Original Defender cab no power. What to check first?

[IguanaStorm]

It's for a friend.  He says nothing happens when you flip the switch.  Outside of the switch, what other simple things can I check?  I've built arcade sticks but I'm no electrician.   

[Bootay]

I just started collecting cabs and my first and only one so far is 4 Player Dungeons and Dragons. I had the same problem and then discovered that the game wouldn't turn on unless the back door was shut all the way. The door was loose and wouldn't stay closed and the lock is missing so I lodged a flathead screwdriver in it to keep it closed until I can replace the locks. I am not sure if Defender is the same way but always check the easy stuff first.   

[BobA]

Check the easy items first.   Do you have AC power to the cab?   Are the fuses on the Power Supply good?   Is something disconnected or has a harness or PC board come adrift?   

After the easy stuff you can check to see if you have the proper voltages etc by using the manual and schematic of the cab.

You can find the manual and schematics at this link.

MikesArcadeManuals

[g.robert]

Defender was my first arcade and most problematic of the seven I own. If nothing lights up you are dealing with main power. There should be a fuse and two switches controlling main power input. One switch on top left for OFF / ON control and the second inside the rear door as mentioned above. That switch is a dual position.If you have the rear door off pull the switch knob out and it should maintain that position to allow power to the main game power supply. My guess is one of those switches or the fuse is blown.

If all is good check the power supply. I replaced mine years ago with a linear PS. Frequent reboots are known result of failing power supplies.

Once you are up be prepared for RAM failures which are an easy fix once you locate some stock ram to keep on hand.

The biggest problem by far are the molex connectors at each board. Do the wiggle test and replace any that seem suspect.

[Ken Layton]

The cabinet main off-on toggle switch is on the front of the cabinet underneath the coin door area (feel around for it). Then in the back of the cabinet, you remove/open the back door and there should be a white "safety" interlock power switch. The back door (when closed and locked) pushes the plunger of that switch to activate it. If either the front cabinet toggle switch or the rear door safety interlock switch are not activated, the machine will appear dead. Both switches must be on.