Grandstand TV Game 3600 General Maintenance

Pin configuration of General Instrument's AY-3-8500. The TVG 3600's six games and switch settings are the ones this chip provides, but no photograph of a TVG 3600 board has been published, so the chip fitted is not confirmed.

The Grandstand TV Game 3600 (front strip "Adman GRANDSTAND TVG 3600") is the first model of Grandstand's 3600 series: a black six-game Pong console with a pistol, listed by Wikipedia as a colour console made in Hong Kong between 1977 and 1979. One example is on record, in the South-West Retro Computing Archive, photographed from the front only. No manual, service information, label or inside photograph has been published, and the later 3600 Mk II and Mk III use a different case, so their opening procedures do not carry over. What can be done with the available evidence is set out below: the TVG 3600's controls, controllers and pistol as the photographs show them, the supply questions to settle before powering one, and what to record when you open one.

Fault-finding is on Grandstand TV Game 3600 Troubleshooting Guide; the electrolytic capacitors are covered on Grandstand TV Game 3600 Capacitor Replacement Guide.

What is known and what is not

TVG 3600: published facts

Part	Detail	Source
Panel	Six slide switches (POWER, SOUND, SPEED, ANGLE, BAT SIZE, SERVE), MANUAL and START buttons, six-position game slider
Sockets	One strip on the front of the panel: LEFT PLAYER, PISTOL (two sockets), RIGHT PLAYER
Controllers	Two black cylinders with knurled knobs, plugged in on leads
Pistol	Black with a brown grip, two plugs
Picture	Colour, according to Wikipedia
Game chip, supply, polarity, channel, screws	Not published: no base, label or inside view exists in any source found	None found

Before you start

• Turn the console over and read the label on the base before connecting anything. It is the only source for the supply voltage and current.
• No source gives the TVG 3600's supply. The 3600 Mk II that followed it is labelled for six UM-2 (C) cells or a 9 V 100 mA adaptor, but it is a different design, so treat that only as a guide until your own label confirms it.
• Remove any cells, and unplug the controllers and the pistol.
• Tools: a cross-head screwdriver, a camera or phone, isopropyl alcohol, a soft brush, switch cleaner, potentiometer cleaner and a multimeter.

Opening the case

No account of opening a TVG 3600 has been published, and no photograph of its base exists in any source found. Work from what you can see:

1. Take out the cells and look inside the battery compartment for screws before turning to the rest of the base.
2. Look for screws under any rubber feet and labels before prising anything; on Grandstand's 3600 Mk II two of the four case screws sit in recesses beside the feet, but the TVG 3600's base may differ.
3. Lift the case apart slowly. The speaker sits behind the grille in the middle of the panel and the sockets are on their own strip below it, so expect leads between the board, the speaker and the socket strip.
4. Photograph both sides of the board and every lead before unplugging or desoldering anything.

When you have it open, record what you find: the game chip's markings and date code, the crystal markings, any colour-encoder chip, the RF modulator and any channel marking, the board's printed number, and each electrolytic capacitor's value and voltage. None of this has been published for the TVG 3600.

Cleaning

• Wipe the black case with a damp cloth and a little washing-up liquid. Keep it off the brushed silver strip across the top and the silver socket strip, whose legends are printed on.
• The speaker grille is a set of horizontal slots in the panel. Brush the dust out of them; do not wash them, because water would run onto the speaker behind.
• Clean the board, once open, with isopropyl alcohol and a soft brush.

Switches, slider and buttons

The panel has six slide switches: POWER (ON, OFF), SOUND (ON, OFF), SPEED (H, L), ANGLE ("20°/40°" or "20°"), BAT SIZE (L, S) and SERVE (AUTO, MANU). The yellow MANUAL and blue START buttons sit below them, and the games are chosen with one six-position slider at the right.

If the chip is General Instrument's AY-3-8500, as the games suggest, every setting and every game is chosen by connecting one of its inputs to ground, and GI allows no more than 1 kΩ through a closed contact; START would be the reset input that clears the scores, and MANUAL the manual serve. A dirty switch therefore shows up as a setting that will not change.

• Spray a little switch cleaner into each slide switch and work it a dozen times.
• The game slider has six positions. If it rests between two of them, the AY-3-8500 sees no game selected and plays a hidden football variant with a third bat on the right. Clean the slider contacts and check that it clicks into each position.
• Clean the two button contacts.

