I'm taking on my first "project" pin, a Data East Secret Service, and was hoping to get some advice on the general process to troubleshoot this game (and pins more broadly).

The prior owner noted that he plugged it in and powered it up once briefly and noted that it made a humming sound (seems to be standard for DE games, working or otherwise, to make this noise?), but that the playfield didn't light up and the game didn't start. I was advised to check everything over carefully before turning it on, lest I find myself with smoke and fire.

So I've looked through the DE-specific info on the pinwiki, and checked out the following guide for things to test: techniek.flipperwinkel.nl/desega/index1.htm (not linked since I just created this account and can't add links)

The fuses test fine (and clips are solid), the transistors seem good, no obvious burns on the molex (but I need to admittedly take a closer look), and I'm slowly working through the other recommended things to check before powering it on again.

So my question is, what else should I review before I try turning this on again for the first time? It seems like troubleshooting this is really going to require powering it up to better diagnose, but I want to make sure I've covered my bases before flipping the switch. What sort of things could I test (sans power) that might cause damage if they're in a broken state?

And once powered up, is there a general plan of attack for troubleshooting? Is it kosher to disconnect everything from the power supply and then test voltages coming off the connections, then slowly re-add connections to the CPU, GI, etc? Any particularly good order to do this in? (I read up a bit on bench testing the CPU board with a PC power supply, so I was going to test that separately to see if it's working as expected.)

Most of the guides I've found seem to be geared towards troubleshooting a game you knew was previously working, but I'm starting from scratch on a dead game. I want to make sure I take the proper precautions as I troubleshoot.

Thanks in advance for any shared insight/wisdom. I'm new to pins (other than an EM I grew up with at my parents' home), but I'm an arcade collector looking to expand my skill set into a new domain.

Yes, I noticed a few were not correct and bought appropriate replacements already. A few seemed to be just slightly higher (0.5A installed in place of a 0.25A, 7A instead of a 5A, etc). The only thing I couldn't confirm was the appropriate rating for two fuses mounted to the right side of the backbox (adjacent to the four GI fuses). I haven't tried to trace what those go to yet, and they're unlabeled.

Thanks, apparently I didn't look closely enough. The playfield coil and flash lamp wiring diagram shows them wired up to the kickback and kickbig.

You nailed it. Kickback and kickbig, found it in the playfield coil and lamp wiring diagram. Thanks!

So, I have everything disconnected from the power supply except for CN1 and CN2 (CN1 seems to be AC in and labeled IT Secondary, CN2 is ground), and then CN6 (logic power) running to the MPUs CN17. I've disconnected everything else from the MPU except for CN17 (logic power).

Can someone sanity check my assumption that this is a safe way to power up and test the MPU and see if it's booting properly?

Edit: Just to add to this, I'm getting something like 4.3V on the 5V test point on the power supply, but when turning on the game with the MPU plugged into the power supply, I'm getting nothing on the MPU test points.

Apologies that the picture is not super bright. I can get a better picture this evening, but this is what I took last night. That said, the connectors looked good. No burn or anything that I could discern.

It looks like one of the chips (IC1) was replaced, presumably because C3 was leaking (but they didn't do a great job cleaning it up). I haven't put new caps in since they looked good, but if that seems to be the root cause, I can do that (not great at soldering, but given how cheap replacement power supplies are, not too worried about using it to learn on, since I could just buy a Rottendog to replace it).

Also, does anyone know what the mark is around the top left of the underside of the board? There's no caps nearby, but it looks like something leaked near the relay?..

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Haha, nice. I need to put a new cap kit on one of my arcade CRTs, so this seems like good practice (27" CRT is waaay more expensive than this PSU if I screw it up somehow). Do you have a place you'd recommend going for caps?

Thanks for the comprehensive explanation, I appreciate it. I'll take these measurements this evening.