Defender: worked great for a week, now dead!!!

dazras

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Hi! I just fufilled a childhood dream by buying a Defender machine from a guy at work. I've had it for a week and it worked perfectly, although we didn't play for more than a few minutes each time, then would turn the machine off (we're not very good at it yet). My kids had a snow day yesterday, and they played it with their friends for a couple hours straight. They left it on when they were done, and about an hour later the screen was black and the buttons didn't respond. So I'm assuming something overheated since it was the longest we've had it on. I turned it off and back on, and the screen flashed white for a split second and went black again. No game sounds, but I do get the click and the coin door lights come on.

I got inside and the +5V LED wasn't lit. All fuses were ok. I removed the 3 connectors on the PSB - no burned connections or pins. I removed the PSB and didn't see any bad solders or burn marks.

I put the PSB back and plugged in the connector from the transformer only. Now all 3 LEDs are on and the voltages on the 4J2 are:

1 -4.9
3 12.1
4 -14.6
5 5.6
6 5.6
12 5
13 5
14 5
15 5

I put on the 4J3 and 4J2 back on and redid the voltages:

1 -4.9
3 12
4 -14.3
5 1.6
6 1.6
12 0.9
13 0.9
14 0.9
15 0.9

And the +5V LED is out again...
Is this a power supply issue or do I have an issue further downstream? How do I go about troubleshooting now?

Any help is greatly appreciated! Thanks!
 
Try removing the fuse's and clean up the holders they're in. I know that on my machine the fuse holders were corroded and it would not allow the +5 to work. I cleaned them up and no problems since. You must get the power supply working correctly before doing anything else. The power supplies in Defender are probably the easiest to rebuild. All the parts are easy to find with the exception the that huge cap that's on it. Be sure to also replace the 2 IC voltage regulators. When you get that done, check power at the corners of a ram chip. If you don't have the manuals you can get them here...

http://www.robotron-2084.co.uk/manualsdefender.html

...determine which boards you have (early or late) and grab those manuals.
 
I agree with Sirius' recommendation, and add the following:

When you removed and replaced the connector, a voltage drop was evident in your messages. I'd suggest cleaning those pins and sockets as best you can with a nail file or emery cloth, and see if you can't get that cleared up.

Voltage drops cause heat, which cause more voltage issues, connector overheating and damage.

Also, check the solder joints on the connector under those pins. If they overheated, you could have cracked the solder joints, which could be causing problems when you remove / reseat the connector, by causing the board and pin to shift.
 
Try removing the fuse's and clean up the holders they're in. I know that on my machine the fuse holders were corroded and it would not allow the +5 to work. I cleaned them up and no problems since. You must get the power supply working correctly before doing anything else. The power supplies in Defender are probably the easiest to rebuild. All the parts are easy to find with the exception the that huge cap that's on it. Be sure to also replace the 2 IC voltage regulators. When you get that done, check power at the corners of a ram chip. If you don't have the manuals you can get them here...

http://www.robotron-2084.co.uk/manualsdefender.html

...determine which boards you have (early or late) and grab those manuals.

+1 on everything, except that the big caps are available at Great Plains Electronics (www.greatplainselectronics.com). Ed is a great guy to deal with. He is also a member here as GPE.

ken
 
When I removed the fuses, the cap fell off the end of F1, so I bought new fuses, ran emory cloth along the fuse holders and the pins. All the pins are tight and the solder looks good. I used the multi-meter to make sure I had connectivity where I needed to. Put it all back together, checked all the voltages and now everything works again.

Thanks, everyone! Since I'm new to working on these machines, I'm sure I'll have more questions in the future. I appreciate the help!

The next adventure will be to do a cap kit for the video (I have a WG K4600 monitor)... There's a slight curl to the left on the top of the radar rectangle...

Doug
 
A cap kit never hurts, but you may get rid of the curl by adjusting the monitor. On the vertical card there is a small can type adjustment. Using a plastic screw driver you may have enough adjustment to get rid of the curl. Even after capping my monitor I had to make an adjustment on that pot. Try that before the cap kit. If that's not enough then do the cap kit, or if your feeling froggy do it anyway.
 

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Continuing the saga... I was getting a shaky picture after playing for a while so I was poking around inside trying to find something loose causing the video to shake and I got a spark when moving a purple wire. It started smoking from the board where the wire was attached so I unplugged the mahcine. The purple wire is attached in 3 places with the middle part going through the bottom board (where it was smoking). The wire was loose and I pulled it out of the board. I'm planning on removing the video boards so I can see what's going on the other side, I'm assuming I have to solder the wire back? Is this a usual failure? Picture attached...

Thanks. Always an adventure with this machine! Somewhat frustrating, but I'm glad I'm learning about how they work!
 

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Hey there...

You do know that there's High Voltage running thru live monitors right? ...and a monitor that is turned off still can hold stored High Voltage like a capacitor...
You can get a shock that will knock you on your ass - no exaggeration!
Listen, before you start messing with monitors, get a discharge tool from Bob Roberts and discharge it.

Now, if you saw smoke... the damage may have already occured.
You can try and resolder the wire from the backside, which means you will need to remove the chassis. To do that, you will need to Discharge the monitor!

If you are planning to adjust live monitors, get a set of plastic/nylon monitor adjustment tools.

Keep us posted!
Be safe!
 
Might as well get the cap kit from Bob as well. Messing around with live monitors is not something even experienced people do, count yourself lucky... Shaky picture is probably due to dried out caps and cracked solder joints on the pin headers.

Take some pictures, download the manual for your monitor and examine it. Find information on the web on performing a cap kit and get to it. Trace the wire back to the source and also where it goes into the board. Expect to find some parts that may be missing the magic smoke.

Looks like a WG K4600 with the two riser boards... First one I did was one of those; pretty easy, just follow the instructions and take your time.

Kirk S.
 
Thanks for the electrical heads-up. I will be careful and get a monitor dischare tool and plastic tools.

Because of the potential damage that already occured (smoke) and the fact that I need to do a cap kit, plus it looks like the previous owner did some ad-lib wiring, and the boards are filthy, I decided to buy a reworked video board set online and I'll just install that.

Thanks again for the words of wisdom!
Doug
 
I installed the set of reworked boards, but now I've got no picture at all.

There is one difference between the hardware I bought and what I had: On the old one, I had an extra adjustment knob mounted on its own to the metal rail to the right of all the boards. It has 2 wires, one goes to the main horizontal board (this is the one that sparked and smoked and one goes to where the horizontal coil attaches. Any clues what I could check to diagnose the problem?

Thanks!
Doug
 
F601 was blown. I replaced with a quick disconnect fuse holder and now everything looks great!

Thanks!
 
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