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You are here: Experts > Shopping > Video Games > Video Game Repair > Defender not coming on fully
Expert: Octane
Date: 10/5/2008
Subject: Defender not coming on fully
Question
I played it one day and it was fine. The next day I went to turn it on and the sound started and then the upper "Defender" light bulb came on, but then the sound stopped and the screen did not initialize. Pretty much the only thing that goes to full power is the light at the top of the game. I changed the batteries ( but those are just for saved game scores right?). Is the problem one of the fuses close to the screen?
Answer
Gday David,
Your theory with the battery is sound. They are used for highest score and saving machine settings. So I would not worry too much about it at the moment.
Your starting point is the power supply, at the bottom of the machine. If it does not light up those 3 LED your are in a world of hurt. Those 3 LED represent the 3 different voltages the machine needs to work. Power supply is usually the biggest pain in the butt in the Defender machine. If one of them is not lighting up that means you are missing one of the voltages and thus the machine will not work.
I would first do a couple of things. (I would also think about investing in a multimeter and a solder iron because you will need these as a minimum.
Download a manual which can be found at http://www.robotron-2084.co.uk/manualsdefender.html which helps 10 fold and has a good trouble shooting guide. (even if you only have a simple knowledge of electronics this will help.)
Secondly (with the machine turned off) Disconnect and reconnect every molex plug you see coming off any PCB circuit board. (Sometimes even this helps) Occasionally something will jar loose when you move the machine. Start with the power supply at the bottom and work your way up.
Thirdly check all fuses on the Power supply. One of them may have blown which is a really simple fix. It has a 5 fuses.
F1 = 1A slow-blow
F2 = 5A slow-blow
F3 = 4A slow-blow
F4 = 7A slow-blow
F5 = 7A slow-blow
Make sure they are okay and they are the correct fuse.
Fourth you might want to take out the power supply PCB and check the back side of the board occasionally the pins for the connectors need to have solder flowed over them again. Check for obvious burn or short outs which may point to why it is failing. Or anything that looks like it is blown or burst. (It has a number of capacitors I would check them for bulging or being popped and a bridge rectifier, the big square thing, that burn up. You can buy rebuild kits to fix up your power supply as good as new.)
From there it is a little harder as you would then have to check voltages on the power supply in various places to see if it is outputting them correctly.
Here is another good reference page in regards to power.
http://www.coinop.org/repair/PS_Williams.aspx
Again once you get the power working properly you can move on from there, again this is the biggest problem on Defender machines. (After that monitors are the next biggest pain).
The monitor should give off a humming noise when on which should be a dead give away if it has power or not. (You can also feel the static it gives off on the front screen.) Also in a totally dark room you might be able to see either the monitor giving off a faint glow or in the back see a light in the neck of the tube indicating you have power.)
When in doubt you can always turn the contrast up to full and see a white rather than black screen. Or any one of the color plate adustments will give off a color to the screen regardless if the board works or not. If the monitor has power and is functioning you can see something on the screen regardless if the rest of the machine is dead or not.
The Defender machine runs a diagnostic when powered on. It will usually give some sort of error code on the monitor which can be checked. If it does not make the normal sounds when powered up it would be the power supply or main PCB board rther than the monitor. If it makes all the right sounds when powered up but does display anything on the scren I would surspect the screen is your problem.
I hope this helps.
Octane
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