My Space Station has the bug where 75% of the time, at the first power on you'll either get no displays or a random error... but an immediate flick of the power switch boots the game normally and it plays 100% fine for however long you want, hours on end. The other 25% of the time it boots fine on the first attempt. It's done this for nearly a year.

I finally stumbled on the solution to this problem in the Sys11 club thread: replace the 22uF/25V cap at C30. Ha! Too easy to ignore, so I did this.

When I installed the repaired board and turned the game on, it failed to boot, I heard a coil pop then fuse F5 on the power supply blew. Using a 7A breaker in this location, it immediately trips when I try to start the game. During repeated cycle troubleshooting / while removing loads from the PSU, eventually F6 blew as well. Even with all loads disconnected from the PSU, F5 still blows.

Confirming a suspicion, I consulted the tech guides and say this indeed means that the PSU bridge rectifier has shorted out. OK. I can test and replace that, but...

... is this just a wild freaking coincidence, or could something I might have botched (and for god's sake I'm afraid to ask what?) in replacing one stupid cap at MPU C30, have caused this? (In other words, if I fix the PSU and hook it back up... could it blow again?)

That was the first thing I thought but no, I did not. Checked and re-re-re-checked.

But let's say I did: would that blow the BR on the PSU?

Well, I feel a little better that it's not something I did, since the MPU boots on the bench...

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So here's something interesting. Even on the bench, it looks like it still doesn't always boot at the first power-on: the 5V and Diag LEDs stay solid with no blanking light. Flick the switch again, and I see normal bevahior (5V and Blanking LEDs on with Diag LED flashing). So it seems C30 was not the sole problem. Any further ideas?

As for the PSU rectifier, I have a couple spares so hopefully I can try that tonight. Look like beefy traces to deal with and those are always a bear to desolder. Anyone have any tips to share? Is a 400V 30A rectifier too high (originals were 100V but I presume that like caps and diodes, a higher V rating is OK).

Fuse breakers are awesome. I'd compiled a set in a Mouser order of 2, 2.5, 3, 4, 5, 7, 8, and 10A breakers, and they've paid for themselves since then.

I didn't mention: I'd rebuilt the power supply a few months ago, as I have 3 others with no issues. Never had to touch a PSU rectifier yet.

Apparently there's a first time for everything, so I replaced the rectifier tonight, put the PSU with the breakers in the game, connected the transformer leads, turned it on, and... nothing happened - meaning the breakers didn't trip (whew). Hooked up GI and that worked. Connected the MPU I worked on and... it booted. Played a test game through and all was well!

So yeah: what a freaking coincidence!?!

(I've had too many of these things in my life lately: day job, car repair, pin repair - seems everything I fix lately, something kinda-sorta-but-not-directly related immediately blows up. I don't know who I pissed off to throw my karma out of whack, but screw it: today I got stuff fixed at work, got the Aerobarge running again, and got this thing knocked out. I'm having a beer!)

For some reason I do it all the time...