Atari Edge Connector Repair

bit_slicer

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One thing I've been working on for the last few weeks is coming up with a decent method of repairing burnt edge connectors commonly found on older Atari boards. The metal on the board edge connector is often dissimilar to the metal on the leaf pins in the crimp housing on the wiring harness. When the metals are in contact over time, the two metals will corrode and develop an electrically insulating layer between them. As the insulation increases, the resistance increases and the power supply must push more and more current in order to maintain voltage. With more current comes more heat and the result is edge connectors that get burnt, charred and fall apart.

Folks (operators I guess :)) have come up with some creative ways to fix this problem, but not all of them nice and clean. :p Exhibit 1 is a Missile Command board that was violated:

mc1.jpg


Poor Missile Command! Who did this to you???? :( Don't worry, we'll fix you right up! :D
 
First step is to remove the old solder work and gently scrape away the charring. Turns out this one wasn't too bad. I've had others where the board substrate was completely compromised. Fortunately that isn't the case here.

mc2.jpg


With the charred bits scraped away we can now fill in with epoxy. The epoxy dries clear so before application I added a very small amount of colorant that hides the rest of the burnt area.

mc3.jpg
 
Epoxy added to the hollowed area, dried, and sanded down smooth and even with the board substrate. Now we're ready for the copper trace that will replace the original.

mc4.jpg
 
I found some tin-plated copper foil that is not only easy to work with but also gives a much better approximation to the original material. Cut to match the finger width, soldered on one end and a dab of epoxy on the leading edge:

mc5.jpg


Not too shabby! :D
 
The repair is structurally and electrically sound. In addition to the solder joint between the new copper and the old, the adhesive is also conductive.

I've found that the repair is just as much art as it is methodology. After a few tries I'm starting to get the 'knack' of doing this. The biggest drawback of the repair is it adds about an extra week to the repair.
 
Nice work. Don't forget to also replace the edge connector on the harness or you'll have the same trouble in no time.

It also proves Atari (and all the others) should have used a separate (Molex) connector for the power supply to the board.But hey, they weren't interested in having those games run for 25 years ;)

Must say I've been lucky, none of my PCB's developed this problem.
 
That trace isn't looking too well though.

Looks much better than it did. :D There is some discoloration from the heat, but it's still structurally ok. All of the really charred substrate and copper was replaced.
 
I am going to try to test out my Pole Position soon. Thanks for the tutorial - I may need it soon. :)
 
Thanks!

I got the foil from mouser.com:

http://www.mouser.com/ProductDetail...lty/1183/?qs=sGAEpiMZZMuHSyTciuLGf3kd9PRPR1UW

It is a bit expensive, but 18 yards of it is kind of a life-time buy.

mate this is magic work - i have been thinking about a similar process to repair my pacman boards and putting this into a tute has saved a lot of trial and error on my part!

another thread suggested this product - http://www.electronix.com/catalog/product_info.php/products_id/5771

but where did you get the tin-plated copper foil from ?
 
Just curious why you couldn't wrap the foil tape around like the first photo shows? Yes it is a little longer/deeper than the rest of the edges but there is less chance of rolling the foil back when you insert the edge connector into a tight connector. I've had a few repairs do that. Of course, I didn't have adhesive foil and instead had to glue the piece down. This would obviously only apply to those traces where the input is shared, ie 5v on most Atari boards. You obviously wouldn't want to do this to a video trace or a controller trace. Granted if you replace the edge connectors on the cabinet with new pins you should have good contact but this would doubly insure you have good power going to the board by "sharing" the power across both sides. Your epoxy idea is great. That never occurred to me. I've never thought about rebuilding that area. Don't know why. Of course, your trace is now marginally higher than the rest of them but shouldn't cause that much of a problem with the edge connector.

A second questions that needs answering is where to get replacement 44 pin etc connectors and pins for the Atari harnesses? I realize jamma harnesses are pretty much standard and Bob Roberts has a lot of the stuff needed on his site. Just thought I'd mention that for people that don't realize both parts of the connection need to be fixed.
 
Some good points here. The idea behind the repair is to get it back to as close to the original look as possible. The initial repair was certainly electrically 'good enough', but just plain fugly. True, you could wrap the foil around and have a more-decent mechanical connection. But with an epoxy cap it works just as well. The trick is to put as much on the cap as possible without getting any on top of the finger itself. Then carefully sand it back. I must admit that I went back later and re-capped the Missile Command repair. The Centipede repair represents the finished result better. It definitely won't peel back.

Another good point is replacing the harness pins if they're burnt or otherwise unrecoverable. I think someone else brought this up earlier too. If the leaf crimps in the wiring harness housing are bad, certainly replace those too. Now I've tried a few different crimp and housing products and I must warn to be careful which ones you get. Some of them are just crap. (I don't know what Bob sells.) I've found that these products work very well together:

http://www.molex.com/molex/products...CARD_CONNECTO.xml&channel=Products&Lang=en-US

http://www.molex.com/molex/products...CARD_CONNECTO.xml&channel=Products&Lang=en-US

http://www.molex.com/molex/products...IMP_TERMINALS.xml&channel=Products&Lang=en-US


Just curious why you couldn't wrap the foil tape around like the first photo shows? Yes it is a little longer/deeper than the rest of the edges but there is less chance of rolling the foil back when you insert the edge connector into a tight connector. I've had a few repairs do that. Of course, I didn't have adhesive foil and instead had to glue the piece down. This would obviously only apply to those traces where the input is shared, ie 5v on most Atari boards. You obviously wouldn't want to do this to a video trace or a controller trace. Granted if you replace the edge connectors on the cabinet with new pins you should have good contact but this would doubly insure you have good power going to the board by "sharing" the power across both sides. Your epoxy idea is great. That never occurred to me. I've never thought about rebuilding that area. Don't know why. Of course, your trace is now marginally higher than the rest of them but shouldn't cause that much of a problem with the edge connector.

A second questions that needs answering is where to get replacement 44 pin etc connectors and pins for the Atari harnesses? I realize jamma harnesses are pretty much standard and Bob Roberts has a lot of the stuff needed on his site. Just thought I'd mention that for people that don't realize both parts of the connection need to be fixed.
 
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