replacing capacitor in PSU

Look harder. Try Googling.

On 1 Aug 2005 14:13:32 -0700, "orange" put finger to keyboard and composed:

If you are running on 240VAC you could use a single 330uF 400V cap.

- Franc Zabkar

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According to the header he's posting from Russia. Does anyone know what the line voltage is there?

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bad idea.

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On 2 Aug 2005 00:16:03 -0500, me put finger to keyboard and composed:

why?

- Franc Zabkar

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OK, thanks all, I'll try ordering it from that site (unfortunately it might get 'lost' in the customs ) BTW, I'm from Serbia and Montenegro and voltage here is 220V.

I've ordered them from 'Debco Electronics Inc', very very cheap 2$ per piece (other places want more than 4$), hope it will not be of bad quality, and that it will arrive in a year or two, heh

Any capacitor of same value (or slightly higher) with a higher voltage rating will do fine. As this is a switch mode supply remember to use 105 degree parts or you'll be replacing that part pretty soon.

No necessarily. If running a dual voltage (120/240 VAC) power supply on 240 VAC, the input circuit forms a bridge rectifier with its output across the two main filter caps (in series). The quesiton is what happens with the centertap. If it's not used for anything else, then this approach can work, but you'd have to trace the input circuit completely to be sure it won't simply release smoke. :)

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In most switched mode power supplies, in 220V operation, the primary capacitors are placed in series, so in that case the idea is actually very usefull. You have to disable the voltage switch, of course.

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On 02 Aug 2005 08:59:36 -0400, Sam Goldwasser put finger to keyboard and composed:

In most PSUs that I've seen one could simply replace one of the two caps with a single 400V type, link out the remaining one, and then remove the two redundant wires going to the 240/120 selector switch. Some designs may have MOVs in parallel with the caps, in which case these should be removed.

By coincidence, yesterday I dismantled a Sony TV set which had a PSU which was configurable for single or dual capacitors. The Australian version of this set had a single 560uF 400V cap, and the other cap was linked out. The PCB real estate allotted to the 400V cap was slightly larger than for the 200V one.

- Franc Zabkar

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On Tue, 02 Aug 2005 15:05:26 +0200, snipped-for-privacy@panic.xx.tudelft.nl put finger to keyboard and composed:

The switch is open in 240VAC operation so it doesn't need to be disabled, but removing the two wires is a good precaution. I do it as a matter of course whenever I open a PC PSU.

- Franc Zabkar

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, so in that case the idea is actually

an important note...

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On 3 Aug 2005 17:37:54 -0500, me put finger to keyboard and composed:

Not really. In a 240V system the voltage switch is open. I'd still remove it, though, but for reasons of redundancy and added security, not necessity.

- Franc Zabkar

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You can use one of same or higher voltage and similar uF rating, doesn't have to be exact.