Sometimes you partially restore something, then completely forget about it...
Or maybe that’s just me. :)
I recently got a new ‘like’ on an old post about this Eico 950b capacitor checker. I’d purchased it as part of a pair of Eico devices (the other was the RF generator I restored) from a flea market back in the ancient days.
I scrolled through the photos of the restoration, but I didn’t remember working on it or where it had ended up in my shop. This prompted an investigation. Turns out it had landed in my Cabinet of Mystery, which is a cupboard under my workbench where pieces of old technology just seem to appear from nowhere.
According to the old post, I’d replaced all of the old paper caps, but had stopped because I didn’t have an appropriate electrolytic capacitor (big red cylinder in the 3rd and 4th pics). The electrolytic is 8 microfarad at 525V. I found a 10 microfarad online, but it’s only 500 volts, and the schematic says there’s 520 volts across the cap.
So I did some research and decided to throw a few capacitors in series to create a ‘single’ capacitor of around 8mf at 550 volts. Found the right caps in my drawers of parts, but in my reading it was suggested that to make sure each capacitor charges evenly, you add resistors in parallel with each cap.
This basically acts like a voltage divider and helps ensure that the capacitors are both charged similarly. So I replaced a single component with 2 capacitors and 3 resistors. Not exactly making things simpler...
I cleaned up the faceplate, plugged it in, did a quick calibration and it seems to be working great! I’ve put it on my bench now, and look forward to using it whenever I need to check capacitors.
Stay tuned for something else!
