Electronics > Repair
bad caps on samsung lcd display
Skimask:
Keep in mind crappy caps aren't always the issue.
Take the case of an office that's warm in the first place, with the back of the monitor sitting on a desk in a west facing window. Back of the monitor gets hot, can only get so much heat out of there from convection. That'll kill any cap over time.
Or the idiots that put the exhaust fan from the PC blowing directly on the back of the monitor itself.
People, in general, are stupid...which is why I stay in business.
retiredcaps:
--- Quote from: Prime73 on July 03, 2014, 09:55:45 pm ---ok fair enough. but how do you know these are fakes? more general question - how to tell/measure apart a fake cap from a genuine one?
--- End quote ---
Buy them from reputable distributors like digikey, mouser, etc. Capacitors from ebay are 98% counterfeit. Dealextreme has also sold fake Sanyo capacitors.
The "recommended" brands are Nichicon, Panasonic, United Chemi-con and Rubycon. Each vendor has their own vent (top) style and bung (bottom). The datasheets for each capacitor will show you a picture of what the vents/bungs should look like.
As mentioned, your Sanyo's are obviously fakes because they have an X vent.
retiredcaps:
In addition, using the wrong series of caps will also cause them to fail prematurely.
In a SMPS, you will likely need low ESR caps. Caps like Panasonic FM or FR series.
PS. Replacing only the obviously bulged capacitors and thinking it is "repaired" is another newbie mistake.
wraper:
--- Quote from: Prime73 on July 03, 2014, 09:55:45 pm ---ok fair enough. but how do you know these are fakes? more general question - how to tell/measure apart a fake cap from a genuine one?
--- End quote ---
Measuring won't tell anything in many cases. Maybe if there is a huge capacitance/ESR inconsistency in one batch. One of the most obvious is wrong vent, maybe wrong marking, sleeve color. Capacitors should be bought only at reputable places as on ebay/aliexpress chances to get crap are close to 90-95%
Kostas:
Sometimes sleeve colour is ok, but sleeve placement is random between capacitors of the same "batch". I had a batch from ebay, too good to be true price, where most of the capacitors had the sleeve either too high or too low on the barrel. They also had wrong vent type (X instead of K).
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