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**370forlife** · 03-12-2010, 02:33 PM

Re: (ASK) what mod should be do in this psu ?

This power supply looks to have an ok design, just uses parts that are a bit small. Heatsinks are ok sized, transformer is a 33 size, 4 baby diodes on the input.

I would start with a recap. Then move up to a transient filter. Then, replace 4 diodes on input with bridge rectifier. If you really want to get extreme, replace some secondary schottky diodes with larger capacity ones.

**ibet** · 03-13-2010, 09:42 AM

Re: (ASK) what mod should be do in this psu ?

thanks for the reply

okay then, i can do recap my self ..
but i don't understand the mod of transient filter ( the component, size of the component ) and the bridge rectifier too ..

what component should i do for the transient filter and bridge rectifier part ?

**370forlife** · 03-13-2010, 11:27 AM

Re: (ASK) what mod should be do in this psu ?

Do you have any old psu's laying around you could gut for parts? That would be the best place to get parts for things like transient filters or bridge rectifiers. (though I don't recommend taking apart good psu's just to fix up a bad one, one that dosen't work or a old AT power supply might work)

Things like X caps, Y caps, and bridge rectifiers can be bought pretty easily and cheaply (don't know about the availability where you live,) but line filters are a little harder to find cheaply. My stash of them are all salvaged from psu's.

This is a bridge rectifier:

I labeled which legs are which. To replace the diodes with the bridge rectifier, quite simply remove all 4 diodes. The positive leg of the bridge rectifier goes in any hole that connects to the positive leg of the primary caps, the negative leg goes in any hole that connects to the negative leg of the primary caps, and the AC legs go in the holes that are live and neutral coming from the transient filter.

That I how I *think* it would connect with your power supply. A underside shot would clear it up.

Attached Files

**ibet** · 03-14-2010, 12:17 AM

Re: (ASK) what mod should be do in this psu ?

okay, just changed the four diodes to one PBU 805 bridge rectifier ( 8A @ 600V ) .
now the line filter part which i still don't understand at all ..

does it have specification ? and what recommended part for a 300-400w unit for the line filter part ?

and one more thing ..
what caps did u recommend for the recapping part ?
i can't find any japanese caps here in my town ..
gotta go to Jakarta to buy the caps ( and also the line filter )

**japlytic** · 03-14-2010, 03:17 AM

Re: (ASK) what mod should be do in this psu ?

Several corners have been cut in this power supply, especially having no EMI/RFI filtering.

**ibet** · 03-14-2010, 04:46 AM

Re: (ASK) what mod should be do in this psu ?

@japlytic
what does that mean ?
i don't understand ..

**etnietering** · 03-14-2010, 07:19 PM

Re: (ASK) what mod should be do in this psu ?

EMI = ElectroMagnetic Interference
RFI = Radio Frequency Interference

Switching power supplies operate and many KHz, and if they're just hooked directly into the mains, they can feed this many KHz signal back into the 50/60Hz mains. Which can cause other devices (especially AM radios) to not work properly. An EMI/RFI filter filters out this noise, making sure it doesn't escape back to the mains. Also, it keeps interference that other devices may be creating from interfering with the operation of the power supply.

If I remember correctly (I looked it up once), this is how it works:
X caps - usually film caps, connected across Hot and Neutral, filter out common mode noise. Must be rated X1/X2
Y caps - usually ceramic, although sometimes film caps, connected between Hot and Ground (Earth), and Neutral and Ground (Earth), filter out differential mode noise. Must be rated Y1/Y2/Y3
Filter coils - coils with 2 windings, wound in such a way that they filter out both common and differential mode noise. You must be careful installing them, otherwise you could hook Hot directly to Neutral and blow a fuse or circuit breaker or start a fire.

The X and Y caps are not polarized, but like I said you have to watch the filter coils. And be sure to remove the lame jumper wire, otherwise they won't do any good

Good luck!

**ratdude747** · 03-14-2010, 11:20 PM

Re: (ASK) what mod should be do in this psu ?

not to offend but the powersupply is not worth fixing IMHO. the tiny heatsinks, thin wire, counterfeit tranformer (that is so not a 35, maybe a 25), and small amount of secondary filtering make it nearly unfixable. the rest would be fixable... but it would not do much without fixing the rest... so find yourself a better psu. what kind of system do you run? if newer, then hypermicro.com has a nice 550w acbel for only $20! only catch is it has 8pin 12v, not 4 pin (you could splice in a 4 pin). if you run something needing an older 20 pin (not 20+4), check ebay for a good delta, hipro, enlight, etc.

gutless wonders never work in the end...

**ratdude747** · 03-14-2010, 11:33 PM

Re: (ASK) what mod should be do in this psu ?

sorry, hypermicro won't work for you, forgot you were in indonesia.

also i misjudged the heatsinks, a tad small but ok. the transformer also was misjudged. my bad. the wire is still thin, might want to remove the crap and solder in some thicker wires.

**ibet** · 03-20-2010, 03:00 AM

Re: (ASK) what mod should be do in this psu ?

i decided not to upgrade this old junker ..
maybe i should search another good one ..

have you heard Enhance 250w ?
got this for free from my friend ..
and it does small board, different i think .
i'll take some photos later ..

**momaka** · 03-20-2010, 11:23 PM

Re: (ASK) what mod should be do in this psu ?

Originally posted by ibet

i decided not to upgrade this old junker ..

You should still keep that PSU, though. It's actually not that bad at all. If you know of any TV repair shops around you, ask them if they have any TV/monitor boards that they don't need or want to get rid of. Those will usually have the components (X caps, Y caps, coils, etc.) needed to complete the input filtering of the PSU.
Old AT power supplies can be used for parts too, as 370forlife suggested.

Originally posted by ibet

have you heard Enhance 250w ?

If I remember correctly, they were a good brand. Your pictures will tell everything, though.

**ratdude747** · 03-22-2010, 07:43 AM

Re: (ASK) what mod should be do in this psu ?

enhance is a good one. much better than the POS you started this thread with.

some pics would be nice, though.

**paul_h** · 03-22-2010, 08:05 AM

Re: (ASK) what mod should be do in this psu ?

What's the benefit of a bridge rectifier over 4 diodes?
I know if you had a large rectifier you could mount it to a heatsink, but what else?
Inverter air cons have a bridge rectifier and it's one of the most common things to fail in their circuitry.

edit: Also why do the primary caps vary so much, nearly every PSU I've bought in the last few years have had 1000uF, 1200uF and 1500uF primaries, while nearly all the old (and cheaper) PSUs in my junk pile have ~400uF caps like that one.

**stj** · 03-22-2010, 12:14 PM

Re: (ASK) what mod should be do in this psu ?

the rectifier will handle more current,
and bigger caps can absorb more crap on the mains before it effects the psu.

**ibet** · 03-27-2010, 10:16 PM

Re: (ASK) what mod should be do in this psu ?

sorry for the late response ..
i had school exams last week .

this is the photo(s) of the free Enhance 250w

**370forlife** · 03-28-2010, 06:47 AM

Re: (ASK) what mod should be do in this psu ?

Looks like you don't need to do anything to it. That thing is pretty crammed.

**ibet** · 03-28-2010, 08:56 AM

Re: (ASK) what mod should be do in this psu ?

i think the same, PCB is full of component, just put better fans into it and it works pretty well with quadcore + IGP + 1HDD + 1ODD + 2 stick of ram ..

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