Mysterious Su'scons SG??

[Behemot]

I am telling you guys. Got this Acer AL1916W A which was blinking like christmass tree to repair. Full of Su'scons SGs, 470 uF/25V, one 1000 uF/25 V. I replaced them on sight (some Chemi-Cons KY 1500 uF/6,3 V and LXZ 1000 uF/25 V) and it is fine now.

But one problem is, according to ESR Micro v4.0 they are in 100+% condition. I mean, ESR was just OK (around 0,04) with capacitance slightly higher than nominal. Supposedly the display started to work OK when it was heated up, but it is not like they are bad when cold and get better when heated. I measured them at room temperature and I am telling you, according to these readings they are just fine. What am I missing?

[cheapie]

Re: Mysterious Su'scons SG??

Maybe the ESR is supposed to be lower than that? Also, I thought ESR went down with heat. I had a TV full of bad caps that worked fine if I warmed the caps up, and it's also working fine after a recap now.

[Behemot]

Re: Mysterious Su'scons SG??

Chemi-Con KY 1000 uF/16 V also has 0,04. I think in this range it is just fine. If it was like 0,5 ohm, I would start wondering, but some small hundredths…

[momaka]

Re: Mysterious Su'scons SG??

Try charging the caps with a 9V battery and then short their terminals with a screwdriver. Do this a few times. If you don't see or hear sparks, they are dead. I've had bad Nichicon HM from the 2001-2004 fiasco fool an ESR meter into showing them as good but slightly higher capacitance. After trying my 9V test above, I confirmed all of them were dead indeed. The high capacitance showed probably due to high leakage current.

[Behemot]

Re: Mysterious Su'scons SG??

Yeah all four are sparking.

[momaka]

Re: Mysterious Su'scons SG??

Should be fine then more or less. Not sure why the monitor is picky, though. Perhaps the problem was something else, like a bad joint or bad connection somewhere, but after taking out the old caps and putting new ones, that somehow fixed it/cured it. Just guessing here, though.

[Behemot]

Re: Mysterious Su'scons SG??

The soldering quality was actually pretty decent, haven't found any suspicious joint.

[c_hegge]

Re: Mysterious Su'scons SG??

Maybe one of the caps had a bad joint. Having it work after heating it up can also be indicative of a marginal joint. It might have just expanded the solder enough to make contact. I've had that once with a motherboard once. One of the DIMM slots wouldn't work unless you heated it up first. After re-soldering all of the pins, it worked fine.