June 15, 2019

Repairing an Astro Wars

I had an Astro Wars as a kid and loved it. The VFD display used in toys and cars from the 1980s have a really lovely glow about them. Much richer than an LCD display.

Last year I picked up an old 1981 Grandstand Astro Wars that wasn’t working. I was hoping the issue would be something simple like a corroded battery connector or a broken wire or something. It turned out to be a bit trickier.

I cleaned and checked all the connections and tested that current was getting to the board. No problems there. After that I noticed that the large transistor S02 got quite hot.

I removed the transistor and tested the with a component tester. The seemed to be OK, but then transistors are a dark art - so I decided to order some replacements. It can be tricky finding components that compatible with the original components. Unsurprisingly electronics have come along way, companies have folded and the same models are not always available.

I then proceeded to test all the other components and replace all the electrolytic capacitors (which I could get at a local electronics store). They are really cheap and it seemed to makes sense to replace them while you have the hood open.

The replacement transistors arrived and I replaced the S02 transistor. I turned on the Astro Wars and it worked! I enjoyed playing it, the kids enjoyed it. And then about a month later it stopped working again.

It appears that the S02 transistor had failed again. And the small transistor S03 in the bottom right was also getting hot. So I replaced the S02 again, but it still didn’t work.

Then one day I came across this video on youtube. It suggested replacing the mysterious S06 component - which is a Zener Diode (140v 500mw). Now these thing are rare. I ordered some from an ebay seller in the UK.

Eventually they arrived and I replaced the S06 zener diode (and the S02 transistor again for good measure). Now when I power up the device the music starts, but the screen doesn’t turn on. Rats.

I think I need to work out what the S03 transistor is and order some.

To be continued…