Re: Dell Optiplex GX280 no boot and fan going crazy
Good info, thanks. Thing is, I'd like to find out before recapping if it's the caps or cracked solder balls, so I think I'll just "spring load" the HSF first to see if that makes any difference.
Thank you to the guys at HEGE supporting Badcaps [ HEGE ] [ HEGE DEX Chart ]
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Re: Why do they use a 10V cap instead of a 6.3V cap?
While I'm not sure where exactly those 50V pulses come from, rectified AC before filtering can have peaks I think about 1.414 times higher than the nominal voltage, and that's about 7V peak for 5V nominal, and the cap should be rated for that.
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Re: identifying SMD ceramic capacitor damage
SMD ceramics themselves are fairly reliable, but if they do fail because of spikes or overvoltage, chances are good that something else got fried, too. When they do fail w/o overvoltage, that's often physical because of stress levels, or the failure is caused by other external factors, often related to soldering, etc.
You could probably test them with a good capacitor tester, but I think the fault lies elsewhere.
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Re: Dell Optiplex GX280 no boot and fan going crazy
I measured (in circuit) the 1800 uF caps (9) next to the CPU socket, and depending on frequency, they're about 1550 - 1600 uF. Definitely less than 1800 but within 20%.
The 1000 uF/16V caps are about 850 uF each, also a little on the low side, but also within 20%.
Kinda hard to figure out what to do.... it's not like a 1000 uF cap measuring 125.
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64 meg NVIDIA AGP card
Had some issues and pulled the card, but I can't decide if those 470 uF 10V caps are bad or not.
Did anyone replace caps like those?
Oh, and for some extra 'fun', they are surface mounted...
TIA...
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Re: Checking ESR and Capacitance
For electrolytics, there's no such thing as 'normal tolerance'. You need to consult the data sheet.
Back in the 80's, lots of electrolytics had a tolerance of -50% +100%, but due to advancements in technology, I don't see them much any more.
As for whether a higher value is safe or not, that depends a lot on the circuit. In many cases much higher values will be OK, other times they can cause problems....
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Re: Dell Optiplex GX280 no boot and fan going crazy
I have a small desktop GX280 that is mostly dead. I thought it was a cap problem, but after reading this thread there's another possibility, a cracked solder under a BGA, and I don't think I can do much about that.
The caps I've seen in repair kits are 1500uF 6.3V and 1800 uF 6.3V, and there are nine of the latter next to the CPU socket.
Did anyone ever successfully repair this board (see attachment) by recapping? Which caps were replaced? How did the caps fail?
In addition to the 9 caps next...
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