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Comment by mrguyorama | Hacker News Reader

I have seen an (anecdotal) large amount of capacitors failing in consumer televisions. I recently replaced one in a friend's TV. These capacitors are supposed to have rated lifetimes of roughly the lifetime of the TV, so why are they failing in normal use? Is there another Dell situation, where a big batch had slight issues?

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The capacitor plague was never fully resolved. There are still a lot of attractively cheap but highly unreliable electrolytic caps on the market. Electrolytic caps represent a substantial proportion of the BoM of most commodity products, so there will always be the temptation to take a chance on off-brand caps. Even crappy electrolytic caps tend to outlive the warranty period and most customers are completely unaware of the issue, so there's very little incentive to spend the extra money on quality caps. In more discerning markets (enthusiast PC components, high-end hifi), Japanese electrolytic caps are a meaningful selling point.

https://en.wikipedia.org/wiki/Capacitor_plague

For that matter a lot of higher end PC components will advertise "no electrolytic caps" or "all solid state caps" as a feature.

>I have seen an (anecdotal) large amount of capacitors failing in consumer televisions. I recently replaced one in a friend's TV. These capacitors are supposed to have rated lifetimes of roughly the lifetime of the TV, so why are they failing in normal use?

The point IMHO revolves around "What is the expected lifetime of a TV (nowadays)?"

More anecdata, I own a "large" 32" Sony Trinitron that is incredibly heavy and that works just fine (touch wood) since 2002 or so.

I also had a smaller Mivar that lasted more than 30 years (if I recall correctly 32 years 1984-2016).

More recently (like 2013 or 2014) I procured for a friend's project a number (20) of (admittedly el-cheapo) Hi-Sense 32" LCD's, 3 or 4 failed in about 25 months (or one month beyond the 24 months covered by warranty) and 2 failed within warranty period (but the importer/assistance center closed before that anyway), of these most were capacitors related issues (one was simply a cold solder joint). But - besides the repaired ones - the remaining 13 or 14 still work just fine.

My understanding was about a decade ago, they were designed for 5ish years of average use

My 50-inch Pioneer PDP-5060 plasma (720p) lasted from late 2005 to 2014. I felt that was a short lifespan. I replaced it with one of the last plasmas sold, a 51-inch Samsung, and after four years a vertical line appeared. Now there are two. It is failing. That seems short to me. (OP)

My parents still have a 32" Panasonic LCD from the early 2000s as their main TV. The buttons on the remote are worn out, but the TV still works fine.

It has HDMI (720p or 1080i) so they have a Roku connected to it so they can watch streaming services. It has previously been supplied by DVD, VHS and terrestrial TV, all of which are now defunt :D

I've been wondering whether it's worth opening it up, as the inside must be full of dust.

The electrolytic cap market supplies a wide variety of quality levels and is permeated by counterfeit products. Ensuring that you actually use genuine components that will perform to spec is very difficult for anything built to a price. The "Dell situation" didn't start or end with Dell.

- The lifetime rating of the capacitor is at nominal ripple current and frequency at a given temperature. Exceeding current or temperature or dissipation (due to higher frequency loading) generally reduces life time by a power law. Conversely, lower stresses generally improves life time manyfold.

- Cheap electrolytics will barely meet their spec and will surely not meet their life time.

- No reason for a consumer good to last longer than the average hours used during the warranty period.

High-quality, generously dimensioned electrolytics (that aren't plagued by particular defects) will last many decades.

Samsung had a batch of these too; I suspect it's a combination of iffy suppliers and designing things exactly to the spec. Thermal design feels like it's often glossed over, especially with cables going everywhere and interrupting airflow.

On the other hand, if it's common knowledge that everyone overbuilds for tolerances on capacitors, it's easier to not feel bad about putting 95C electrolytic fluid in a can marked 105C if you "know" that it's common to bump up the rating by some factor when ordering parts.

I just had my several year old Samsung 65" UHD TV fail from a bad power supply. I strongly encourage anyone able to use a screwdriver to look at the web before tossing a TV or committing to an expensive repair. My case appears to be typical. A couple dozen screws release the back. There is a power supply board somewhat larger than a piece of notebook paper, and two smaller boards which are the LCD drivers and the god awful 'smart' junk they made me buy to get a display. The power supply board is not made by Samsung, you can get a replacement for about $60US. Swapping it is just 6 screws and two easy release connectors.

I went in planning to replace capacitors, but none of mine had visible signs of damage and my board was showing thermal discoloring around other components, so I went with the new board.

Safety note: Turn the thing off, unplug it, and let it sit for hours before you go in. Probably longer than necessary, but I'm sure you have something else to do. These power supplies make >200V outputs for the LED backlights, on the "cold" side of the board isolated from the mains… so the cold side is packing more voltage than the hot side. Remember this if you are tempted to probe a live board.

WRT to the safety note, it's not as bad as CRT TVs where you had to worry about discharging voltages of 25 kV or so, but point taken.

The power supply on my TV died after about 5 years, but since it was an external brick it was trivial to cut the connector off and toss it on an old Dell laptop power supply (the TV wanted 20v, the Dell supply gave 19.5v, but it seems to work fine). I see now that official replacement power supplies are also available on Amazon for $16 if you don't want to hack together a replacement.

Update that no one will read: I went to recycle the old power supply board today and shocked myself twice, then I "petted" it with a strip of aluminum foil and got a really good CRACK out of one of the capacitor banks. So that's more than a week after it was unplugged. I thought those electrolytics would leak faster.

It was in fact a Samsung TV

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