hard to tell at this point.   my pal has made it back to life !     psu shortcircuit blown : the 220v cable !,  the screen + the 5 volts +we guess  the "breakers".
it starts again. but even if it runs in tests in 4 directions !!   the game corrupts on startup and so it cannot move.  i ordered a bunch of 10 triacs from usa  (i wait..).  and i will go to electronic local shop at next holidays (i live ~2hrs distance from the arcade warehouse for our games..)   with the "5k" ohms which drive the directions.  because i cannot see what kind of model it is.   only a number "76" is labelled in it ?!
yep i printed all the scans/pdf manuals i could on the net.    i hope it comes from the triacs.   many americans on "klov" say about it,     but is it "urban legend" ?   .  ...do they really repair the game ?   as i dont see any information about the 5kohm pots  precision too .. i have some doubt
good thing to have a AB upright,  i have myself too.  i took her motherboard..  my DX was without it too..
for a long while we thought that there were 3 different motherboards (visuals were kind of non 100% match);,   for each dedicated game.  luckily  even the AB upright has the "DX" version in the tests !!  

  i salvaged already a small "5VDC part"  and the monitor i guess later,   i have too a problem with the "missiles" button,   disconnected the wires , and i was lost.. something went wrong,    i went to check the AB upright to redo it..   (nothing on internet about the connectivity,   only schematics which are terrible to read or understand)    
.. (i tried using a scaler cga to vga  with a 19" tft screen,  but colours are weird in white tones..)
so at this point i have something "BAD" about left/right test, ...  only one time it passed thru...and i could play.. but with only up/right axis movement...
if triacs change, and 5kohm pots change  dont solve the problem, i'll be stuck without understanding more i guess...

