Defender ROM boards..all 4 leds stay illuminated

Smart Bomb

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Pic attached...Im working on my project defender...on the rom board, when i turn the game on, all 4 leds light up and stay lit...no blinking...i looked up the manual on arcade museum and i didnt see any trouble shooting for the rom leds when all 4 stay lit...they have every combination of led patters but nothing for all 4 staying on. Obviously the game isnt playing..my screen has steady horizontal lines thru it with an all white screen..the monitor and chassis are good and working.

I am getting 5 volts to main pcb and rom board...i have reseated all of the chips on rom and main pcb.

So any idea what i should look at next?
 

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The LEDs turn on on reset and are turned off at the beginning of self test.

If they don't turn off, code isn't being executed properly.

IIRC, you only need ROM3 to get going but 1-3 is safer.
 
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The LEDs turn on on reset and are turned off at the beginning of self test.

If they don't turn off, code isn't being executed properly.

IIRC, you only need ROM3 to get going but 1-3 is safer.

Are u suggesting i remove all roms except 1 thru 3 and turn the game on?
 
That'll at least eliminate the other roms causing bus contention as an issue... But sockets and the rom boards cable are likely problems too.
 
That'll at least eliminate the other roms causing bus contention as an issue... But sockets and the rom boards cable are likely problems too.

bad ribbon cables can cause 4 LEDs for sure. I think that effectively means its not talking at all right?

I'm willing to bet you get the same result with the ribbon cable unplugged if I recall.
 
any noticeable battery acid damage on the CPU board? If its not running those 4 LED's will be stuck on. Otherwise try as Hudson suggested. You could also move that ribbon cable back and forth while its powered up to see of the LED's go out. If they do that cable is probably bad.
 
That'll at least eliminate the other roms causing bus contention as an issue... But sockets and the rom boards cable are likely problems too.

I pulled all but 1, 2 & 3....still the same...all 4 leds come on and stay on.....then i pulled 1& 2...left 3 in it...same result.

And now all of the sudden my -5 led on brick isnt lighting up....pic attached is what the screen looks like with all roms...or 1,2 & 3....or just rom 3

Its a g07 that has been deluxed recapped and is a working g07.
 

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bad ribbon cables can cause 4 LEDs for sure. I think that effectively means its not talking at all right?

I'm willing to bet you get the same result with the ribbon cable unplugged if I recall.

I messed with ribbon cable....zero change..they didnt even flicker.
 
depends on the break. if it's a wire break, flexing can alter things. if the wires pulled out, that's a different story.

you can throw the kitchen sink at it and hope that works. lol
 
what about acid damage on the CPU board. Its starting to sound like the CPU isnt even running.
 
-5v

Well if your -5v is still out... then you need to sort it... as the ram on defender board needs +5, -5v & +12v. it won't run without it .... thats for sure.

Could be the processor socket... might be worth pulling out a little and pushing it back in....

And agreed ribbon cables tend to be troublesome ......

Have you checked you have all voltages actually on the board itself....

common for cracked solder joints on the pins.... so don't check the voltage at the top of the connectors as this can be mis-leading.
 
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