Ask Hackaday: Experiences With Capacitor Failure

Regular readers of Hackaday are intimately knowledgeable about old electronics, and whether it’s about that old oscilloscope sitting in the pile of other oscilloscopes, or the very rare vintage computer made in a Soviet bloc country, someone somewhere knows how to fix it. One of the biggest problems with these old electronics are capacitors. If it isn’t the battery that’s gone dead and leaked all over, it’s the caps that are either out of spec or have already exploded.

These machines can be brought back from the dead, and in recent months and years we’ve seen an uptick in the number of restomods hitting the Hackaday tip line. If you have a soldering iron and the patience to do so, any machine can be brought back from the grave.

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Adventures in Small Screen Video

[Kevin] wanted to make something using a small CRT, maybe an oscilloscope clock or something similar. He thought he scored big with a portable black and white TV that someone threw away, but it wouldn’t power on. Once opened, he thought he found the culprit—a couple of crusty, popped capacitors. [Kevin] ordered some new ones and played with the Arduino TVout code while he waited.

The caps arrived, but the little TV still wouldn’t chooch. Closer inspection revealed that someone had been there before him and ripped out some JST-connected components. Undaunted, [Kevin] went looking for a new CRT and found a vintage JVC camcorder viewfinder on the electronic bay with a 1-1/8″ screen.

At this point, he knew he wanted to display the time, date, and temperature. He figured out how the viewfinder CRT is wired, correctly assuming that the lone shielded wire is meant for composite video. It worked, but the image was backwards and off-center. No problem, just a matter of tracing out the horizontal and vertical deflection wires, swapping the horizontal ones, and nudging a few pixels in the code. Now he just has to spin a PCB, build an enclosure, and roll his own font.

[Kevin]’s CRT is pretty small, but it’s got to be easier on the eyes than the tiniest video game system.

Tutorial: replacing bad capacitors

[glytch] sent in a tutorial on replacing dying capacitors on a motherboard, and we honestly can’t think of a better subject for an introductory tutorial. There’s nothing like having your friends think you’re a wizard for bringing broken electronics back from the grave.

For the repair a dead motherboard was [glytch]’s quarry. After taking a look at the board, he found a few bulging caps that were ready to burst. After ordering a few caps with the same voltage, capacitance, and dimensions (trust us, you want the same size cap), [glytch] took an iron and desoldering braid to the board and replaced a few caps.

Sooner or later, all capacitors are going to go break down. This isn’t always a bad thing – we picked up quite a few “broken LCD monitors” in the years after the capacitor plague and repaired them with a few dollars worth of caps. A lot of the caps in our late 80s computers have been replaced, and these machines are still chugging along.