Maxpower PL-300 one of the worst PSU'S ever

[jm20101]

Yesterday, I got some free computer stuff.
I also got this cheap ass power supply.
It was not working, so I opened it up....
It has one burnt fuse, burnt glue, leaked and bulged capacitors

I have some pictures, and made a video

Should I replace also the caps that are not leaking? Or isn't it the worth to fix it?

[tom66]

Re: Maxpower PL-300 one of the worst PSU'S ever

It looks like it has an active PFC board on top, so it's not entirely surprising the main power supply board is quite small. Still, it does look pretty poor. Fake Rubycons!

[jm20101]

Re: Maxpower PL-300 one of the worst PSU'S ever

It looks like it has an active PFC board on top, so it's not entirely surprising the main power supply board is quite small. Still, it does look pretty poor. Fake Rubycons!

Yes it had PFC, its quite strange that the 'fake branded rubycons' are branded JEE, but have a rubycon vent.....

[goodpsusearch]

Re: Maxpower PL-300 one of the worst PSU'S ever

This is a good 300W peak power supply.

It is the APFC version of Maxpower PL-300.

I have an identical psu that I recapped with janapese caps and it is working for 2 years without any problem powering a P4 1.5GHZ SDRAM computer.. It has decent heatsinks, 30A rectifiers for 5V and 3.3V, 13009 main switching transistors and 2200uF output filter caps and some coils. Please report any differences in your sample.

This is mine before the recap:
https://www.badcaps.net/forum/showpo...87&postcount=4
https://www.badcaps.net/forum/showpo...&postcount=118

And here you can see the changes that I made:
https://www.badcaps.net/forum/showpo...&postcount=121

Btw that project helped me learn that you can't replace the 12V ultra fast rectifier with a schottky unless it has 60V or more repetitive peak reverse voltage.

[jm20101]

Re: Maxpower PL-300 one of the worst PSU'S ever

This is a good 300W peak power supply.

It is the APFC version of Maxpower PL-300.

I have an identical psu that I recapped with janapese caps and it is working for 2 years without any problem powering a P4 1.5GHZ SDRAM computer.. It has decent heatsinks, 30A rectifiers for 5V and 3.3V, 13009 main switching transistors and 2200uF output filter caps and some coils. Please report any differences in your sample.

This is mine before the recap:
https://www.badcaps.net/forum/showpo...87&postcount=4
https://www.badcaps.net/forum/showpo...&postcount=118

And here you can see the changes that I made:
https://www.badcaps.net/forum/showpo...&postcount=121

Btw that project helped me learn that you can't replace the 12V ultra fast rectifier with a schottky unless it has 60V or more repetitive peak reverse voltage.

Thanks for the information.
Yours was in much better condition then mine.
I will replace the 2200uF and the 470uF caps.
But the problem is that the fuse of this PSU was burnt.
And I hope that someone know why the fuse was burnt.

[goodpsusearch]

Re: Maxpower PL-300 one of the worst PSU'S ever

Check for shorted transistors, rectifiers, diodes with the diode setting of your multimeter.

Try to remove the burnt glue because it can get conductive over time.

Check the APFC board for shorts.

I would replace every capacitor, even the tiny ones cannot be trusted.

[kc8adu]

Re: Maxpower PL-300 one of the worst PSU'S ever

this one isnt even in the running for the worst.imagine a "500w" rated unit with a board the size of yours apfc board and dummy weights in the case!

[lti]

Re: Maxpower PL-300 one of the worst PSU'S ever

this one isnt even in the running for the worst.imagine a "500w" rated unit with a board the size of yours apfc board and dummy weights in the case!

What about a power supply with no filter caps?

http://www.overclock.net/t/1310456/p...00w-psu-review

[tom66]

Re: Maxpower PL-300 one of the worst PSU'S ever

^^^^
It's probably a single-switch forward topology, not flyback. No way you'd get anything beyond 100W from a flyback without atrocious efficiency (like, sub 50%.)

And I really doubt there's no filter cap on the 12V. That doesn't mean ripple of 200mV, or 600mV, but ripple of at least 12Vp-p...

[jm20101]

Re: Maxpower PL-300 one of the worst PSU'S ever

OK, is is not the worst PSU, but the condition....
I replaced the 2200uF and 470uF caps, also the 5A fuse.
When I turn it on this is what happened

I think there are more problems with this PSU, but im just a beginner and don't know how to fix that. I have a multimeter and a capacitance meter.

[goodpsusearch]

Re: Maxpower PL-300 one of the worst PSU'S ever

Did you check all the caps with the capacitance meter? The big ones could be dead.

Did you check for shorts the primary transistors with the diode mode of the multimeter? Do the same at the secondary rectifiers and the APFC board silicon.

Did you remove the burnt glue that might be conductive?

[jm20101]

Re: Maxpower PL-300 one of the worst PSU'S ever

Did you check all the caps with the capacitance meter? The big ones could be dead.

Did you check for shorts the primary transistors with the diode mode of the multimeter? Do the same at the secondary rectifiers and the APFC board silicon.

Did you remove the burnt glue that might be conductive?

Sorry for the very, very late reply.
I put the PSU away, but today I have take a look at it.
I checked the two big capacitors and the values are more than 20% lower.
So, I replaced them for TEAPO capacitors. Now its finally working

But there is still a whining noise.
It could be a capacitor, or a coil.
I haven't recap all the capacitors so can a capacitor making that sound?
I can also post a video if need. Thanks for the help.

[goodpsusearch]

Re: Maxpower PL-300 one of the worst PSU'S ever

But there is still a whining noise.
It could be a capacitor, or a coil.
I haven't recap all the capacitors so can a capacitor making that sound?

Yes! Please change all the caps in it

[c_hegge]

Re: Maxpower PL-300 one of the worst PSU'S ever

The caps themselves don't make the noise, but a bad one can cause the coils to.

[jm20101]

Re: Maxpower PL-300 one of the worst PSU'S ever

Thanks again for the replies
It really helped me with fixing this PSU.
I will recap the PSU soon, and I hope that the noise will be away.