space invaders deluxe playing blind

wrongdon

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Hi all,
I have been working on this space invaders deluxe midway boardset for some time now,and i finally have it playing blind.No output to monitor or when hooked to tv.Work i have done is replaced 7 of the rams and rebuilt the power supply board.The game plays blind and has most sounds,so ill be placing an order for the LM3900's soon.Now is it strange for the board to run at 4.66 - 4.78 volts on the +5. The closer i get to 5,the ram errors start popping up,yes i have the multi kit in it.The errors seem random,ram1 a couple times,then say 7,maybe 16.So i just turn down the voltage till it is happy.If i turn it up to +5 volts,it says ram 1 ,which i have replaced 2x to be sure.
anyways,,thank you for your time.I figure i'll kick this around a bit more before i send it out or purchase a working set.
 
There's a 10uf electrolytic cap on the motherboard.....right by the power/video connector. The video signal goes through it before leaving the motherboard. If it goes bad, you'll get no video. There's actually four of these caps by the connector. Three together, and one off by itself a little....it's the one off by itself.

Edward
 
There's a 10uf electrolytic cap on the motherboard.....right by the power/video connector. The video signal goes through it before leaving the motherboard.

Edward

Thank you,for what those cost i may as well replace all 4,even though the other 3 arent in question.I hope it can be so simple,i'll have to see if i can't steal one off of something else to see.
 
Ok folks,i've replace the 4 caps along bottom edge of pcb,no change.I have access to another set of boards.
my mainboard and daughterboard = play blind
my mainboard and other daughterboard = plays fine
other motherboard and my daughterboard = plays blind.
So i guess its safe to say the problem lies on my daughterboard,any ideas.The schematics are showing the signal from maindoard going to daughterboard on pin y.I'm coming up by working my way back from the cap bu connector with U which leads nowhere.Y on the other hand isnt connected to anything just a dead pin,but on the parts side the opposite is pin 16 which goes to an MB14241 ic.
Any help will be greatly appreciated
Thank you
 
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