Bad Samxon GS in Hyundai HSC-1170NA STB
We still rely on analog cable here but the cable provider has introduced digital coding for the movie channels (HBO, Cinemax and the like), so for about 2 years IIRC we've had this STB. Lately it would display "no or bad signal" on most channels, and the ones which it did receive would skip badly. Cable checked out fine and mom couldn't find the warranty so i proceeded to take it apart. I'd just fixed the TV i'd been putting off for months (had diagonal lines at the top of the picture, bad caps in vblank circuit), so i thought i'd take a look at the STB as well.
Visual inspection revealed no problems, however the 8v rail read 5.2v. That's more than a bit low if you ask me. Checking with the ESR meter showed a 16v 220uF 85C Samxon GS with an ESR of about 2 ohms on that rail. I replaced it with a 470uF 16v 105C YC cap, now 8v came in at 7.79v and STB works fine again.
So is this a bad series, or was it simply a consequence of using general purpose 85C caps in a demanding and hot device? All rails have complete pi filters so i guess this thing is fairly critical about ripple.
Visual inspection revealed no problems, however the 8v rail read 5.2v. That's more than a bit low if you ask me. Checking with the ESR meter showed a 16v 220uF 85C Samxon GS with an ESR of about 2 ohms on that rail. I replaced it with a 470uF 16v 105C YC cap, now 8v came in at 7.79v and STB works fine again.
So is this a bad series, or was it simply a consequence of using general purpose 85C caps in a demanding and hot device? All rails have complete pi filters so i guess this thing is fairly critical about ripple.
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