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PC Power Supply Discussion Troubleshooting and discussion of computer power supplies

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Old 03-29-2018
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Default Worst units you've ever disassembled?

What are the worst units you've ever pulled apart? Do you have any pics of them?

Worst I've seen so far: https://imgur.com/a/1EXVU
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Old 03-29-2018
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If that's the worse you've seen, you haven't seen Powmax/Leadman PSUs!

https://youtu.be/q3wntQxT8M4?t=4m
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Old 03-29-2018
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I don't remember the Name but was an AT PSU with only one Heatsink. And I don't know if I did pics but probably not.‚
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Old 03-29-2018
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Quote:
Originally Posted by jonnyGURU View Post
If that's the worse you've seen, you haven't seen Powmax/Leadman PSUs!

https://youtu.be/q3wntQxT8M4?t=4m
I mostly work with OEM stuff in Dell/HP/Lenovo machines. I've seen worse online, but in person that was the worst I've seen.
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Old 03-29-2018
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@ awesomegamer919
"Your" unit looks like a "high end" crappy compared with "my" crappy one.
The PSU you posted had a semi complete EMI filter, two large bulk caps rated at 105 degree, a normally sized primary transformer, 2 coils on the secondary along with more filtering caps and is rated normally at 14 Amps on 12V rail. Instead the PSU I posted some time ago, apart from being more crappy, is rated at 27 Amps on 12V rail.
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Old 03-29-2018
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Quote:
Originally Posted by Al3xand3r View Post
@ awesomegamer919
"Your" unit looks like a "high end" crappy compared with "my" crappy one.
The PSU you posted had a semi complete EMI filter, two large bulk caps rated at 105 degree, a normally sized primary transformer, 2 coils on the secondary along with more filtering caps and is rated normally at 14 Amps on 12V rail. Instead the PSU I posted some time ago, apart from being more crappy, is rated at 27 Amps on 12V rail.
TBF my PSU was rated for 34A on the 5V rail and whilst it did have workable bulk caps, they had the very small issue of leaking Yours certainly does take the cake on overall crappiness though, single toroid coil, no EMI filter, no Pi coil
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Old 03-29-2018
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Quote:
Originally Posted by awesomegamer919 View Post
TBF my PSU was rated for 34A on the 5V rail and whilst it did have workable bulk caps, they had the very small issue of leaking Yours certainly does take the cake on overall crappiness though, single toroid coil, no EMI filter, no Pi coil
YEP.

Another difference is that your sample is a old one but my sample was taken from an recent mid range build and it sell yet like hot dogs because most of people doesn't put accent on the PSU quality, sadly.
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Old 03-29-2018
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Quote:
Originally Posted by Al3xand3r View Post
The PSU you posted had a semi complete EMI filter, two large bulk caps rated at 105 degree...
I'm still not convinced the primary caps need to be 105C

https://www.repairfaq.org/sam/smpsfaq.htm

"
Electrolytic capacitors exist in (at least) two different temperature ratings: 85 C and 105 C. The latter are obviously more temperature resistant. Unfortunately they also tend to have a higher ESR than their 85 C counterparts. So in an application where the heat is due to I^2 * ESR dissipation, the 105 C type may actually be a *worse* choice! If the heat is due to a nearby hot heatsink then 105 C is indeed a better choice.
"

that and the fact that the primary caps rarely fail.
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Old 03-29-2018
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"that and the fact that the primary caps rarely fail"
That is true for the simple voltage doubler circuit as used by the crap PSU's in this thread.

But as soon as you replace that with APFC one of the primary reasons for failure in my experience is the main filter cap:
It goes open circuit (no capacitance) with resulting fireworks in the PFC stage. (Shorted MOSFET's).
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This is most interesting; I have no experience with modern power supplies. I tend to recap OEM supplies rather than replace them.
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