Monitor problem Wells Gardner 19k7613

I recently bought 2 Single Monitor Nintendo Playchoices, one is
completely functional, the other seems to have a problem with the
monitor. When the machine is powered on I can hear whats sounds like
the monitor powering up (the static noise), however there is nothing
displayed. I know this machine has been broken for a very long time
(since 1992), Included with my Playchoices was a brand new power supply
and a new motherboard, I've swapped both out so I know neither are the
problem. I've also checked the fuse on the chasis and that is also
fine. I have good soldering skills and have already made sure that I
know how to properly discharge the monitor. Are there any suggestions
on things I could do to troubleshoot the failed component(s)? Thanks
in advance.

Derek

PS I'm also considering selling the extra motherboard and power supply
if anyone is interested. This way if it's something I feel I can't take
care of myself then I can pay to have my local repair shop fix the
problem.