A few months ago (ok, maybe years), I scored a free TV off a Facebook neighborhood group. It’s a Samsung 40″ LCD. Not very new, but hey free is free. The giver warned me that it “needed a new power cord,” or so they said. I was puzzled, but then took this as their own fumbling way of troubleshooting a problem they didn’t fully understand. I figured it was worth a try.
The TV has worked for quite a while now, but sure enough — it has an issue. To be exact, about 3 times out of 10, it has trouble turning on. Its power supply sometimes failed to fire a relay, which apparently powered up the LCD backlight. As a result, the relay would shut back off… then on again, then off, repeat. I figured a kind of thermal overload was happening.
Barring some future repair, the only work around I could come up with was letting the power supply cool down by leaving the TV unplugged for some time and then trying again. That worked for a while, but the problem got worse over time. Finally, it would no longer power up at all without the above relay cycling.
I found a couple other references to the symptoms online, which confirmed my suspicion: capacitor plague (or as I’ve always called it: “puffy cap syndrome”). I’ve worked on this problem in the past to good success.
So I finally got around to cracking this TV open and taking a look. Sure enough, it was one specific capacitor, a much easier job than the last time I worked on this kind of failure. CB850 was the offending reference designator, a 1000uF 10V electrolytic.
Here’s a closer view of what we’re looking for to identify a “puffy cap”:
I had some left over 870uF caps from the last repair batch I did a decade ago. Though the value wasn’t quite high enough, I suspected that it was good enough. And fortunately, it was the same pin pitch, radial mount, through-hole.
Voila, the TV is working again!
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