I worked on someone's Colecovision for the last two nights. Mainly fixing ~20 traces for controller ICs. Trace damage was not done by me. I wanted to post some comments for people looking to do this type of work, and for myself, so I don't forget what a pain this stuff can be. Please note I do not normally do this type of work, but was trying to help someone out.
Make sure your repair area has the type of audio / video connection for the console being repaired. You don't want to find out the console is RF and your TV doesn't have RF (Sony PVM). In this case the Coleco had composite video.
Take a picture of the console right when you get it. This way you know who's console is whose and what shape it was in when you got it. Make sure the console works. You don't want to start fixing controller traces, and find out the console has other issues that might make fixing the traces even more confusing. In this case the power switch was (and still is) dirty, so the console needed to be turned off and on again if it didn't power on right.
Make sure they don't mail you stuff you don't need, like controllers, power supplies, etc. This will make the box lighter and you won't lose the extra stuff they mail to you. Person who mailed it to me included a pre-paid return label, this made it much easier to send the console back.
Ask about any additional mods done to the console. In this case another modder installed a pause switch that does not disconnect from the console top. Moving a circuit board around 100 different ways to fix traces only makes it harder, when you constantly need to move the console top as well. You could certainly de-install the mod, but then take a picture so you know where the wires go and make sure to test it before mailing it back.
Check power and ground first and then re-check them. I ended up doing a lot more repair work (replacing U24 and U34) as I forgot to solder pin 10 of U18, as it was buried under trace repair wires. I bet the first time I checked ground it was there and then the IC leg moved just a little bit and ground was gone. Saw 1v on that pin (much much later) and from there it was a easy fix. In the repair area I have good lighting, however seeing as how I missed one leg perhaps even better lighting would have helped or a usb digital microscope.
Take your time. I have Chip quick, Hakko 808, etc. But the safest way I found to remove suspect ICs on a Coleco was to clip the legs, remove IC body, and then heat each leg and remove with needle pliers. This method works for common 74xx type ICs, as those are easily purchased new. Then flux and solder wick the old solder out of there. Sometimes it helped to add new solder as well. For pads that kept holding solder in the hole I heated the pad with a 1N4148 diode leg pressing into the hole. I clipped the leg and now there was a good hole, as that little extra solder stuck to the diode leg. Certainly the Hakko could help there, however some of these old Colecos are really fragile and the Hakko might lift up the pad. So be very careful. When replacing IC, always use a socket. Its just so much easier if you need to replace the IC down the road. To clean up I used flux remover, tooth brush and kimtech wipes. Don't be too aggressive with the brush as the pads can come up. None did for me, but I took tons of time and went gentle.
Repair the traces on the under side of the board and don't involve the top side of the IC socket. This way the socket is still just a socket and if the owner needs to replace those ICs its easy to do.
I used 26awg Kynar (solid core) wire. It was always easier to work with the longer pieces, couple of inches and then bend it out of the way. Since many of the ICs pads were not there, I made little hooks at each end with needle pliers and it made soldering the wire to the IC socket legs much better.
I had a spare CV system board to refer too during the repair and sometimes I would practice on it before trying what I was going to do on the board I was repairing. This worked really well, but takes more time. The spare PCB was also helpful to see what connected to what (again ~20 traces just not even there), but the schematic helped even more as then you can see how the system is suppose to work, namely what parts are involved in the section you are trying to repair. This lead me back to look at U18, as I already replaced U24 and U34. I was about to compare the signals with an oscilloscope between my working and this non-working system when I found the issue.
Donkey Kong was the test cart during trace repair and final testing was with AtariMax Coleco Ultimate SD cart.
I know I'm super slow at this, but I can't see how one makes any money at doing this. So my recommendation is to stay away from repair work on older consoles.
Click on the picture for a bigger view.