HELP: Monitor Display help request .... please

Archived from groups: rec.games.video.classic (More info?)

Maybe someone can help me. I have a Space Encounters arcade cabinet
which I am trying to revive. I have verified the motherboard PCB and
daughter board are receiving the appropriate power supply levels.

I have some new 2107 Ram replacement chips which I just received and
am trying to locate which Ram chips are bad. I am trying to do this
by setting the DIP switch settings to "RAM test" and then placing one
new Ram chip on top of each of the 16 existing non-socketed Ram chips
on the motherboard PCB. I was hoping this would tell me which Ram
chip was bad by eventually displaying the nice RAM test display on the
monitor, however, this never occurred.

I actually tried every combination of one new RAM chip piggy-backing
the exist RAM chip as well as even combo of 2 new RAM Chips
piggy-backing two existing RAM chips. No luck.

The following are pictures of what I am seeing:

1) This shows what I see when the RAM test DIP switch IS NOT on when
the cabinet is powered on.

http://unclet.arcadecontrols.com/S [...] ipOff1.jpg


2) This is what my monitor fades to every now and again while the RAM
test DIP switch IS NOT on.

http://unclet.arcadecontrols.com/S [...] ipOff2.jpg


3) This shows what I see when the RAM test DIP switch IS on when the
cabinet is powered on.

http://unclet.arcadecontrols.com/S [...] tDipOn.jpg


4) This shows what I see when the RAM test DIP switch IS on and one of
my new RAM chips is on one of the old non-socketed Ram chips on the
PCB.

http://unclet.arcadecontrols.com/S [...] NewRam.jpg



Any help with what I should do to resolve the problem as to why I can
not see a nice game image would be nice.....


QUESTIONS:

a) Are my Roms bad (based on the images ... if you can tell)?

b) Can I simply piggy-back all 16 socketed RAM chips with 16 new 2107
replacement RAM chips all at the same time?

c) Am I damaging my PCB or RAM by piggy-backing RAM chips?

Thanks
UncleT