LAI Space Invaders Restore – Checking PCB & Monitor (Part 1)

Its time now to start the restoration of my LAI Space Invaders upright. LAI (Leisure & Allied Industries) is an Australian producer of amusement and arcade games. This cabinet is quite similar to the original Taito Space Invaders, using a lot of the same components. However the LAI variant is not quite as desirable as the Taito upright. I suspect that LAI built their own cabinets based on the design of Taito under licence and imported the games boards and other associated parts.

So onto the cabinet itself. This is a big project. The side art is mostly missing, the power supply is missing, the rear panel door is missing, the wheel base is broken and there are a few chunks out of the cabinet sides near the base. The control panel artwork is not good, the perspex bezel is in bad shape due to crazing, and it has been hacked to put in an MCA 2 way joystick. But its still Space Invaders right!

The first thing I will do is see what is working. The PCB is a Midway L shape PCB with a Taito sticker on it.

To test the PCB I made a harness using instruction from 

I only wired up enough connections to get a picture to start with. Now with Space Invaders PCBs you need to tie the Power on Reset (POR) pin to earth or it will not run. The kind of picture you will get is below:

The good news with Space Invaders PCBs such as this one is that they can be connected to composite on TV input. So using the reference in the Space Invaders pin out above, I created the simple circuit on some strip board. One thing to note using a CD4049 CMOS IC is that you should not leave unused inputs floating. I tied pins 5, 7, 9, 11 and 14 to pin 1 to positively switch all the unused gates LOW by applying a HIGH, (5vDC), to all the unused gates inputs.

And we have success!

You can’t tell from the picture above, but there is a ROM hack in this PCB made by LAI so the game runs as Space Invaders PT3, which looks like a clone of Space War Part Three

So a working PCB is a great start. Time to look at the monitor. All I will do for now is see if I can get a picture at all. To use the PCB in the cabinet I will need to add a new switching power supply. I won’t try to source an original midway power supply, a modern switcher is much more reliable.

Firstly I will need to tap 240v AC to power the switching power supply. I do this by adding a terminal to split the AC after it comes in from the mains. I use an item from my local Jaycar store. I snip the legs off from underneath and mount on the base of the cabinet.

On the active line into the power supply, I will use an inline fuse – 240v 3A.

I like to use spade connectors which slip onto the power supply connections, so add some spade lugs to the power supply.

After setting the power supply up, all connections have been checked and the right voltages are coming out.

Upon firing the game up with the monitor, no luck. There is neck glow on the tube, and no picture at all. There is a lot of screen burn on the tube as well. I think the best way forward won’t be to try and fix the chassis or get a replacement B+W tube. I will use a colour TV, and have one that I think will work well with some screen adjustments.

Next steps are to gut the entire cabinet and begin to fix it cosmetically!



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