Monday, January 20, 2014

Astro Invaders Arcade Restoration - Circuit Board Cleaning

Part I - Intro
Part II - Lights & Locks
Part III - Marquee Paint
Part IV - Power Supply Rebuild

circuit boards in "card cage"

Now that the game is working, I want to make sure it is working as well as it possibly can. Decades of dust and corrosion on the circuit boards, pots, and IC pins can lead to sub-optimal performance. I'm not sure if it will help, but it certainly can't hurt to give everything a good cleaning.

(L to R) video, CPU, & sound boards

I started by pulling out the card cage containing all of the circuit boards. I sprayed each with circuit cleaner and scrubbed them with a soft toothbrush.  Any IC's that could be removed were worked back and forth in the sockets to clean the pins. There are 8 exposed potentiometers on the sound board. One is the master volume and then I believe each game sound has it's own volume control. I marked the position of each one with a silver Sharpie before cleaning . Then they were sprayed with contact cleaner/lube and worked back and forth. I found a capacitor and resistor whose leads were touching and perhaps causing problems. I corrected that and checked for the same problem on the rest of the components. I finished up by cleaning the board contacts with 0000 steel wool. As I worked I looked closely for any signs of failing components. Everything looked good. I blew the boards dry with compressed air, cleaned the card cage and put it all back together.

someone didn't want to find an adapter for the ground plug

cracked power cord

While I was at it, I changed the power cord. The ground pin was broken off of the plug and the cord was starting to crack. I was going to pick up some 3 lead cable and make my own power cord. But buying wire by the foot is expensive. So instead I purchased an extension cord. With the plug molded in, the cord looks more professional anyway.

I kept the cord 11 feet long, like the original. I just cut off the female end and wired the cord to the connector with some new female crimp terminals. I kept the original warning card in place and added a zip-tie as a strain relief. The new power cord is much heavier duty than the original. In fact, if I were doing it again, I would probably go with 16 gauge wire. It was hard getting the 14 gauge wire into the connector. But this will stand up to years of hard use.

new cord in place

Luckily the game still works and it seems like the sound is less scratchy than before. The game also used to have a few errant pixels lit up on the screen during game play. That seems to be gone as well. Next up I'll pull out the control panel and restore that.

PS - I didn't even waste the cut portion of the extension cord.

Extension Cord   $15.96

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