OP

Quoted from Arcane:

Some more progress: I connected the J2 and J3 connectors to the CPU board and try to see what the display have to say:

Not a lot of success. Even with J6 connected, the machine remains in SLAM mode and will not budge out of it. The corrosion around the J6 and J7 connectors is such that a lot of copper tracks are no longer working. I tried teh anti-SLAM modification but it did not change anything on the displays.
I have ordered the PI-1 and the Sound board from Pascal Janin in France. Hopefully, these will bring back some breadth of life in that machine. The original sound board is only producing a loud humming and this is not a good omen.
In the meantime, I have been working on verifying the wiring and continuity on the coin door and started looking at the back of the playfield. Here again, some fantastic hacking, all done by twisting the wires....not even soldering. I am amazed by how some people will attempt these kinds of modifications without understanding what they are doing. How can the switch matrix works, if you remove all diodes and connect all the wires together. Even a kid who has never taken any electrical classes would have done better.

This is why I prefer so much to work on a machine which has been retired from the field, instead of a pinball which has been hacked by a beginner with no knowledge.
Fortunately, the rest of the playfield seems to be in good shape and I could not see any other places where the "Mad Hacker" spent time destroying the original Gottlieb design.
I cannot wait for the Janin board to arrive.
Yves

OP

Quoted from Arcane:

Tonight, I looked at the various lights on the playfield and checked that they all lit up. Connecting a ground wire to each pin allowed me to verify that each bulb is working as it is supposed to.
I then looked at the driver board and realized that it is not original. Buck Rogers is one of the last System 1 machine having been produced and as such, it should have the Driver Board with the diodes on it. Mine does not have them and is dated 05/78 indicating a very early System 1 board. Another result of the terrible hacking and poor repairs that were done on this machine. I will most likely buy a new Rottendog driver board or some other alternatives.
Yves