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Old 04-20-2012, 04:53 AM   #1
Hatibu
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Default HELP .. Dell optiplex 745

I have Dell Optiplex 745 PC (Tower), Few month ago i changed the bad Capacitors
[ 2200uf, 6.3v ]. It was working fine after that. but few weeks letter it begins to Speed the FAN. i tried to change the capacitor again.. then it works fine but the problem repeats after few days. what should i do.
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Old 04-20-2012, 12:24 PM   #2
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Default Re: HELP .. Dell optiplex 745

If it's anything like the GX280 reseat the RAM. There's no reason the walking RAM problem should only affect the GX280.
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Old 04-25-2012, 02:40 PM   #3
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Default Re: HELP .. Dell optiplex 745

What was the original caps (manufacturer and series), and what did you replace them with?
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Old 04-25-2012, 04:52 PM   #4
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Default Re: HELP .. Dell optiplex 745

ORIGINAL: 2200uf 6.3v KZJ
REPLACED: 2200uf 6.3v RLP
also i tried to replace with (2200uf 6.3v KMG) But the problem was nt solved.
..This time The Fan starts normal then Speed increase slowly up to maximum! :s It shows Message "Alert! CPU fan failure."
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Old 04-25-2012, 11:25 PM   #5
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Default Re: HELP .. Dell optiplex 745

Your replacement caps aren't good enough. RLP is made by Ost and Ost caps aren't very good. In fact, they often fail without visible signs. The KMGs are most likely made by United Chemicon. KMGs are general purpose caps, not intended for use on the motherboard's power rails.
What you need is either Nichicon HM (HN and HZ will also work), Rubycon MBZ (MCZ will also work), or Sanyo WG. (I think Samxon GC and GD will also work, but I'm not 100% sure).
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Old 04-26-2012, 12:31 PM   #6
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Default Re: HELP .. Dell optiplex 745

Thanks "momaka" . I will go n try to find those cap.. type, Then i will give feedbac
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Old 05-01-2012, 10:03 AM   #7
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Default Re: HELP .. Dell optiplex 745

i tried to find The Capacitor types as u adviced me, but i didin't get any of what u mentioned. I found R.M capacitors. (2200uf, 6.3v). But the Size is not exactly as ones on the motherboard. So i need to confirm frm u if its gud to use those R.M, I dont knw the Manunfacturer of R.M capacitors.

...i also found FJ Capacitors, bt they are smaller than the original ones in Motherboard
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Old 05-02-2012, 07:28 PM   #8
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Default Re: HELP .. Dell optiplex 745

Quote:
Originally Posted by Hatibu View Post
i tried to find The Capacitor types as u adviced me, but i didin't get any of what u mentioned.
You can actually find those here at the badcaps.net store:
http://www.badcaps.net/pages.php?vid=23
http://www.badcaps.net/pages.php?vid=22
Generally, international shipping is $8, but I would advise you ask Topcat (badcaps.net owner and admin) first to see if he ships to your country.

Quote:
Originally Posted by Hatibu View Post
I found R.M capacitors. (2200uf, 6.3v). But the Size is not exactly as ones on the motherboard. So i need to confirm frm u if its gud to use those R.M, I dont knw the Manunfacturer of R.M capacitors.
I never heard of R.M. either. Probably not good.

Quote:
Originally Posted by Hatibu View Post
...i also found FJ Capacitors, bt they are smaller than the original ones in Motherboard
Do those have a little M in a box? If so, that would be Panasonic FJ. Those are very reliable caps. Not sure if they are up to spec with the KZJ, but they sure are better than the Ost RLP and more suitable than the United Chemicon KMG caps.
If you can't buy online, then use the Panasonic FJ caps. Like I mentioned, they aren't up to spec with United Chmicon KZJ, but they *may* work. Don't bother with the Ost RLP and United Chemicon KMG (Ost is not a good brand in general, and KMG are only suitable for general purpose stuff - i.e. not for switching power supplies and motherboards).
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Old 05-03-2012, 08:29 AM   #9
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Default Re: HELP .. Dell optiplex 745

I will try those Panasonic FJ, Then i will let u know..
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Old 05-04-2012, 09:31 AM   #10
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Default Re: HELP .. Dell optiplex 745

Panasonic FJ didin't work, after replacement the fan speed increases slowly up to maximum. ...i never find Other Manufacturer Capacitor of 2200uf,6.3v. There is only Those i mentioned above, maybe i should keep on looking.
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Old 05-05-2012, 11:41 AM   #11
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Default Re: HELP .. Dell optiplex 745

You might have more bad capacitors than those you replaced (do you got an ESR tester?). Also, you might have a look at the PSU (or try another).
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Old 05-05-2012, 03:05 PM   #12
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Default Re: HELP .. Dell optiplex 745

I Dont have ESR Tester, and I'm new in these electronic things.
..Also i don't think there is a problem with Power supply because i did swap from a working Pc.
BUT the first time i saw these Bad capacitor in Motherboard [i mean those 2200uf,6.3], i also checked the Power supply and also there was a 2200uf,16v Capacitor with a Bulging vent on the top. i did replace it and the comp was working fine. the problem has just raised from Nowhere (:, Fan speeds up as the PC Boot.
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Old 05-06-2012, 04:08 PM   #13
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Default Re: HELP .. Dell optiplex 745

If you only replaced capacitors that where visible bad, you probable has more bad capacitors. We use ESR testers to find those who are not visible bad, but still doesn't comply with specifications. From the kits sold on this site, I would guess that all capacitors above 680uF are suspect.
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Old 05-07-2012, 03:42 AM   #14
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Default Re: HELP .. Dell optiplex 745

I wouldn't overlook the 220uF ones either as experience from the the older 620 proved.
I think Dell did upgrade these in the 745 to 105c caps but even still they are worth checking.

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Old 05-07-2012, 10:59 PM   #15
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Default Re: HELP .. Dell optiplex 745

Let me work on how to use ESR testers then. i'm new in these electronic things . Anyway thanks.
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