Project TG-16 - Recap

The next phase in Project TG-16 is to "recap," or replace all the electrolytic capacitors in the system.  Electrolytic capacitors tend to go bad over time, they are one of the biggest causes of electronics failure.  If you're trying to extend the life of a system then replacing the caps is a good thing to do.  And it's fairly inexpensive given that high-quality caps cost only about 75 cents each delivered - soldering skill not included.

The TG-16 contains 16 electrolytic capacitors inside.  Here is a picture of the motherboard with all cap locations identified.

And here's a list of capacitor values for each location (for now ignore the last 4 columns):

For the replacement caps I used all Panasonic brand FC series caps.  This brand and series is regarded as being very high quality and long life.  Another benefit is most audiophiles consider Panasonic FC series caps to be the best "general purpose" caps for audio applications.  Some audio purists use different brand caps for audio applications.  But by sticking with Panasonic FC series I avoid the need to worry about audio caps versus other use.

The next step is to bust out the soldering iron and get to work.  This was relatively easy for me, but then I have a lot of experience recapping circuit boards.

One of the biggest questions is, was this worth all the effort?  Before I recapped the system I knew it worked, so why bother.  Well this system is 20+ years old, it may work now but for how much longer?  So recapping it helps to ensure a long useful life.  As it turns out, I can quantify how good/bad the existing caps are.  There are two main ways to test a capacitor - capacitance and ESR.  Capacitance is the number rating on the cap - so a 100uf capacitor should have a capacitance at or near 100.  The second method is ESR or equivalent series resistance.  This is a measure of how freely a capacitor gives up the electrical charge stored in the capacitor - the lower the ESR the better.  As it turns out, ESR is a much better way of testing caps than capacitance.  But I went ahead and tested capacitance and ESR for both the old caps coming out of the system as well as the replacement caps.  If you look at the table above, I include the capacitance of the old cap (existing uf), ESR of the old cap (existing ESR), capacitance of the new cap (new uf), and ESR of the new cap (new ESR).

In all cases the capacitance was fine, both old and new.  And in almost every instance the ESR of the new cap was significantly lower than the old cap - on average half as much.  The one exception were the 10uf/16v caps.  Much to my surprise the original caps had a lower ESR value even after 20 years.  Those must have been an excellent batch from the factory.

I didn't stop at recapping the system either.  I also have two controllers and a turbo tap which I also recapped.  These were easy - each controller and the turbo tap contained a single 10uf/35v capacitor.  The capacitance and ESR values were in line with what I saw in the system; the capacitance numbers were fine and the ESR of the new cap was about half that of the old cap.

Next we'll begin modding the system.