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View Full Version : Recapping an ABIT BP6 capacitor questions



Unknown_K
February 20th, 2017, 06:14 PM
I have a dead Abit BP6 motherboard (the one with dual Celerons) and need some advice on replacement capacitors.

The board had 12 x 6.3V 1500uf capacitors (that read in at 3000uf when tested so bad) and 12 x 10v 1000uf capacitors (which read in spec but I am replacing them anyway).

Questions are: in my parts stack I have 6.3V 1800uf parts (close enough?) and 16v 1000uf (taller but same diameter I assume higher voltage is ok?)

Hugo Holden
February 20th, 2017, 06:42 PM
In most cases, when replacing power filter electrolytics it is better to use higher voltage rated ones (if they fit) as they tend to be longer lasting and they have lower leakage at the operating voltage. There can be differences in the capacitor's ESR values, of capacitors with different voltage ratings, but usually this is not significant enough to cause difficulties.

The stated uF values for many electrolyitcs are pretty loose too, often +/-50% or more compared to the electrolyic's uF label. The physical size dictates what voltage rated cap of some uF value will fit in the space of the original. So the replacements can be the same capacity or a little higher and the voltage ratings need to be at a minimum the same as the original, but can be higher, twice or more no issues. There are some cases where the capacity could be too high for the application, but there are few, if any cases, where using a higher voltage rated cap would cause any significant trouble. Since more modern electrolytic caps are smaller than older designs, often it is possible to fit a higher voltage cap of the same uF value in place of the original part without difficulty.

This size difference between new and old capacitors has been exploited in the restoration of tube based equipment. For example a 2.2uF 400V electroytic cap from the 1940's era is about the same size as a modern polyester/polypropylene 2.2uF 400V capacitor
allowing the electrolytic to be dispensed with completely, in favor of a superior part. However with the high range of uF values of capacitors in semiconductor equipment its not an option as its only possible for values below a few uF. Another example I was able to replace the 2.2uF electrolytic coupling caps in the gun amplifier circiuts of my IBM5153 monitor with high voltage poly capacitors which were able to fit and are far superior.