Bent IC Pins (Legs) Last Updated on: 6/19/2013

Techie info: how to repair bent and broken legs on computer chips

Old computers and other electronic devices are usually full of the DIP (Dual Inline Package) style of chips, or Integrated Circuits. Sooner or later you'll run across some with their little legs or pins bent in ways they should not be. Here are some tips on safely straightening them back out.

First off, do what you can to prevent damage done by static electricity. Buy an anti-static wrist-strap and learn how to use it, if you're going to be doing much work around CMOS chips. (They are very sensitive to even very low levels of static electricity.) If you are brave, you can just try to hold the chips on the plastic or ceramic body parts, instead of by the legs. It can't hurt to do both.

A small hand tool exists, usually called an "IC pin straightener" or something close to that. I only use them once in a long while now, but I used them more often years ago. (Radio Shack used to carry them in their stores, but now only sells them as a "special order" item, I'm told under part number: RSU 10524502. Other places likely have something similar, but you'll have to shop around on your own to find them.)

These tools may or may not have a screw built in, that is meant to connect to an anti-static ground point. Basically, these tools are just a few simple blocks of plastic. You insert a chip loosely into the middle portion, then squeeze two spring-loaded walls inward, towards the chip's legs. The two rows of legs get crushed flat, between the various parts.

Problem is, this tool is made for newly-produced chips, more than ones that have been accidentally bent while working on them. Most DIP-style chips come from the factory with their little legs pushed slightly outward, like an awkward calf. Good luck, if you don't know this and you try to fit the IC into a board or a socket "as is"? Until you straighten the legs out, so that they are at a ninety degree angle to the body, you'll likely be frustrated and may end up with a real need to know how to straighten badly bent legs.

However, if the legs are bent too badly, the chip won't fit into the center section of this type of tool. And it only fixes legs that are bent outwards; you have to straighten them by hand, if they are bent along the long axis of the chip, which sort of defeats the purpose of even having such a device. I would say that they can be handy to have, mostly if you are afraid you'll damage the chip by straightening it by hand. Once you've gained some confidence in using other tools, you'll probably find less and less use for it?

What I use most often nowadays to straighten out bent chip legs, is a standard pair of needle-nosed pliers. As long as the tip is small enough to -- gently! -- grab one leg, while staying out of the way of the ones nearby, it should work fine. (You may also find that a favorite pair of tweezers works for you?)

Take your pliers, and carefully bend the most badly bent pins into a ballpark or approximate position, as your first step. Move slowly and very gently. Keep in mind that any thin piece of metal, bent back and forth enough times, will snap off. Its called metal fatigue. You want to avoid it as much as possible.

Once most of the pins are somewhat close to being straight, I usually pick one direction, and fix that first, then go back a second time and fix them in the other direction. Doing this gives me a fairly good view of what straight actually is, from one pin to the next. In other words, I'll hold a chip flat horizontally, looking at its side, with one row of pins facing me from left to right. I'll get those pins fixed first, so that they are straight up-and-down when compared to one another and the body of the chip itself.

I will then look at the either end of the chip to see if any pins are sticking inwards, badly. If they are, I bent them back outwards, slightly. If I have a row of legs that wanders all over the place, in both directions, what I'll do is to bend the inward ones all outward, to match the bow- legged ones. For now, this just keeps them even with one another, not necessarily at a ninety-degree angle to the body.

As a final step, I'll place one row of legs on a flat table or other solid surface, so that the body of the chip is sticking up vertically. (Think of a truck lying on its side, if that helps?) Gently roll the chip's body away from you, so that the legs are bent flat and even with one another. It is better to do it a few times, a few degrees at a time, then to keep over- bending and unbending them, making them brittle in the process.

Practice these steps a few times with some spare parts, if it sounds difficult. It isn't, once you've done it.

REPAIRING BROKEN LEGS

If you've gone and snapped a leg off, repairing it may be harder but still do-able, with some practice and the right tools. Take a close look at any random chip you have laying around. You'll see that the part of the leg that goes into a socket, is thin and wire-like. The upper portion of the leg is approximately three times as thick, when looking at it from the side. If both the upper and lower leg halves are gone, sorry, you need to buy yourself a new chip. If you snapped just the lower part of a leg off, try this to fix it. (You may even want to intentionally snap some legs off of a cheap but working socketed chip, just to practice?)

