Taito Space Invaders Cocktail PCB + Power Supply voltage measurements

Taito Cocktail Space Invaders PCB + Power Supplyvoltage measurements

last updated June 24, 2016

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INTRO : In order to confirm the correct operation of your space invaders cocktail, or to determine which major part is at fault, it is neccesary to measure the voltages coming fromyour power supply. The easiest and safest way to do this, is the main aim of this page.
Taito Machines this is applicable to: - Space Invaders (TVN) - Space Invaders Color (CVN) - Space Invaders Part II (PVN) (please note there are some slight differences) - Lunar Rescue - Zenitone Invaders Revenge (and other rom hacks on SI hardware)
WHAT YOU WILL NEED: - a Multimeter, doesn't have to be too fancy, anything that measures DC voltages - about 10 minutes of your time
Firstly, open your cocktail table and locate the game pcb on the left hand side.
The [G] connector is nearest to you, the [T] connector is plugged into the lower pcb at the opposite end to the [G] connector. We are starting our measurements at the [G] connector, you do not need to unplug anything at this time, you simply probe the gold pads on the pcb with the power switched on. Do not touch anything in the right hand side of the cabinet, there are live and exposed voltages here, you risk electrocution if you do. The pin numbering starts with 1 on the left, count up towards the right to find your pin number. Place your BLACK probe on either pins 1, 2 or 3 (either is fine, BLACK wires) and then follow the instruction table below, moving the RED probe:

photo	Pin	harness wire colour	voltage	acceptable range	used for
	5	Blue	12v	11.1->12.8	voltage for sound op-amps
	7	Grey	18v	11v->20v OR 0v for Space invaders part 2	Audio amplifier. Depending on how your cabinet is wired, this might be wired to the 12v which is fine. *IMPORTANT* SPACE INVADERS PART II PCBS do not use this voltage or pin. You may read a voltage but it is not needed for correct operation.
	9	Red	5v	4.9 -> 5.1	TTL Logic
	10	White	POR	0v->0.1v	Power-on-Reset signal, this must be logic level LOW for the game to boot and run, ie it should be close to 0v.

Now you have done the [G] connector measurements, you need to do the same for the [T] connector. Because this connector is hard to get to, it is neccesary to unplug the [T] connector to get at it.

Because it is not wise to have the pcb powered up with just one connector, you should unplug the [G] connector at this time as well.

Ignore the [G] connector for now, you need to take measurements on the [T] connector as indicated in the table below.

CAUTION - be careful not to force your probe leads into the T connector, this can bend or break the pins inside the housing causing a bad connection when you re-connect. Just touch them on.

The pin numbering starts with 1 on the RIGHT, count up towards the LEFT to find your pin number. place your black probe on pin 15 (BLACK WIRES) and then follow the instruction table below moving your RED probe:

photo	Pin	harness wire colour	voltage	acceptable range	used for
	1,2	RED	5v	4.9 -> 5.1	TTL Logic
	3 or 4	Blue	12v	11.1->12.8	RAM and op-amps
	5	Brown	-5v	-4.9v -> -5.1v	RAM

Summary

And thats just about it! If you have measured everything described on this page correctly and your game still doesn't boot up, then your game pcb is probably bad. If you are not measuring what you see above then your PSU will be bad, but also your game pcb could also be bad as well.

I do repair these pcbs on a regular basis, so please enquire if you need assistance. I do also sell working pcbs and parts and will take your faulty pcb as a trade-in against a fully working board.

Andys-arcade

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These pages are (C) Andy Welburn 1996-2002. I cannot be held responsible if the information supplied herein results in a blown monitor/power supply/house fuse/mind. Oh yeah, have a nice day :)