As I'm sure you've surmised by the title, my TAF has started resetting. It's somewhat inconsistent, but it will eventually happen. Let me start by catching you up on what I've done and checked so far, per PinWiki:

Reseated all ribbon cables to/from Power and CPU boards
Reseated all power cables with wires larger than 18ga
Checked/cleaned PDB grounded mounts
Checked continuity of all fuses
Outlet power: 119.7V (both ACs running, same circuit as a powered on/playing TZ)
TP2 voltage: 4.97V
Voltage at pin 32 on ROM: 4.94V

When the game is in attract mode, LED3 is almost consistently on, only dimming from time to time. When the game is being played, it's typically off, only lighting up when solenoid fire. The game doesn't always reset, though. Pressing both flipper buttons makes LED3 light up fairly well, but doesn't automatically make the game reset. Something else has to be going at the same time, like a kicker or the magnets.

The only thing kinda hinkey with the game right now is the power lead to the Thing scoop kicker solenoid is off and needs to be resoldered. I haven't fixed it yet because it's easy, and I wanted to tackle the hard stuff first. Could they be related? I'll admit I didn't think about power supply wiring signal integrity and its side effects. Perhaps I'll do that while I wait for responses and ideas of how to proceed.

All of this is just to make sure I'm following procedure correctly and am checking everything as I should before I test BR2 and C5, and/or start pulling the power board. I've thought about swapping it with my TZ's board to try and see if what's wrong is isolated to the board itself, but only after exhausting all other possible causes and testing everything I can.

Any help with what else to check or any tricks you can think of would be greatly appreciated!

ForceFlow - Not yet. Added to the list. Thanks!

pinball_faz - Nope. No mods here. At least, none that draw power.

Quick update:

Checked the 5V voltage regulator at Q1 from the front for tightness. I know it's not the correct way to do it, but I'm not ready to pull the board yet. It was pretty friggin' snug. While I was there, I checked Q2, the 12V regulator also on a heat sink. It was loose as a goose. As far as I know, the heat sink isn't actually hard mounted to the board, but because it's so loose, I'm thinking that the solder might be cracked there.

Also, I decided to check the test points. Everything checked out fine except for TP8, the 18V. It maxed out at 16.5V during gameplay and 15.8V during attract mode.

After doing these checks and fiddling with those voltage regulators, I played a game to see if anything changed. I hit both flippers as often as possible and during as many other solenoids firing and magnets cycling. No reset.

Very strange....

Guess I'd better do the thermistor test, too. Just to be as thorough as possible.

Strange update:

Before I did the thermistor test, I decided to resolder the connections at the Thing kicker solenoid. I completely removed all the old solder, trimmed the wires back, and soldered them back on much more cleanly than they were.

Then I turned the game back on to check for resets. Nothing. Started a game almost immediately after the bong and hit both flipper buttons simultaneously, repeatedly. Nothing. Started multiball and hit the flippers over and over during the buildup(which is where it would reset before, sometimes). Nothing. Played a few more games and hit the flippers during every mode and other solenoid firing I could think of. Nothing.

Could it be that the increased resistance of the bad solder joints at that solenoid was just enough along that wirepath to cause the resetting? There was no voltage drop from the PDB to the MPU and TP2 was just a hair under 5V, so I figured the problem was elsewhere. I guess if it starts resetting again I'll have my answer. But until then, I'll just chalk it up as fixed.

For now.

Unchanged. I'm thinking about clipping a lead onto TP2 during a game to watch the voltage drop during a double flip in the middle of the multiball buildup. That's when the 5V LED is practically solid on(I've been playing the game with the boards exposed to watch the LEDs on the PDB).

I've got a lot of plans for the power box, actually. It's an export game so there's no service outlet and I want to put the newer style leg brackets on the game. It'll be getting a major overhaul here soon enough.