Need help with Defender troubleshooting..

[megamanmk2]

Hey all, I have this Defender machine I am trying to get to working order again, and the on-machine diag is less than helpful...

When the cab is powered up, it makes the little start-up sound/jingle thing, and nothing more, the monitor looks like this:



It has the 4 LED diagnosis instead of the alpha-numeric one, and on start-up all 4 leds blink twice. According to the manual this means all is ok? From what it appears the game doesn't even boot up, no Defender "growl", the start buttons don't do anything.

Some time after the 4 LEDs blink twice, I can press Advance while in Manual Down mode, supposed to do ROM tests, doing this causes the second LED to blink twice...which I don't see how it correlates to anything under the ROM test as in the manual under "ROM Failure" the first thing it says is "1st LED lights". From here I go to Auto-Up and hit Advance to do RAM test, in which LED 3 blinks twice.

I am not sure if I just don't understand how to read the LEDs, or if there is something really wrong. I checked the power supply voltages, everything plugged in for load purposes. I get about 12.5v on the 12v regulated, +/- 4.9x volts on the +/-5V, and around 14v on the 12v unregulated. I get all 3 LEDs lit on the power supply.

I have read a few websites on peoples Defender cabs, including a couple forum posts here. Was hoping someone could help me figure this out, never worked on one of these before =/

Thanks for any insight.
-Daniel

EDIT: I forgot to mention, I cleaned all the connectors and chip sockets with Caig De-Oxit, re-flowed the solder on all the Molex connectors, cleaned all the fuse holders and checked the fuses with a multimeter. Sometimes when you just randomly mess around with the buttons on the backside of the coin door, the machine sounds like it restarts, and sometimes it will make strange "bwoop" noises, in which any button press on the control panel will cause the "bwoop" to happen. Also, as I now think about it, two 3rd LED blinks is 'supposed' to mean CMOS has no fault, I might have just pressed autoup/manualdown again trying to get the LEDs to do something and entered CMOS test..not sure.

[Pinball Wizard]

Adjust the flyback on the monitor. The brightness is way to high. It could possible have something on the screen and you would never see it.

[megamanmk2]

Thanks for the tip, I turned it down, I recorded a short video of all I get:

[megamanmk2]

Checking the voltage at the actual RAM indicates 4.90v at the +5v pin, and -4.90 at the -5v pin, 12.10ish volts at the +12v pin. Checked all three banks and every other ram chip in each very carefully with my multimeter(Digital).

As far as I can tell with the "bwoop" noise I was experiencing, and successfully recreating it, I was in the sound test mode. If I leave it alone it will cycle through various sounds of shooting, hyperspace, etc. Pressing buttons during this mode causes it to make noises apparently.

Still confused at the odd LED readings though, two 2nd LED blinks for ROM test, and 2 third LED blinks for RAM test, neither of which seem to make sense according to the book. Lurking around some old posts, could it be my power supply? When on, it doesn't get 5v out the power supply board connector, but close (like 4.97). Not sure how picky these things are, the only other comparatively old wiring I have worked on is my 280ZX Turbo...and its REALLY picky.

-Daniel

EDIT: I checked continuity of all my socketed chips and found that the Decoder ROM 3's socket was porked, got a new socket from Radioshack, took the old socket out and soldered the new in, game now runs perfectly!

Problem solved!