Hand controllers

The two black cylindrical controllers plug into the LEFT PLAYER and RIGHT PLAYER sockets on the strip below the speaker grille. In the AY-3-8500's reference circuit each bat is set by a potentiometer feeding an R-C network, with 1 MΩ potentiometers and a 10 kΩ resistor in series; the values in the Grandstand controllers have not been published.

• A bat that jumps usually means a dirty potentiometer track. Open the controller, spray potentiometer cleaner into the track and turn the knob end to end.
• Because both controllers plug in, swapping them over tells a controller fault from a socket or console fault.
• Clean the plugs and sockets, and check each lead where it enters the cylinder.

Pistol

The archive's TVG 3600 has a black pistol with a brown chequered grip and a long barrel with a cap at the muzzle. Its lead ends in two plugs, which go into the pair of sockets marked PISTOL, one small and one larger, between the two controller sockets. It is not the Thundercolt Super Marksman 304 supplied with the later Mk II.

• Keep the lens behind the muzzle clean, and check the trigger switch and the lead.
• Clean both plugs and both PISTOL sockets; a dirty contact in either can stop the shooting games working.
• The pistol responds to light from a cathode-ray tube television. Test it on a CRT set, not a flat-panel one.

Power

• Read the supply and current from the base label.
• Measure the polarity of the adaptor socket against the battery terminals before connecting an adaptor. No source gives it for the TVG 3600.
• A Grandstand-branded adaptor found with a 3600 Mk II is rated 9 V 150 mA with the tip of its 3.5 mm plug positive, and has a polarity-reversing connector in its lead; check how any such connector is set before use.
• The Grandstand Universal Mains Adaptor sold for Grandstand's handheld and tabletop games has a polarity switch, and the tabletop leaflets set it to negative. Check its setting with a meter before using it on a TV game.
• An original mains adaptor is the only part that carries mains voltage. Check its case and lead for cracks before plugging it in.
• Remove the cells for storage; see Battery Explosion, Capacitor or Corrosion Damage if they have leaked.

RF output

No source gives the TVG 3600's channel. General Instrument's application notes for the AY-3-8500 give UHF channel E36 (591.25 MHz) as one of the two standard modulator channels, so start the search there on an analogue UHF tuner; a television with only a digital tuner will not show the picture.

If your console has a colour circuit, as Wikipedia's listing suggests, it will need a 4.43 MHz colour subcarrier held within ±50 Hz of 4.433619 MHz, which GI's notes give as the limit for an average colour set. Do not turn any trimmer or adjustable coil near a crystal without marking its position first and measuring the result with a frequency counter.

Wearing parts

What wears on a TVG 3600

Part	Check
Six slide switches and the game slider	Clean and work each one; check the slider seats in each position
MANUAL and START buttons	Clean the contacts
Hand controllers and their leads	Clean the potentiometers; swap to compare
LEFT PLAYER, PISTOL and RIGHT PLAYER sockets	Clean; check for loose sockets
Pistol	Lens, trigger, lead and both plugs
Electrolytic capacitors	Not documented; see Grandstand TV Game 3600 Capacitor Replacement Guide
Battery contacts	Remove cells for storage

Storage

• Remove the cells.
• Unplug the controllers and the pistol and coil their leads loosely.
• Keep the console dry and out of direct sun.

Preventive maintenance checklist

1. Read the base label, then measure the adaptor and the socket's polarity.
2. Clean the six slide switches, the game slider and the two buttons.
3. Clean the potentiometer in each hand controller, then swap the two over and compare.
4. Clean the pistol, its two plugs and the PISTOL sockets.
5. Tune an analogue television and try all four bat-and-ball games, then both shooting games with the pistol on a CRT set.
6. If you open the case, photograph the board and record the chip, crystals and capacitor values.

Related pages

• Grandstand TV Game 3600
• Grandstand TV Game 3600 Troubleshooting Guide
• Grandstand TV Game 3600 Capacitor Replacement Guide
• Grandstand TV Game 3600 Mk II General Maintenance, the next model, in a different case
• Grandstand Universal Mains Adaptor
• Battery Explosion, Capacitor or Corrosion Damage
• Recommended Tools