On a separate historical Bally production early SS notes relevant to this thread, playfield serial numbers are not often the same as cabinet serial numbers on MANY Bally games from 1978-1984. This does not mean playfields were swapped either during their lifetime. Playfield serial numbers are NOT the identifying mark of the serial number of a pinball machine from any era.
Games such as EBD were "mix and match" base playfields based on larger production runs that went into the factory production. Playfields are not always identified in proper numerical order either. This included using playfields from earliest title runs such as original EBD playfields from 1981 (including white pop bumper caps) into the EBD Classic runs from 1984. Bally used what they had available until the run was exhausted, or additional playfields were required to be ordered by Churchill Cabinet Company (CCC). This can be determined from many different game aspects both aesthetically (inserts and ink screen colors), electronically (sockets and boards), and mechanically (assemblies) from parts. All three EBD models for example have many specific differences, even the assemblies are slightly unique based on minor updates.
Hence, the differences including the Solenoid Expander Board (SEB) and even its physical location.
IMPORTANT TECHNICAL NOTE:
DO NOT USE a LED in the SEB lamp, as this will not work in the circuit theory based on necessary voltage unless the circuit has been adjusted with resistance based on a standard Ohm's Law calculation. A lot of new owners do not seem to understand the SEB design technology and why/how it was used. Read the base schematics closely. The SEB lamp is part of lamp matrix, not the SDB, and does not draw power from this part of the game. The proper 6.5v from the SEB lamp is extremely important in order to draw enough current to the MOC3011 opto-isolator on the SEB and activate. I have already seen young technicians not understand these aspects and make this mistake repeatedly on this series of games.
The SEB lamp is not "just another feature lamp".
