Finally got the two "missing" spotlights added to my game
Lots of thanks to wayout440 for the pointers that made me realize what I had to do (basically understand the lamp matrix lol).
I will add a detailed description of the process below as I've come to understand that several other people also want to know how to do it.
* 2 #555 wedge socket lamps with reflector - https://www.marcospecialties.com/pinball-parts/077-5026-XX
* 2 hex posts m-f 8-32 x 1.50" zinc 1/4" - https://www.marcospecialties.com/pinball-parts/02-5295-24
Slightly longer posts should work too, my spots are located quite a bit away from the cover glass.
* 2 Diodes 1N4004
* 2 pair of Molex connectors (2 circuit, mini-fit) small enough so they can fit through the hole in the PF behind the slingshots.
Don't forget the accompanying crimping terminals (male and female)
* Shrink tubing
* Zip ties
Tools used (apart from the obvious ones):
* Crimping tool for crimping the Molex terminals. It's much easier to crimp the wire to the terminals rather than soldering.
* Fiberglass scratch brush pen. Great for easily removal of the isolating lacquer above the PCB copper lines.
The assembled wires:
Diode orientation is crucial, double check this. The diode side with a line on it should be closest to the end of the wire. My initial thought was to crimp over the diode too but then it would be hard to show it's orientation so I decided not to. You should probably do it though.
There are several alternatives where to solder the two column wires (one for left and one for the right spotlight).
* "Splicing" into two of the cables (yellow-brown, yellow-red) going to the PCB and make a connection there.
* Soldering to one of the diode legs (on the PCB lamp plug side). This has the downside of the additional spotlight stop working if the PCB mounted lamp in serial before it goes out.
* Soldering directly beside one of the correct PCB lamp plugs. I'm not sure it will be proper clearance to be able to turn the lamp plug and change bulb after that so I scrapped the idea. Maybe it works...
* Solder directly on the PCB copper line. I decided to use this solution.
I used a fiberglass scratch pen to easily remove the lacquer layer and get to the copper line. If you don't remove the lacquer first then you can't solder properly and only risk on lifting/breaking the PCB trace, thus ruining it. The two red circles show the spots where I used the brush to get to clean copper.
Upper red circle is for the left spotlight and lower-right circle is for the right spotlight.
Tin both cable ends and PCB copper line before soldering, it makes the process easier.
You can connect your two cables along any part of those two copper lines that I marked.
Solder both lamp wires having a diode at the end to the left martian eye (located directly below the flipper coils).
NOTE: Make sure to solder them to the correct side of the existing diode for the lamp! Solder both wires closest to the diode side with the line.
Overview of the finished soldering; Two yellow cables (for each lamp matrix column) going to each lamp. The returning red cables from both lamps goes through a diode and to the same connection (the lamp matrix row) on the left martian eye lamp.
I also added a few zip ties to keep the new cables tidy and in place. My initial thought was to fasten the upper yellow wire to the nearby kicker assembly (using a zip tie) too, but realized that kicker vibrations might make the solder connection to break so I skipped that. Maybe I'm overthinking things...
Pinball turned on. Both spots working, illuminating the PF. The left spotlight have a normal 555 bulb in it, thus the yellow light. The right spotlight have a cold white LED as seen by the more blue-ish colored alien. Decided to go with the normal 555 bulbs as I like the green alien color and classic light bulbs are more close to the rest of the game for me.
Spotlight in action; same as above, furthest away with 555 bulb, closest one with white LED.
All in all this was a fun project and I learned more about pinball; mission accomplished!