Starting Astro Invaders Restoration - Help Needed

[entomophile]

A friend of mine gave me a few arcade games, one of them being Astro Invaders.  It was working sporadically, usually taking a whack to the side to get it going.  Now when I power it up it just makes a "pew, pew pew..." sound and the screen has the static image in the attached picture.  I was going to sell it but I decided to try and restore it instead.

This will be my first restoration.  I plan on doing a step by step troubleshoot.  But I figured I would check here first to see if my symptoms were indicative of anything obvious.

Thanks for any help.  I'm hoping you guys can help me get this classic back in shape!

[entomophile]

OK.  So I started to dig into the power supply.  First, it was loose in the cabinet.  I screwed it back down to the mount with some 6-32 screws.  Then I checked all of the fuses and found one fuse mount was loose.  I bent that to make it tight.  Then I started checking the voltage test points.  The 5V pot was out of adjustment (it was reading about 1.3V).  I adjusted that up to 5.3V as specified in the manual and the game worked...briefly.  I managed to play one life.  When my ship blew up the game blanked out.  I checked the other voltage test points and found the 12V and 15V supplies are way out.

I am guessing it is the capacitors or the voltage regulators.  Anyone know how to determine which is at fault?

[entomophile]

Guess I'll just keep talking to myself    I checked the voltage regulators and the voltage out was as expected.  Checked the voltage test points and they tested fine this time.  Game appears to be working for now.  I think I'll let it run for a while then start cleaning all of the circuit boards, switches, connectors, etc.

[Paladin]

Replacing caps is always a good idea.  The largest ones on that power board may be tough to find.  I'd suggest replacing the smaller ones first if the game stops working again, then worry about the larger ones.

The first thing I'd do is check the connector that your multimeter is hooked up to in the photo.  I can see some heat damage by the diodes and connector.  A common problem with those power connectors is that the pins in the connector loose spring tension over time.  The loose pins create resistance which in turn creates heat and further damages the header on the board and the pins in the connector.

Standard procedure is to cut off the pins in the plastic connector and install new ones.  Trifuricon are best because they have 3 sides that grip the header posts instead of just one.
When you replace the pins you want to replace the header assembly on the board as well due to the damage caused by overheating.

The pins and header are available from several online sites.  If there's a Fry's near you they will probably have the header, but not trifuricon pins.

[entomophile]

Actually, that's not my multimeter.  That is a jumper wire someone installed to replace a broken pin on the connector.  Turns out, it looks like most of the problems were caused by a loose connector from the SG323 regulator (upper left corner in the picture).  Thanks for the advice on the Trifuricon connectors.  I was wondering what to use to replace those.  I think I may replace the caps anyway.

[jennifer]

    Id take a close look @ the edge connectors on the board, a problem here will create random signal/ground problems.

[entomophile]

    Id take a close look @ the edge connectors on the board, a problem here will create random signal/ground problems.

Thanks.  My next step will be cleaning all the circuit boards, connectors, and switches.