Monday, April 29, 2013

Reviving old equipment

Every now and then, I am handed the opportunity to breathe new life into old gear. So far this year, I have revived a Heathkit IT-28 Capacitor Checker and more recently, an EICO Model 377 Audio Signal Generator. Both are tube-based and built to last. Unfortunately, both had problems when they came into my hands.

More after the jump.

Once I got the EICO 377 opened up, it became immediately obvious that the capacitors need to be replaced. This piece of gear dates from the 1950s and the electrolytic and tubular paper capacitors of that era tend to dry out over time. This greatly reduces their capacitance and can also lead to (dramatic) failure if energized. As you can see, the large capacitor in the center of the chassis has sprung quite a leak of waxy electrolyte.

I am happy to say that a little bit of surgery with a soldering iron and some modern era capacitors of the appropriate voltage rating brought this guy back to life. I also took the liberty of replacing the power cord (non-polarized, 2 prong) with a polarized, 3-prong cord. The EICO chassis previously was floating, which strikes me as a Bad Idea. The chassis is now properly grounded. Sorry to say that I forgot to take a picture post-surgery!

The Heathkit IT-28 Capacitor checker also needed a new set of capacitors. None of them had leaked like the EICO's, but they were still in need of replacement. The Heathkit also had a couple of resistors that had swelled and cracked. Once the caps and damaged resistors were swapped out, I had another useful tool for my workshop. As a bonus, it has a cool green 'magic eye' display tube indicator! (that's the tube at the top of the chassis)

The next item on my list is a 5 MHz single-channel Heathkit Oscilloscope (Model 10-4541) that was given to me recently. If that one proves to be 'interesting', I'll do a post on it as well. ;)

Happy restoring!

~ eW

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