Pulled MAME cab out of storage, no monitor output

[Leif]

Between moving and having a kiddo, the last two years have left little time for my cab. I pulled the pc out and left inside but the cab was in a garage (Texas) for two years without being turned on.

Now I have hauled the cabinet upstairs to a new gameroom and have put humpty dumpty back together again. Computer fires up, monitor sounds on but I'm not getting any output from the monitor. If I unplug the cable I can see some white "sparkles" on the screen but is this enough to proclaim the monitor is working and that it is the PC?

Monitor is a Nanao 29something. Pc has the gen 1 arcadevga installed. Of course I don't have an extra laptop (died today thx to nvidia) or an extra 25/31 monitor to test on.

[qrz]

anything visable on screen indicates presence of active pwr sup, HV , h/v deflection ....

with static, video input should be suspect .
 when able, check pc settings with another monitor ...