School me on: IC leg repair

ieure

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This is a thing I've come across a few times now. I had an Asteroids with a lifted leg on a counter IC to speed it up. Tried repairing the leg, but gave up and replaced the whole IC. I have a dead Gaplus PCB with a rusty-/missing-legged custom IC which I haven't been able to source a replacement for and haven't tried working on.

If anyone has good tips, techniques, videos, etc about fixing IC legs, I'd really like to hear about it.
 
You might want to try mounting the IC onto a suitable machine pin socket and then de-oxidizing and soldering the damaged pins to it. Sacrifice an old IC with long pins and cut them at the base if the original pins are too corroded. Keep the heat on the IC to a minimum.

I hate using this option but custom ICs don't grow on trees.
 
Sometimes it's easier to put the ic in a socket and solder a wire from the broken leg to the socket leg.
 
Liquid flux is your friend in this situation. Use it liberally to make sure everything is clean and to minimize the amount of time you spend heating up the joint. Then solder on a leg from a diode or capacitor.

If you are concerned about breaking other legs solder everything together then insert it into a socket so that new insertion/removal stresses are not on the legs of the IC. Sockets can stack easily as long as there is enough head room for the stack.
 
If the leg is broken off close to the body of the chip, use a dremel and a grinding wheel to grind down the epoxy body of the chip to expose some more leg surface to solder to. Use an EPROM that has a slightly skinny body with more leg showing as a donor to pull a replacement leg from.
 
Not ideal, but wedge a sewing push pin into the socket and have the pin make contact with whatever is left of the leg. Solder if you have enough leg to grab on to.
 
You might want to try mounting the IC onto a suitable machine pin socket and then de-oxidizing and soldering the damaged pins to it. Sacrifice an old IC with long pins and cut them at the base if the original pins are too corroded. Keep the heat on the IC to a minimum.

I hate using this option but custom ICs don't grow on trees.

This is pretty much what I do. I have tried different ways and this seems to be a good way to go. Once its in the machine pin socket you dont have to worry about the fragile legs on the custom. Although machine pin legs can be quite fragile themselves so you still have to be careful with them.
I soak the custom in tarn-x first to remove all tarnishing on the legs. Rinse in warm water then dry. At this point is should readily take solder. Place the custom in the machine pin socket and solder the legs to the MP socket. Do a couple pins at a time and give it a minute to cool down. Take your time with this, you dont want to kill the chip with heat.
I leave the broken pin(s) until last. I use an end mill on my benchtop milling machine to remove just enough plastic on the customs case to expose some leg to solder to. Insert a small solid wire into the socket, solder then solder the other end to the custom.
I think I know exactly which custom your working with. I have a pacland pcb that is otherwise fully working other than that custom. In this case all its legs are fine, the chip actually died. I had bought a couple dead gaplus boards to harvest the custom from but both boards ended up being repairable so I still need a custom. This chip was only used on a few boards, its a hard one to find.
 
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These tips are really excellent. I was worried about the insertion force to get it into the socket breaking the repaired legs right back off. Using a second socket sounds like exactly the right way to get around this.

Do a couple pins at a time and give it a minute to cool down. Take your time with this, you dont want to kill the chip with heat.
One of the things I picked up somewhere and have been doing is to alternate ends/sides of chips when applying heat to avoid damaging the IC. So I'll start at the end of one side, then do the middle of the opposite side, the opposite end of the first side, etc. Rotating the heat application around so it doesn't build up too much in any one area.

I think I know exactly which custom your working with. I have a pacland pcb that is otherwise fully working other than that custom. In this case all its legs are fine, the chip actually died. I had bought a couple dead gaplus boards to harvest the custom from but both boards ended up being repairable so I still need a custom. This chip was only used on a few boards, its a hard one to find.
Yeah, it's the 15xx one, and I think it was only on Gaplus, Mappy and Super Pac. I've been on the lookout for parts boards, but haven't turned anything up, and I'd really like this board working again.
 
Find donor IC and snip leg off.
Using needle nose pliers, gently insert donor leg into socket where it should go.
Put IC with broken leg into socket and try and line up donor leg to stub on ic.
Solder.
 
I just found this on mine. My board just stopped working one day, so last night I decided I would clean chips, look over the board good, and found this.

How does this happen anyhow. this wasn't the result of being miss handled or removed in careless manner. Are they just that freakin fragile? ImageUploadedByTapatalk1424112806.547011.jpg

ImageUploadedByTapatalk1424112826.713409.jpg

Going to attemp to repair this till I can locate a new one
 
The silver seems to oxidize until the narrow part of the pin breaks off. Just a product of being 30+ years old and being in air.

Once the silver plate is damaged the steel pins are exposed to air and just rust away.

This is why you DO NOT clean pins on these customs with sandpaper. You use Tarn-X, an eraser, or a fiberglass pencil.
 
Ya I I know there, super fragile, and I took great care removing it. But I think it was broken before hand, part of the leg remained in the socket, which I removed. Pencil and supporting the legs has Been my choice of cleaning up the legs... So I'll try tar ex to clean this guy up, some flux and see if I can fix this, report back when I get to it
 
You have to rinse off the chips with clean water when done and make sure you dry them fully or you'll end up with rust and more damage.
 
You have to rinse off the chips with clean water when done and make sure you dry them fully or you'll end up with rust and more damage.


Would any dielectric grease be useful when installing? I've never heard anybody talk about it, I use it on ECM connections that are low voltage exposed to elements in the motorcycle world, that's all 5v stuff. But there's not a lot of heat involved.
 
Would any dielectric grease be useful when installing? I've never heard anybody talk about it, I use it on ECM connections that are low voltage exposed to elements in the motorcycle world, that's all 5v stuff. But there's not a lot of heat involved.

Never tried it.
 
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