The Capacitor Plague! Re-capping your 'tronics!

[Keatah]

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

 

Yehp, I had a Samsing 204B Flatscreen 1600x1200 monitor, and it sometimes took forever to power-up. And in the process of doing so it would flicker and sputter and sometimes the onboard logic would lockup. So I figured Samsung used shitty components in this particular model. The inverter circuit had CapXon electrolytics, the cheapest out there. The caps were creating noise (or not filtering it out) and this caused execessive noise in the faraday cage housing the display interface chip. (the absolutely brilliant Genesis GM5766af-aa from STmicroelectronics, it has *the* best resolution scaling in the industry). In addition, the caps weren't letting the inverter oscillator firm-up, resulting in sagging lumen emission. The caps were swollen hard and bulging, and upon removal I found them to be a couple uF short of the looney bin. So I got some nice new shiney muscular Nichicons and put them suck'rs right in. You could feel the heft when I put leads in the pcb via holes during repair. My monitor is now slap-happy bright and spurts right up eagerly when requested to do so, to be sure. It blows bright pixels right in my face.. Colors once again ooze forth in copious amounts. I mean it powers up immediately. And the supply seems to run cooler than it did, even when new. Upon further research, CapXon had stolen the electrolytic formula but didn't get the whole jobber down on pat. A somewhat less common failmode of caps is pre-fail leakage. But these CrapXon caps deteriorated and got noisy and weak. Just like your old car.

 

 

Howdy-har take charge of electrical filtration & pollution, take apart all your electronic stuff and inspect the caps. You get a bonus if you use a real DMM with capacitance functionality!!

Edited April 7, 2009 by Keatah

[AdeptRapier]

Ha! I laugh at your MMU with Capacitor function...REAL men use an LCR meter!!!

 

Bwwwwaaaaa Haaaaaa Haaaaaaaa!!!!

 

Adept Rapier

 

[gdement]

I once recapped a motherboard that seemed to straddle the timeframe when all the "stolen electrolyte" caps appeared.

All the caps of a particular size were the same brand and series. All except one of them were blown. The one that was still good was in parallel with several blown ones, so it's not like it was under any less stress. An ESR meter showed it really was still good.

 

The good one had a manufacturing date about 3 months earlier than the rest. It was kind of funny to see the date range pinned down like that.

[Carpenter]

Everyone should have one of these:

 

http://www.anatekcorp.com/blueesr.htm

[nathanallan]

My friend who works on vintage radios does recapping for those, but it's taken 50 years for them to go bad!

 

My new stuff has had caps go out, so I have to blame shoddy design or a bad way to save money. Sheesh. I want some capacitors from back in the day that last 50 years.

[gdement]

My friend who works on vintage radios does recapping for those, but it's taken 50 years for them to go bad!

 

My new stuff has had caps go out, so I have to blame shoddy design or a bad way to save money. Sheesh. I want some capacitors from back in the day that last 50 years.

Some caps on motherboards have extremely low ESR specs, and they sometimes run really hot, so it's not surprising they end up less reliable. The caps in an old radio wouldn't be good enough for lots of newer electronics.

There's long life caps available, but they also have more conservative specs.

 

Of course there's also the cheap Chinese caps that aren't trustworthy regardless of what the specs say (if you can even find a website for them).

 

I used some long-life Japanese caps when I recapped my 7800, based on the manufacturer's endurance ratings they should be good for decades. There's hardly any heat in there at all.

[+karri]

I once did a large run of PCB's with a lousy factory. They assembled lots of capacitors backwards. The units passed the tests but started to pop after a few months in use when the caps caught fire. Since then I have always taken a digital photo of every polarized capacitor at assembly time to catch these errors before soldering.

 

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Karri