Hi. I bought PSU N93CX (From Maplin UK), When connected to a load, full voltage is not available & current supplied is low. From searches, I have reason to believe that C28 is causing this fault. I wish I had the circuit diagram for this PSU, but I don't. It's essential (I assume) that I replace C28 with the right class or a class that is not a problem. The AC mains here is 230V. The original capitor is a brown colour with glossy surface finish and the radial spacing is 27.5mm. The markings on it are 105K, 250VPF. Can anyone comment about what I should be looking for as a superior replacement for the original capacitor? I think in this case C28 is being used in an application with "high current stress", but cannot verify that, not having the schematic. So, I think the class or the spec. needs to refect this (sort of guessing). Thanks. (EDIT: I have been looking at KEMET products).

 

Hi. I bought PSU N93CX (From Maplin UK), When connected to a load, full voltage is not available & current supplied is low. From searches, I have reason to believe that C28 is causing this fault. I wish I had the circuit diagram for this PSU, but I don't. It's essential (I assume) that I replace C28 with the right class or a class that is not a problem. The AC mains here is 230V. The original capitor is a brown colour with glossy surface finish and the radial spacing is 27.5mm. The markings on it are 105K, 250VPF. Can anyone comment about what I should be looking for as a superior replacement for the original capacitor? I think in this case C28 is being used in an application with "high current stress", but cannot verify that, not having the schematic. So, I think the class or the spec. needs to refect this (sort of guessing). Thanks. (EDIT: I have been looking at KEMET products).

Try the following:
https://files.elv.com/Assets/Produkte/7/719/71969/Downloads/71969_nrp2050_data.pdf

Kemet R75 capacitor, rated 400VDC, 220VAC.

There's an old repair post on eevblog.

 

Yes, the eevblog post does terminate with the capacitor selected. In my post I was just wanting to gain some more technical understanding. It would have been possible to identify the original capacitor and replace with that, In that case, you would not need to know the capacitor's specification. Another approach is to understand the technical issues which inform about what is acceptable as a replacement. I'm on that approach in this post. For some reason, I've got it into my mind that class of capacitor, (like X2 class etc) is important, but actually, that other thread does not mention class. What it does is mention C28 needs to be suitable for "pulse use". And in fact, the data sheet for the R76 product never once mentions class, but does mention "Pulse Application". On the other hand a different product (R46 series) does mention class and is suitable for "across-the-line" applications. OK, so the class stuff is relevant to across the mains applications. C28 then must or should not be across the mains. (EDIT:As an an aside: I could do to get me an ESR meter).