Yes, that test ROM will show you ALL simultaneous closed switches. The default Bally switch test will only show the lowest number switch that's closed without telling you about other simultaneously closed switches.
https://www.pinwiki.com/wiki/index.php?title=File:Sco_testrom.zip

The 1800 points and bonus advance are from the other three switches on the same switch return line as the start button (lower pop bumper = 1000 points, dragons den capture ball = 500 points, "C" target = 300 points plus advance bonus).

BTW when you start a game the A, B, C, D, E, F lamps should all illuminate. You've mentioned a few times the E and F illuminate, this is normal. Have you changed the capacitors on the C and D targets, the pop bumpers and the dragons den capture ball target?

Disconnect J2 (playfield switch harness) from the MPU board. Does the start button still misbehave? this will tell you if the problem is on the playfield or not.

LostWorld_SwitchMatrix.png

If the 1800 point problem still happens with MPU J2 disconnected, the problem is NOT on the playfield.
With the game off, test the diode on the start button switch (I know you said you changed the diode but lets see if there's some short there).

So long as no part of your body is touching ground, then it's ok. Better yet, make the start button switch contacts touch each other without you making skin contact. Your body can introduce unwanted noise.

The blue circled switch is just a rebound switch that scores 50 points and advances bonus.

The cabinet/front door switches are part of the same switch matrix as the playfield. Same switch strobe and return lines. The matrix switches I marked in red are in the cabinet/front door. The 32 DIP switches on the MPU board are also a part of the switch matrix, difference is they're only read once on power-up.

There's a problem with the switch strobe #0 line (which goes to the start button) somewhere that it's shorted to something. When you hold the start button, the short is causing the software to see those other switches on the same row as active - note this is a *phantom* effect, not a physical issue with those other switches.

I've got to head out but looks like you're getting help otherwise. Good luck!

With J2 and J3 connected on the MPU board:
The start button red-yellow wire is the exact same strobe signal as the white-red wire on the playfields outhole switch for example.
The start button blue-white wire is the exact same return signal as the brown-yellow wire on the playfields "C" target switch for example.

I've updated the switch matrix diagram above in post #8 to overlay the cabinet/coin door wiring details.

So technically if you jumper the outhole switch diode (banded side after the white-red wire) to the "C" targets brown-yellow wire, this will activate the start button using the same switch matrix signals on the playfield. Try this and see if you get the 1800 points or not. If 1800 points gets added, disconnect J3 from the MPU board and try again.

You've got some corrective work to do on the coin door.

LostWorld_CoinDoor.jpg

So..
When you remove J2 from the MPU board and press the start button with available credits, the game starts and you get 1800 points.
When you disconnect J3 from the MPU board and jumper a wire from the banded side of the diode on the outhole switch to the "C" targets brown-yellow wire with available credits, the game starts and you get 1800 points.

If this is all correct, it points to a problem on your MPU board because you isolated the playfield switch harness in the first test and isolated the cabinet switch harness in the second test with the same result.

The other two switch issues you mentioned in your last post are related to the same problem with the switch strobe #0 signal being shorted.

Remove both J2 and J3 from the MPU board.
With the game OFF, multi-meter set to resistance mode, black meter lead on ground, probe each pin on the MPU J2 pin header and let us know resistance each pin reads. J2 pins 1-5 and 8-15 should all measure the same around 56k ohms.

Measuring resistance/continuity with power on will give you false readings.

Post some very clear pictures of the outhole switch from side on. Also some clear high resolution pictures of the MPU board front and back.

Then move all 32 DIP switches on the MPU board to the OFF position. Does the start button still misbehave with the 1800 points?

The pics don't fully show J2 and J1 (upper 1/3 of the board).

You got a logic probe or better an oscilloscope?
If yes, with J2 and J3 disconnected, what does it indicate on the switch strobe lines pins 1 to 5 at J2?
If no, what voltages do you measure on those pins?

Finally we have a clue..

What activity do you see at the source of switch strobe #0 which is the PA0 signal at pin 2 of U10?

My guess is you have an open circuit from U10 pin 2 to the junction of diode CR43 and resistor R31 (which is under the red S33 activity switch). This results in R31 (which is a pull-up resistor) constantly pulling strobe #0 Hi.
Having said that it should also be causing lamp issues and player display 1 issues.

Provided that J2 and J3 are disconnected, then no.
If CR43 was open circuit, J2 pin 1 would indicate Low via the pull-down 56k ohm resistor at R132.
If CR43 was short circuit, then banded side would be pulsing like the non-banded side.

Your previous 56k ohm measurement on J2 pin 1 with respect to ground did not indicate any short after the banded side of CR43.

Please confirm 100% that all measurements since post #31, connectors J2 and J3 have been disconnected?

Remeasure the banded side of CR43 but this time flex the board while doing so, especially around U10. Any change in response?

How much resistance do you measure between pins 1 and 2 of J2 and also pins 1 and 2 of J3?

There's no pics showing the back of the J3 pin header. Can you see anything amiss there?

So it was still indicating HI on the banded side of CR43?

What variety in readings were you getting? On spec you should have got a total 112k ohms via the two 56k resistors at R132 and R111.
I can't see anything in your pictures or resistance readings to show the signal from the non-banded side of CR43 onwards being shorted to anything.

With J2 and J3 still disconnected and the board powered on, how much voltage do you measure at:
J2 pin 1 =
J2 pin 2 =
J3 pin 1 =
J2 pin 2 =
CR43 banded side =
CR43 non-banded side =
J1 pin 15 =
U10 pin 2 =
U10 pin 5 =
U10 pin 40 =

Unsolder diode CR43. What does your logic probe now indicate on J2 pin 1?

