Custom chips...post pics of repaired chips

Riptor

Well-known member
Joined
Jul 10, 2007
Messages
12,078
Reaction score
144
Location
Leonartown, Maryland
Anyone who has worked on midway boards such as Galaga, super pac, some atari boards, etc have run across this problem. The custom chips used had legs that were silver plated and become brittle over the years. Its my guess that the chemicals used in the plating process is what leads to the corrosion. At some point they realized the issue and began tin plating the legs. The chips with tin plated legs are usually in great shape after all these years.
It wasn't just custom chips that had this issue, pretty much anything Texas instruments made during the time suffer from what is now refereed to as "rot leg". Striving to preserve these classic games some guys such as James (JROK) have produced modern replacements for some of the customs. This is great but what about the ones that are not available?
There are many methods to repair these chips. Post how you fix them and provide some pictures if possible. I have fixed them different ways over the years and im still trying to refine the process. Im working on a new method right now and will post some pics as soon as I get it finished.
 
I don't have any pics of repaired chips.

I've done things such as mounting them in additional sockets, soldering replacement legs onto the existing leg, and dremeling the body of the chip to solder a leg to the hidden part of the leg when the old one broke off at the body.

I've also dremeled the body of surface mount ROMs and used kynar wire to fix issues with legs that were physically broken off. That was a repair I did to a Strikers 1945 game that took a beating.

RJ
 
Wish I had a photo... here is what I did... worked like a champ!

1. Break off all the legs leaving a small stump
2. File / Clean each stump
3. Glue/Epoxy the body to a dip socket of same size (use machined pin socket)
4. Insert solid wire into the pin of the socket and place against the stump
5. Solder the wire into the socket and onto the stump, clip excess wire off.
6. Coat the whole thing in epoxy after you test it.
 
Last edited:
It really depends on how damaged the chip is. If it's only one or two legs and the rest look fine, I'll file the stump of the damaged leg and solder on a clipped-off pin from another chip, or a resistor leg or something. Usually, however, if one leg is broken the rest aren't far behind, so I simply clean the corrosion off (a quick dip in Tarn-X does wonders, followed by a rinse in isopropyl alcohol). Tin all the remaining legs, then insert the chip into a machine pin socket and solder the remaining legs into the socket. For the broken legs, use a bit of solid wire/resistor leg/clipped chip pin and solder it to the stump and to the socket. For legs broken off completely flush, chip or dremel away at the plastic body of the chip to expose enough metal to solder to.

-Ian
 
I've built a Namco custom sound chip out of perf board once to fix a mappy... heh.

Pretty cool, how many TTL's did it require?

Im working on a galaga board that EVERY custom has leg rot. Its the worst one I have seen. I have replacements for most of them but a couple need repair.
 
Here are a few pics of one I just finished.
I break off the rest of the legs then mill part of the plastic case away. Then the chip gets soldered to some header strips. I have done a few this way and its working good.
 
Last edited:
Good topic Mike and that is some clean repair work....I have a Dig Dug board that I suspect has one or two legs with rot...but haven't tracked them down...real pain since a lot of the customs had to be cleaned..but surprisingly the legs weren't too brittle which is making it harder to find the problem chip(s).
 
Here are a few pics of one I just finished.
I break off the rest of the legs then mill part of the plastic case away. Then the chip gets soldered to some header strips. I have done a few this way and its working good.

That is an AWESOME repair!!! im impressed that looks great
 
Anyone who has worked on midway boards such as Galaga, super pac, some atari boards, etc have run across this problem. The custom chips used had legs that were silver plated and become brittle over the years. Its my guess that the chemicals used in the plating process is what leads to the corrosion. At some point they realized the issue and began tin plating the legs. The chips with tin plated legs are usually in great shape after all these years.
It wasn't just custom chips that had this issue, pretty much anything Texas instruments made during the time suffer from what is now refereed to as "rot leg". Striving to preserve these classic games some guys such as James (JROK) have produced modern replacements for some of the customs. This is great but what about the ones that are not available?
There are many methods to repair these chips. Post how you fix them and provide some pictures if possible. I have fixed them different ways over the years and im still trying to refine the process. Im working on a new method right now and will post some pics as soon as I get it finished.

I'm working on two DD boards that have this problem. I just replaced all the old crappy 28 pin sockets on one board and if the leg fell off one of the customs, I put them in sockets. Then I use a piece of solid wire (like from the end of a CAP) in the socket where the pin normally goes, then solder that to the broken leg.

You can take a look at this picture (although it's hard to see):

http://www.arcaderestoration.com/graphics/digdug/digdugboard.jpg

The Custom in the upper left is in a socket, and the 4th pin from the right has been soldered in place.
 
Back
Top Bottom