Grandstand Model 6000 Capacitor Replacement Guide

Inside a Grandstand 4600, the six-game model in the same style of case as the 6000; this is not a 6000. The board is fixed solder side up to the upper case, with the control-pod leads coiled into the bays either side. No photograph of the inside of a Grandstand 6000 has been published.

The Grandstand Model 6000 (panel name GRANDSTAND 6000 COLOUR) is a ten-game colour TV game with an X-Y joystick on each control pod, made in Hong Kong and dated 1978 by the Centre for Computing History. No photograph of its board, no parts list and no schematic has been published, so none of its capacitors is known. Its ten games, joysticks and switches all match General Instrument's AY-3-8610 "Superstar" chip, and GI published a complete colour console circuit for that chip, with a 9 V supply like the 6000's. That circuit, labelled as GI's, is the best guide to what a 6000 board needs from its capacitors. Below it are the 6000's own supply details, how to open it, and how to record and recap its board.

Care is on Grandstand Model 6000 General Maintenance; symptoms are on Grandstand Model 6000 Troubleshooting Guide.

What is known for the 6000

• Base label: UHF channel 36, PAL system; six UM-2 (C) cells or a 9 V DC 100 mA adaptor; made in Hong Kong. The adaptor socket at the rear is labelled DC 9V.
• A Grandstand A.C. adaptor came with one example: 240 V in, 9 V 150 mA out, made by Adman Electronics of Harrogate. No source gives the socket's polarity.
• Each joystick pod has a SERVE/FIRE button; the panel has GAME RESET, TEAM L. and TEAM R. (AMATEUR/PROFESSIONAL), SPEED and SERVE (MANU/AUTO) switches and a ten-position game slider.
• One 6000 gives only a blank screen and has something loose rattling inside; it was undiagnosed when described. Nothing points to the capacitors in that report.
• No capacitor value, position or failure has been published for a 6000.

General Instrument's AY-3-8610 colour console

GI's System Diagram 2 for the AY-3-8610 is a full-colour console with the AY-3-8615 colour converter, fed from "BATTERY OR AC ADAPTOR 9V 150mA". These are its capacitors. They are GI's values for GI's circuit, not readings from a 6000:

Capacitors in GI's AY-3-8610 System Diagram 2

Function	GI's part	Type	Notes
Supply regulator input	2.2 µF	An electrolytic-sized value; drawn without polarity marks	Across the 9 V input
Supply regulator output	2.2 µF	An electrolytic-sized value; drawn without polarity marks	Transistor regulator set by a 6.8 V zener diode and 150 Ω; the ON/OFF switch follows it
Supply decoupling after the switch	0.01 µF	Small
Video coupling	22 µF	Electrolytic; drawn with polarity marks	Couples the colour converter's video output to the 2N3904 stage feeding the modulator
Modulator feed	0.1 µF	Small	With 22 Ω, at the Astec UM1082 modulator
Joystick horizontal axes	0.22 µF each	Small	With a 100 kΩ potentiometer and 82 kΩ
Joystick vertical axes	1000 pF each	Small	With a 100 kΩ potentiometer
Game-select and control lines	0.01 µF each	Small	Marked "ALL .01 µF"
Colour crystal	10 pF and a 3-15 pF trimmer	Small	3.579545 MHz crystal at the colour converter

From GIMINI TV Game Circuits, p. 27, examined at full size. GI gives the AY-3-8610 a supply of +6 to +7 V, at most 60 mA at +7 V, and never more than +12 V on any pin. In a circuit like this the 22 µF part and, by their value, the two 2.2 µF parts are the electrolytics; the two 2.2 µF parts sit either side of the regulator that feeds the chip.

GI's diagram runs its colour converter from a 3.579545 MHz crystal, the NTSC colour frequency, while GI's application notes build PAL colour round a 4.43 MHz crystal. The 6000 is a PAL console, so expect its colour section, and perhaps its colour chip, to differ from GI's.

The 4600 board, for comparison

The Grandstand Model 4600, in the same style of case, has a photographed board: nine radial electrolytics and a large unmarked white cylinder, C-numbers printed beside the parts, and two legible markings, C38 10 µF and C37 16 V. The 4600 uses a different game chip, the AY-3-8500, and controllers that move the bats in one direction only, instead of joysticks, so its parts list is not the 6000's. Its positions are listed on Grandstand Model 4600 Capacitor Replacement Guide.

Signs of trouble

• Bulging, leaking or split electrolytics, or deposits round their leads; the 4600 in the same style of case has brown deposits on and around several parts.
• A picture that rolls or shows hum bars, or a chip supply outside GI's +6 to +7 V, once the cells or adaptor have been checked: suspect the supply electrolytics. See Capacitor Failure Symptoms.
• A rattle inside. Find the loose part before powering the console; a loose screw or fragment can short the board. Loose debris can also come from a burst capacitor, so look at the board where the part was found.
• Leaked cells: see Battery Explosion, Capacitor or Corrosion Damage.

Recording a 6000 board

No 6000 board has been described in public. When you open one:

1. Photograph both sides of the board and every wire to the pods and the DC socket.
2. Record the game chip's full marking, and any colour chip beside it: whether the 6000 uses GI's AY-3-8615 colour converter is not known.
3. Record each electrolytic's position and C-number if printed, its capacitance, voltage, maker, size and stripe side. Note which ones sit by the DC socket and power switch: those are the supply parts.
4. Check each capacitor you take out on an ESR or capacitance meter.

Opening and recapping

1. Slide off the battery cover in the direction of its arrow marks. The cover on the photographed 6000 carries two foam pads.
2. Take out the six cells, lifting them with the fabric ribbon. Remove the two screws in the floor of the battery compartment.
3. Turn the console over and remove the two screws beside the front feet.
4. Lift the base away slowly. On the 4600 the board is held to the upper case by five screws, with the pod leads and DC socket wired to it; expect something similar, and photograph everything before going further. The joystick pods "are removable, but not detachable", so keep their leads slack.
5. Replace one capacitor at a time: read and record it, desolder it with a pump or braid, clean the holes, and fit a new part of the same capacitance and the same or higher voltage, rated 105 °C, with the same lead spacing and polarity, no taller than the original.
6. Put the board back so every switch and the game slider pass through their slots, then screw the base on.

Recommended tools and parts

• A temperature-controlled soldering station, a pump or wick, flux and isopropyl alcohol.
• Meters: a multimeter, plus a capacitance or ESR meter for the removed parts.
• Radial 105 °C electrolytics from Nichicon, Panasonic, Rubycon or another current maker, chosen from what the 6000's board carries.
• A current-limited 9 V bench supply, with its polarity checked against your console's socket and battery terminals. See also Recommended Tools.

Checks after recapping

After recapping a 6000

Check	Expected	Source
Supply at the DC 9V socket or the cells	9 V DC; label rating 100 mA
AY-3-8610 pin 16 (VCC) to pin 1 (VSS), if fitted	+6 to +7 V; 60 mA at most at +7 V
Picture	Colour on UHF channel 36, PAL, steady
Joysticks	Each bat moves across and up and down the screen; SERVE/FIRE works, including in the target games
Switches	GAME RESET, TEAM L., TEAM R., SPEED and SERVE change play; the game slider selects all ten games

Related pages

• Grandstand Model 6000
• Grandstand Model 6000 General Maintenance
• Grandstand Model 6000 Troubleshooting Guide
• Grandstand Model 4600 Capacitor Replacement Guide, in the same style of case
• Grandstand Colour Programmable SD070 Capacitor Replacement Guide, another Grandstand console whose AY-3-8610 sits in a cartridge