Below is the MPU schematic of the switch strobe #0 signal as it comes out from U10 pin 2 (PA0) signal. Orange trace shows its travel to the non-banded side of diode CR43.
Banded side of diode CR43 onwards trace in green - as you can see there is nothing from the banded side of the diode onwards connecting it high, all connections are to ground.

MPU_Strobe0.jpg

With power OFF and J2/J3 disconnected, measure the resistance across R132 (which is for J2-1) and then R111 (which is for J2-2). Both should be about 56k ohms. When you measure across J2 pins 1 and 2, effectively you're measuring through R132 and R111 in series and should get 112k ohms total.

Check them in circuit first (again, machine OFF and J2/J3 disconnected). R133 and R60 should both measure around 1.2k ohms.

At 2.02 volts, in TTL circuits this is a very marginal HI. In CMOS circuits this is neither HI or LO. If you set your logic probe to CMOS you won't get a HI reading.

Please replace CR43 if you have a spare 1N4148 or 1N914 diode.

Yes, go for it!

The caps in the circuit are too small to have this effect. BTW if you're touching the metal ends of the multimeter probes with your fingers, your body will affect the resistance readings.

If you're replacing switch matrix diodes on Mars God of War, then 1N4148 are not suitable. See the current discussion here, particularly the second half of the thread:
https://pinside.com/pinball/forum/topic/need-help-with-system-1-game-slow-response-time-

Just above the J3 connector, unsolder one leg of resistor R59 and lift that leg from the circuit so it's not making contact. Does this make any difference to J2 pin 1 reading HI with your logic probe?

Regarding CR43, you could temporarily try replacing it with a 1N4004/1N4007 diode if you have either.

Yes, you need a diode in CR43. If the original CR43 is still there that's fine for this test.

Changing Q55 didn't make a difference? What replacement part did you use?

The lamp symptom suggests Q55 is faulty. Can you swap it with another of the large SCRs on the lamp driver board and see if the fault follows the SCR?
BTW is it a typo that the part number is really a CR 106-6R ?

Alright, this suggests some resistive short between pins 1 and 2 of the J3 connector.
With R59 lifted, pin 1 of J3 is connected to nothing. So with the machine OFF and J2/J3 disconnected, if you do a resistance measurement between J3 pin 1 and J3 pin 2, do you get any reading?

So the 'suspect' SCR now controlling the "F" target lamp, is working ok. What's happened with the Dragons Den 5k lamp now it has an original SCR driving it?

Provided your fingers weren't touching the meter probe tips, then you're reading some capacitance which you shouldn't. You should be reading nothing, i.e. open circuit.
BTW just to clarify, when I say to measure resistance across pins 1 and 2 of pin header J3, I mean one meter probe on pin 1 and the other meter probe on pin 2.

First, try cleaning the resin flux off the back of the board where pins 1 and 2 of J3 pin header are soldered. See if it makes a difference to the reading. Having said that I suspect there's something on the top side of the board under the pin header plastic between the pads that's conducting.
I know you're getting tired of this but I think we're close.

This has been a real head scratcher because there haven't really been any readings that were clearly out of spec.

Ok, fingers crossed when you solder it back in.

BTW I'm impressed how you lifted the pin header plastic

BTW2, with resistor R59 still lifted, the self test button on the coin door won't work. It won't affect anything else.

So when the pins were out and the J3-1 and J3-2 pads were clean, you got no reading.
Pins then got soldered back in and now there's capacitance again. What's the chance it's the flux/resin in your solder causing it?

If you reconnect R60, R61 and the J3 pins 1 and 2, *but* leave R59 lifted, does the start button operate properly?

When this happens, if you immediately go to switch test mode, does pressing the start button show '06' in the player displays?

Can you post some clear pictures showing the J2 and J3 connectors plugged onto the MPU board? Just wondering if someone's previously hacked the wiring on the connectors.

I slice the extra section off with a blade so the housing becomes the right length.

I don't see any issues with the J2/J3 wiring.

When this happens, if you hold the start button and wiggle the J2 and J3 connectors does it respond? How about if you wiggle the front door block connector just inside the cabinet on the left side near the tilt mechanism?

Pictures below of the outhole trough from my Playboy - yes she needs a clean

IMG_0022.jpg
IMG_0021.jpg
IMG_0023.jpg
IMG_0015.jpg
IMG_0016.jpg

Tension the upper switch leaf so it's pushing the ball wireform up.

Sorry about the poor quality pictures, if these are no good I'll try and take more after my camera battery recharges.
Note the blue electrical tape you see is me isolating the switch from the ball wireform.

IMG_0032.jpg
IMG_0025.jpg
IMG_0033.jpg

Note it's important the upper leaf has no electrical connection to the ball wireform. There should be a fish paper separator on top of the upper leaf isolating the leaf from the wireform. Long story short, the ball entering the outhole can make a connection from the switch to ground through the ball guide/apron/lockdown bar receiver if it's not isolated.

Disconnect that connector, on one side you'll see the female terminal has probably opened up. Just use a pointy tool to try and close it so it grabs the opposite male terminal better. If you notice corrosion in there, you probably need to re-terminate it.

Not an issue - actually when the ball sits on the wireform it connects it to the trough guide anyway. So long as the switch leaf is isolated from the wireform is what matters.