Invader From Space is one of the older Grandstand games, this one is from 1980. Although I never owned one of these back in the day I remember playing it a lot. I picked this one up from Ebay for £20, not a huge bargain but they do go for a lot more sometimes.  I got the box, the guide / insert but is a bit battered and missing the polys.

My device has a serial number of “5/13409”. 

The seller on ebay mentioned that it had some corrosion in the battery compartment and was not working. I was pretty convinced it would be easy to fix.

It is pretty grubby on closer inspection and it does have signs of rust and corrosion inside the battery compartment but it was not terrible.

The first thing I tried was to clean up the battery compartment a bit. In order to remove the battery terminals I needed to open up the game and desolder the black and red wires from them which allowed me to remove the terminals completely.

Then the clean up involved little more than a cotton bud and bit of alcohol. I also used sand paper to clean the terminals and remove the rust.

However this did not get the game working. The game was still completely dead. Inside it looked in good clean condition.

I think the VFD in these are beautiful things. They seem to have the circuits printed inside of them and are attached to the PCB with a number of pins / legs.

There seemed to be no power to any of the main components and my guess was that someone had tried a mains adapter with the wrong voltage and or polarity. This was very very common on these things. This would mean one of the transistors would likely have blown.

The main transistor in this circuit is S02 which is an NEC D882 NPN transistor. I took this out of the circuit and indeed it was faulty and was testing as open in all directions.

I found a replacement on ebay for 29 pence.

Additionally I discovered that the DC mains socket / switch was also faulty. This switch prevent current flowing back to the batteries when the mains adapter is plugged in.

Again a simple 40 pence replacement ordered from RS components.

While it was open I decided to dismantle the front panel in order to be able to clean it up a bit. I did this was soap and water and a tooth brush.

So cleaned and reassembled the moment of truth!

Works perfectly, loud clear sound, plays really well.  Very very simple fix.