Grandstand Model 6000 General Maintenance

The base of a Grandstand 4600. Photographs of two Model 6000s show a base laid out the same way: sliding battery cover with two arrow marks, raised label panel, two screws beside the front feet, and a housing on one side. No freely licensed photograph of a 6000 has been found.

The Grandstand Model 6000 (booklet title Adman Grandstand T.V. Game Model 6000; panel name GRANDSTAND 6000 COLOUR) is a ten-game colour TV game made in Hong Kong and dated 1978 by the Centre for Computing History. Its bats are moved with an X-Y joystick on each control pod, so they can move across the screen as well as up and down. No Grandstand manual or schematic for the 6000 has been published, and no photograph of its board has been found. The sources are a collector's photographs and notes on two 6000s, the museum record, what is known of the Grandstand Model 4600, which uses the same style of case, and General Instrument's 1978 data for the AY-3-8610, the chip whose ten games the 6000 matches.

Fault-finding is on Grandstand Model 6000 Troubleshooting Guide.

The 6000 at a glance

What is known about the Grandstand 6000

Feature	Detail	Source
Panel	GRANDSTAND 6000 COLOUR; LEFT and RIGHT score sliders marked 0 to 10; ten-position game slider
Switches	POWER (ON/OFF), GAME RESET, TEAM L. and TEAM R. (AMATEUR/PROFESSIONAL), SPEED, SERVE (MANU/AUTO)
Control pods	A joystick and a red SERVE/FIRE button on each pod; the pods lift out of their bays but stay wired to the console
Base label	UHF channel 36, PAL system; six UM-2 cells or a 9 V DC 100 mA adaptor; made in Hong Kong
Sockets	RF lead and DC 9V socket at the rear; a blanked-off round socket on one side near the back
Box	GRANDSTAND 6000 DE-LUXE COLOUR VIDEO SPORTS CENTRE, "Multi-movement X-Y Joystick Hand Controllers with target shoot"

The game chip

No photograph of a 6000 board has been published, so the chip is not confirmed. The evidence points strongly to General Instrument's AY-3-8610 "Superstar":

• GI lists the AY-3-8610's ten games as tennis, hockey, soccer, squash, practice, gridball, basketball, basketball practice, and one- and two-player target. The 6000's ten games are the same: Basketball Practice, Practice, Tennis, Basketball, Squash, Hockey, Soccer, Gridball, Target Twin and Target Practice.
• The AY-3-8610 moves each player in two axes, matching the X-Y joysticks.
• It has a separate bat-size input for each player, "for handicapping", which matches the TEAM L. and TEAM R. switches, and a high-speed inhibit input, which matches SPEED.
• Its target games are played by moving a cursor and pressing the serve button to shoot, with no light gun. The 6000's buttons are marked SERVE/FIRE, its box promises "target shoot" from the joysticks, and the gun socket found on other Grandstand models is blanked off.

Pong-Story describes the related AY-3-8600 as having eight bat-and-ball games and two shooting games, and says the differences between it and the AY-3-8610 are unknown. Whichever it is, read the chip's marking when the case is open: no 6000 board has been photographed.

Before you start

• Take out the cells and unplug the adaptor.
• Lift both joystick pods out of their bays so their leads are free.
• You will need a cross-head screwdriver, a multimeter, isopropyl alcohol, switch cleaner, potentiometer cleaner and a soft brush.

Opening the case

The 4600's pods, lifted out of their bays on their leads. The 6000's joystick pods lift out in the same way.

No photograph of the inside of a 6000 has been published. Its base matches the 4600's, whose owner gives the order for opening it.

1. Slide off the battery cover in the direction of its arrow marks. On the photographed 6000 the cover carries two foam pads that hold the cells in place.
2. Take out the six cells. Two screws sit in the floor of the battery compartment, beside the springs. Remove them.
3. Turn the console over and remove the two screws beside the feet at the front edge of the base.
4. Lift the base away slowly. On the 4600 the board is fixed to the upper case by five screws, and the controller leads and the DC socket are wired to it. Expect the same on the 6000, and photograph everything before going further.

One owner found something loose rattling inside a 6000 that gave only a blank screen. If yours rattles, find the loose part before powering it: a loose screw or broken-off part can short the board.

