G’day ladies and gentlemen! Today we’re going to have a look inside the Pioneer LaserActive PAC-S1, which is essentially a Sega Mega Drive and Mega-CD expansion unit for the Pioneer LaserActive. This is the Japanese PAC-S1, although I’d expect the American PAC-S10 to be fairly similar inside.

The long-term plan is to replace an enormous collection of ageing surface-mounted electrolytic capacitors. I reckon there could be more than seventy of the little things spread across the boards, so that’s going to be a rather exciting job. First, however, we need to get everything apart without breaking it!

I’d already opened this unit previously to dump the BIOS, so a few screws were conveniently loose. Removing the metal casing gives us a good look at the mainboard and a smaller daughterboard, both absolutely covered in components. Some of those chips should look rather familiar to anyone who’s worked on a Mega Drive.

The daughterboard comes away after removing its retaining screws and carefully separating the board-to-board connector. There are capacitors everywhere! Looking at the number of them, I suspect replacing the whole lot is going to take a while. Still, it’s rather nice to see the hardware laid out like this.

Getting the front panel off required a little more care. There were two additional screws hiding underneath, and I’m very glad I noticed them before trying to pull the plastic away. Snapping the front off a piece of hardware like this would have been a complete disaster! The controller ports are connected internally by cables, with white to the right and an orangey-yellow one to the left. The first one even rhymes! I disconnected them after noting their positions.

With the front removed, the mainboard can slide out of the metal frame once the remaining screws are out of the way. There are some interesting little details inside, including the battery, the familiar Sega processors and the BIOS EPROM. The markings on a few of the chips also suggest this particular unit dates from around 1993.

There’s a 27C1024 EPROM fitted for the BIOS, along with quite a collection of custom chips. I also spotted some fuse positions on the underside of the board that might relate to the Mega Drive and Mega-CD sections, although that’s only a guess at this stage. I’d rather confirm their function than assume I’ve worked it out from the markings alone.

The boards themselves look remarkably well put together. Unfortunately, all those capacitors are still waiting to be removed, and there’s plenty of work ahead before this unit is ready to go back together.

What a lovely piece of hardware, though. Incredible! Just fantastic!

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