9" XG

also. the neck board pcb isnt huge. surely it could be reverse engineered and a bunch of new pcbs could be made?

The convergence on the Barco is the biggest killer, its terrible compared to any NEC.

The CRT driver circuit (aka neckboard) is a very special design. The CRTs need (relitively) high voltage to drive them, the difference between full on and off state is about 100V in the driving signals, also we want this transition to happen very fast, at hundreds of MHz's (this is the bandwidth). This is a very-very hard task to achieve. So hard that only special breed of components could achieve this performance, with the death of CRTs these parts were also phased out since they were developed specially for CRTs. Neckboards need transistor to stand both high voltages but they are fast in operation, now you can't find any transistor meet these requirements. Now you can only find either high voltage transistors or fast ones, but not both at the same time, they are simply not produced anymore. This is why it is impossible to build new boards. Of course there are remained stocks here and there, but you can't be sure if they are original...
Many projector makers built their neckboards on so called hybrid-ics (mostly made by sanyo), the story ended similarly here too, without demand the ic production was shut down.
If we look it that way these CRT amplifiers were spectacular electronic desigs since there is no circuit which is copmarable to them.

The NEC projectors are so small because they are highly integrated, but they have just as many boards as other brands. Generally, convergence/focus/astigmatism driver boards contain amplifiers, similar circuits to hifi amplifiers, but while a hifi amplifier has a passband of 20-20kHz, these convergence amplifiers have a passband like 0-3MHz. Again these are very good electronic stuff. For a hifi amplifier you need two channels, in home theater say 7 channels. Now count with me. In a CRT projector each colour has individual convergence vertically and horizontally, has a dynamic and static focus and at least 2 amplifier for astig that is 6 amploifiers for only one colour. So in a CRT projector you have 18 high bandwidth high power amplifiers.
And this is where NEC could make the biggest size shrinking. Normally these amlpifiers could be built from discrete part like transistors and resistors. In the Electrohome projectors the discretely convergence and astigmatism amplifiers are filling the full backplane of the machine. In a NEC the convergence amplifiers would fit in your hand. They use special integrated circuits for this, in one package there are 3 amplifier channels built in. Using these integrated apmlifiers allow better heat tracking between channels resulting -> less drift, also the key part are preselected in factory, more accurate performance is possible. But there is a downside too, if one channel blows up you have to change the whole package unlike with discrete amplifiers where you may end up changing a few part and you are done. An other downside of these integrated circuits that these are also phased out. Also since these circuits are relatively small the generated heat is very concentrated on them they need good thermal contact, fortunately if these circuits kept cool they last just as long as the discrete amplifiers.