]
Television connection
[edit | edit source]- Push the antenna-game switch fully to GAME or fully to TV.[4]
- Unplug the game cord by its plug, not by the cord.[4]
- A 75 Ω round antenna cable needs a 75 Ω to 300 Ω balun to connect to the switch box.[4]
Preventive maintenance checklist
[edit | edit source]- Check the adaptor's output and rating (9 V, at least 200 mA) before connecting it.[1]
- Measure the current drain on first power-up; it should be about 185 mA and not over 200 mA.[1][2]
- Measure IC1 pin 3 (4.5 V to 5.5 V).[1]
- Work all five switches, and clean any that are intermittent.[7][9]
- Check the colours on a colour television in each game before touching C41 or R54.[2]
Related pages
[edit | edit source]- Magnavox Odyssey 500
- Magnavox Odyssey 500 Troubleshooting Guide
- Magnavox Odyssey 500 Capacitor Replacement Guide
- Magnavox Odyssey 500 Documentation
- Magnavox Odyssey 400 General Maintenance
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 The Magnavox Company, Service Manual No. 6506: BG7520 Odyssey, first issue, December 1976, p. 6506-1: general information (9 V 200 mA AC adaptor; Hockey, Tennis, Smash and Soccer; three styles of players; colour background and players, automatic serve, digital on-screen scoring) and the specifications table. Hosted as File:Magnavox Odyssey 500 Service Manual 6506.pdf.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Magnavox, Service Manual No. 6506, December 1976, p. 6506-3: service adjustments (the warning on current drain and IC1, score indicator position, rebound, blanking with Figure 1, the instruction not to adjust the RF section, video level, 3.58 MHz oscillator, background colour, player size balance, right wall, goal opening) and the IC basic functions. Hosted as File:Magnavox Odyssey 500 Service Manual 6506.pdf.
- ↑ 3.0 3.1 Magnavox, Service Manual No. 6506, December 1976, p. 4 (headed "6505-4" in error): voltage charts for IC1 to IC8 and transistors Q1 to Q5 (VTVM; 9 V DC at IC1 pin 2; channel 4; sound on; Tennis; lowest ball speed; players centred), with notes 1 to 16. Hosted as File:Magnavox Odyssey 500 Service Manual 6506.pdf.
- ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 The Magnavox Company, Odyssey 500 Installation and Game Rules, 1976: introduction and features (the colours of the playing fields, the three player styles and their sizes, the black spot on the left player, the reset, automatic serve and 20-point game), preparation for use (antenna-game switch, game cord, AC adaptor, channel switch, sound switch), adjusting the television, the control panel, the player control knobs and ball control, and the Smash, Tennis, Hockey and Soccer rules. Hosted as File:Magnavox Odyssey 500 Installation and Game Rules.pdf.
- ↑ 5.0 5.1 Magnavox, Service Manual No. 6506, December 1976, p. 2 (headed "6505-2" in error): typical operation (Tennis), the colours of the court and players, the black spot on the left player, the Soccer goal control, the sound switch, automatic scoring and serve, and the top view of the BG7520 with its controls and switches. Hosted as File:Magnavox Odyssey 500 Service Manual 6506.pdf.
- ↑ Magnavox, Service Manual No. 6506, December 1976, back cover: cabinet replacement parts list. Hosted as File:Magnavox Odyssey 500 Service Manual 6506.pdf.
- ↑ 7.0 7.1 7.2 7.3 7.4 Magnavox, Service Manual No. 6506, December 1976, p. 6506-9: replacement parts list (coils, capacitors with type, value, rating and part number, controls and switches, semiconductors, AC adaptor and miscellaneous) and the antenna/game switch parts list. Hosted as File:Magnavox Odyssey 500 Service Manual 6506.pdf.
- ↑ 8.0 8.1 8.2 8.3 Magnavox, Service Manual No. 6506, December 1976, pp. 6506-5 and 6506-6: BG7520 schematic diagram, with the power switch, adaptor jack J1, IC1 to IC8, crystal X1, the RF section and the antenna switch box. Hosted as File:Magnavox Odyssey 500 Service Manual 6506.pdf.
- ↑ 9.0 9.1 Nerdly Pleasures, "Sears (Atari) Tele-games Pong vs Magavox Odyssey 100 - Battle of the First Pong Consoles", 7 August 2022 (retrieved 2026-10-19): the later Odyssey models, with only the 500 and 4000 in colour; and the faults the author fixed on an Odyssey 100 (blanking adjustment, a noisy channel switch, dirty ball reset contacts). Owner's hands-on report.
- ↑ Magnavox, Service Manual No. 6506, December 1976, p. 6506-7: BG7520 top view (service adjustments), showing the adjustment controls, player controls, switches S1 to S5, IC1 to IC8, Q1 to Q5 and TP1. Hosted as File:Magnavox Odyssey 500 Service Manual 6506.pdf.