Carefully clean the upper part of the leg. Remove any obvious solder or other debris, then use grade "0000" steel wool to get a bright, shiny surface. (A rubber pencil eraser works, too, but not as well.) You can find this steel wool in better hardware stores, most likely for polishing expensive woods, believe it or not. One five dollar pack should last for years, and is great for cleaning card edge connectors, too.

Anyway, you should now have a clean, upper leg half. Get a short section of wire; an inch will do fine. A section of the wire leads from a cheap resistor, capacitor or other small spare part works great.

Soldering is beyond the scope of this article, but what you want to do is to "tin" both of these parts. What that means is that using a low-wattage (15 watts is fine, 30 is maximum) soldering iron, you heat one part up at a time, then add a tiny bit of solder to it. It helps if you use the smallest diameter wire solder you can find; you'll have much better control over how much solder gets applied, and where it gets applied. Never use acid cord solders! Radio Shack (and many other places) sells all you'll need for simple soldering. I really like their small 1.5 ounce spools of "silver bearing solder," and know they sell a decent 15 watt iron. They also have a very good desoldering iron (40 watts?) at a good price (around $10) with its own little red bulb and a hollow heating tip, but that's another story altogether. As long as I'm rambling, for most small electronics work, a "third hand" type holder will probably save your sanity to some degree, too.

Now that you have two clean surfaces, with just a tiny bit of solder on each of them, you can touch them together, hold them steady that way, and gently heat both parts. The solder on both of them should run together, and make the two parts stick together. Don't move the parts around; let it cool without any movement at all, or the joint will be extremely weak, or even electrically unworkable. And for this use, it helps if you leave the wire extra long in both directions, so you can hang onto it. Solder it on, hold it still, let it cool, then trim the new leg to its final size. When I'm doing it, I hold the length of wire in one hand with a pair of needle-nosed pliers, I hold the soldering iron with my other hand, and the chip itself is laying on its side, clipped into one of those nifty "third-hand" holders.

SOME OTHER THOUGHTS

One other, sort of related tip... once in a long while you may find a situation where you're putting a chip into a socket or set of holes that it wasn't really made for. (Replacement EPROM's, for example. Trust me on this, for now.) Maybe most of the pins are correct, but one or two aren't. What you can do is to bend the offending pins so that they are straight out from the body of the chip; like wings on an airplane, more or less. That particular pin won't go into its socket hole, but the other pins will. Attach a small length of wire to that bent-on-purpose pin, and then attach the other end of the wire to where it should really end up. I find that a wire-wrapping tool set helps out, in situations like this. But again, that's another story.

This is an even stranger, admittedly much less common situation: if you ever have a chip that you're inserting into a circuit, from scratch, it may help to bend certain pins straight out, then tie those bent pins all together with one long length of wire. ("Huh?," you probably said.) I'm thinking of one situation where an inverter (7404 chip) is being put into something like the Atari 2600 console, to make an "active high" chip select signal from the machine activate an "active low" enable line on a modern EPROM. Most guys just run four wires; power, ground, signal input and signal output. But on most gate chips -- especially on CMOS chips -- any unused inputs are supposed to always be tied either to power or ground, so that the lines aren't "floating". If they are left floating, the circuits act erratically or sometimes just don't work at all. And they may use more power than they should, as well. In the situation mentioned, all the inverter's input lines could be bent upwards, ground could be bent upwards also, and they could all be tied together with one wire and a minimum of fuss.

And here you probably thought that the only time it was necessary to straighten IC legs out, was when you bought large quantities of cheap, used-and-abused EPROM chips in bulk? Shame on you! :-)

I hope this info helps some of you keep these older machines up and running!? Good luck....

Ward Shrake

e-mail: mailto:ward.shrake@worldnet.att.net

VIC-20 web site: http://classicgaming.com/vic20/

Emerson Arcadia: http://classicgaming.com/arcadia/

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