Task: Purchase a Desoldering Iron for Removing Bad Chips from Atari 8-Bit Computer Circuit Boards
Needed: Desoldering Iron, Circuit Board, Hot Air Rework Station
Time: 30-60 minutes
Introduction
Repairing Atari 8-Bit Computers inevitably requires removing and replacing bad chips. Some 800XLs, such as those made in Hong Kong (check label on bottom), have all the main integrated circuits including the 6502, ANTIC, GTIA, POKEY, RAM, and logic chips in sockets which makes them easy to remove with an inexpensive chip-lifter tool. The new chip can then be easily inserted into the socket with some deoxit or other contact cleaner to remove any oxidation to improve contact.
Unfortunately, there are plenty of Atari 8-bits that are not socketed requiring the bad or suspect chips to be desoldered from the circuit board. Desoldering requires some patience, a little practice, and some special equipment to complete without damaging the circuit board. I recently purchased my first desoldering iron, a Hakko FR-301, and it works beautifully. I am so happy to be able fix non-socketed circuit boards and will post later about a few 800XL I was able to easily fix. Note that a hot air rework station (i.e. a hot air gun) is required to safely get chips off the board once they have been desoldered. This is because there is often some residual solder on the pins that hold them to the board. Lifting them in this state can cause damage to the part of the board they are attached to. I will cover that in a separate post.
Instructions
Step one is to purchase a desoldering iron. I got the Hakko FR-301 from Micro Center for about $330. You should be able to get one of these from Amazon for $300 or less. I purchased this because a number of retrocomputing folks who do repairs use it and the online reviews are quite good.
Step two is to watch some online videos for best practices. Here is one I like from Adrian’s Digital Basement. This is the technique I have used successfully and recommend here. It covers both desoldering and lifting the chips off the board using hot air to melt any residual solder.
Step three is to give it a try! Be sure and use the hot air method to lift the chips out once they are desoldered. I cover that in a separate post.
Step four is to clean the desoldering iron regularly as noted in the instructions. The solder needs to be removed often from the chamber. There is also a filter there that needs to be replaced periodically. My desoldering gun also came with a long thin stick that is inserted down the gun barrel for cleaning solder and flux out to keep it working properly. There are several how-to videos to watch.
Comments
It takes at least a $400 investment to do this right including the desoldering gun and a hot air rework station. However, it is well worth the pain and suffering that comes from damaging a beautiful Atari circuit board. So happy I made this investment and now have this skill.
Once the chips are out it is a really good idea to install sockets to make it much easier to troubleshoot the next time around. You have to do the soldering anyway. I have previously posted about the soldering station I purchased and will do a future post about sockets.
You may need some solder wick to clean up any extra solder left in the holes once the chips are out. Remember not to heat too long or press too hard as it is easy to damage the board. Another approach is to add some fresh solder to the hole from the bottom of the board and then desolder again. This might be safer. You can also use a small pick to clean up the hole.
Some 99% isopropyl alcohol or acetone can be used to clean up any flux around the holes. This might be necessary if a repair job was done previously, or you want to clean up your own soldering work. 99% IPA is hard to find in stores. I purchased this one on Amazon along with a small spray bottle.