Cleaning

• A lightly dampened cloth with a drop of detergent is enough for the case and the joystick pods. Keep solvent off the printed metal game plate and the panel lettering.
• Ian Hill's second 6000 has faded compared with his first, which is in immaculate condition, and the pictograms on its game plate are worn. Clean gently and do not scrub the printed areas.
• Clean the rear DC 9V socket and the RF plug.

Power: cells, adaptor and polarity

• Six 1.5 V UM-2 (C) cells. In the photographed compartment four lie in one row and one at each end of the second row, with a fabric ribbon for lifting them out.
• The label asks for a 9 V DC adaptor rated 100 mA; the socket at the rear is labelled DC 9V.
• No 6000 source gives the polarity. The 4600, with the same label, is centre positive according to its owner. Measure the 6000's socket against the battery terminals before trusting that.
• A Grandstand A.C. adaptor came with the photographed 6000: 240 V in, 9 V 150 mA out, double insulated, made by Adman Electronics of Harrogate. At 40-plus years old, check its case and lead for cracks before plugging it in, and measure its output.
• If the chip is an AY-3-8610, it runs from +6 to +7 V and must never see more than +12 V on any pin.

Remove the cells for storage: leaking cells corrode the contacts, the power socket and the RF connector.

Joystick pods

Each pod has a joystick that moves its player's bat in two directions, and a SERVE/FIRE button. In GI's reference design for the AY-3-8610, each joystick drives two potentiometers, one per axis, each working with a capacitor to set the bat's position, and GI warns that the joystick controls "must be chosen for maximum adjustment for full control of bats to be shown on TV receiver".

• A bat that drifts, jumps or will not reach one edge of the screen points to the potentiometer for that axis. Open the pod and clean both potentiometers with potentiometer cleaner, moving the stick through its full travel.
• A bat that moves on one axis only means one potentiometer, or its wire in the pod lead, has failed.
• If a stick no longer moves through its full travel, its bat will not reach the edge of the screen. Check the mechanism as well as the potentiometers.
• If SERVE/FIRE stops working, clean its contact and check its wires in the lead. On the AY-3-8610 each serve input works by being connected to ground, with no more than 1 kΩ through the contact.

Switches and score sliders

• The panel's five slide switches and the ten-position game slider all set the game chip's inputs. GI asks for 1 kΩ or less through a closed contact on the AY-3-8610. Clean each with switch cleaner and work it end to end.
• The game slider on the second photographed 6000 has a worn plate; check that its contacts still meet in each position.
• The LEFT and RIGHT sliders are manual score counters, as on the 4600.

RF output

The label gives UHF channel 36, PAL. The RF lead is fixed and leaves the rear of the case.

Wearing parts

What wears on a 6000

Part	Why	Check
Joystick potentiometers (four in all)	Moved constantly in two axes	Clean; check full travel on screen
Joystick mechanism	Must give the potentiometers full travel for the bat to reach the screen edge	Check the stick reaches both ends of each axis
SERVE/FIRE buttons and pod leads	Used every game; leads flex as pods are lifted out	Clean; check each wire
Slide switches and game slider	Contact resistance rises; the chip needs 1 kΩ or less	Clean; measure closed
Battery contacts and the DC 9V socket	Corrode if cells leak	Remove cells for storage

Storage

• Remove the cells.
• Seat the pods in their bays with the leads loosely coiled.
• Keep the console dry and out of direct sun.

Preventive maintenance checklist

1. Shake the console gently and listen for loose parts before powering it.
2. Take out the cells and look at the contacts.
3. Confirm the adaptor gives about 9 V with the polarity the 6000's socket expects.
4. Clean both joysticks' potentiometers and the SERVE/FIRE buttons.
5. Clean the five slide switches and the game slider.
6. Tune an analogue television to channel 36 and check that each bat reaches all four edges of its area.
7. With the case open, write down the game chip's marking and the electrolytic capacitor values: neither has been published for the 6000.

Related pages

• Grandstand Model 6000
• Grandstand Model 6000 Troubleshooting Guide
• Grandstand Model 4600 General Maintenance, whose base and case match the 6000's
• Grandstand Model 5000 General Maintenance, the motorcycle-game model in the same style of case
• Grandstand Universal Mains Adaptor
• Battery Explosion, Capacitor or Corrosion Damage