Cheap PSU: Piece of junk or semi-decent?

[Behemot]

Re: Cheap PSU: Piece of junk or semi-decent?

There is most often none. Important is only the one which is on input filtration to discharge X and Y caps which can give you minor shock from the energy they store.

Usually nobody cares about input caps as the energy they store cannot go back through rectifying diodes. For that reason if you will ever test supply on live, have some 10k+ resistor and discarge the caps manually after disconnectign mains. I help myself by measuring their left voltage too. Otherwise you can get shocked or destroy some parts of the PSU if you will accidentally short some parts with the caps for example over the metal casing. I have some experience in this area

[TELVM]

Re: Cheap PSU: Piece of junk or semi-decent?

Aye aye. Lesson of the day: Don't fiddle with current sensing resistors .

The gray resistor is 2.6Ω, the pink one is 47.1Ω. As they are similar in form and size to the other four I thought it would be interesting to put them higher in the breeze .

Which ones are the bleeder resistors, those that discharge the two big caps after power off?

[goodpsusearch]

Re: Cheap PSU: Piece of junk or semi-decent?

Wait! You might want to put those resistors back the way they were! Those are not the same as the minimum load resistors on the secondary - the resistors in the 3 pictures above are for current sensing and putting them on long leads is not good! Besides, those don't run that hot anyways.

+1

This looks scary

[momaka]

Re: Cheap PSU: Piece of junk or semi-decent?

Well I don't think these resistors will cook my fresh caps anymore .

https://www.badcaps.net/forum/attach...5&d=1353379557

https://www.badcaps.net/forum/attach...6&d=1353379557

https://www.badcaps.net/forum/attach...7&d=1353379557

Wait! You might want to put those resistors back the way they were! Those are not the same as the minimum load resistors on the secondary - the resistors in the 3 pictures above are for current sensing and putting them on long leads is not good! Besides, those don't run that hot anyways.

[TELVM]

Re: Cheap PSU: Piece of junk or semi-decent?

Well I don't think these resistors will cook my fresh caps anymore .

[TELVM]

Re: Cheap PSU: Piece of junk or semi-decent?

Thanks Tom!

[tom66]

Re: Cheap PSU: Piece of junk or semi-decent?

The two caps are in series, creating a 400V capacitor (with half the capacitance of the two capacitors.)

The peak voltage from 230VAC mains is about 325V.

[TELVM]

Re: Cheap PSU: Piece of junk or semi-decent?

Just a disturbing thought I've had. This Allied PSU came with 200V Su'scon primary caps, worked fine for many years powering a P4 Preshott, and I'm now replacing them with 200V Panasonics.

But it's 230VAC from the wall here around. Wouldn't have been better replacing with higher voltage big caps?

What's the relationship between voltage from the wall and the primary caps' voltage?

[Behemot]

Re: Cheap PSU: Piece of junk or semi-decent?

Oh you can delete this 2

[tom66]

Re: Cheap PSU: Piece of junk or semi-decent?

Yes, that is my point. But the fact of the matter is they are trying to substitute ordinary ceramics for y-caps. This is a safety issue.

[Behemot]

Re: Cheap PSU: Piece of junk or semi-decent?

They are not even trying to be Y caps. Just somebody put them in instead of Y caps. See all the difference?

[tom66]

Re: Cheap PSU: Piece of junk or semi-decent?

Not real Y-caps.

[Behemot]

Re: Cheap PSU: Piece of junk or semi-decent?

Yeah they're fakes.

[tom66]

Re: Cheap PSU: Piece of junk or semi-decent?

Yeah they're fakes. Sometimes you see genuine yellow/orange y-caps.

[Behemot]

Re: Cheap PSU: Piece of junk or semi-decent?

Average ceramics.

[TELVM]

Re: Cheap PSU: Piece of junk or semi-decent?

Are these real Y-caps?:

[tom66]

Re: Cheap PSU: Piece of junk or semi-decent?

Yellow Y-caps can still be real -- they don't HAVE to be cyan.

[TELVM]

Re: Cheap PSU: Piece of junk or semi-decent?

... I'm not familiar with the top logo though, the triangle looks very close to SamYoung's logo. Don't be confused.

Scroll down to the bottom: http://freespace.virgin.net/matt.wai...ogos/logo2.htm

Also:

http://how-to.wikia.com/wiki/File:Ic...onics_Corp.jpg

http://www.classiccmp.org/rtellason/...ctorlogos.html

[mariushm]

Re: Cheap PSU: Piece of junk or semi-decent?

You'll find them under M, for Matsushita.

From 1935 to October 1, 2008 the company name was "Matsushita Electric Industrial Co., Ltd."[4][5]

On January 10, 2008, the company announced that it would change its name to "Panasonic Corporation", with effect from October 1, 2008 to conform with its global brand name "Panasonic".[6] The name change was approved at a shareholders' meeting on June 26, 2008 after consultation with the Matsushita family.[7]

I'm not familiar with the top logo though, the triangle looks very close to SamYoung's logo. Don't be confused.

[TELVM]

Re: Cheap PSU: Piece of junk or semi-decent?

... I'm guessing this is going in the computer you posted in the "ghetto mods" thread? ...

Yep, this PSU is for the dinosaur PIII .


The fresh caps arrived .

It's going easier than I expected , except for the two little ones between the heatsinks. They were a PITA and needed tweezers & lots of harsh language to go into formation .

->LARGE · ->LARGE · ->LARGE

I'm leaving the n.16 2200uF 16V 12.5mm Ø for the end, to have room for fixing my resistor-cooling ghetto-mod. Also the two Panasonic big ones are a bit larger than the Su'scons and need some tweaking in the neighborhood for clearance.

BTW, I was puzzled when I couldn't find any 'Panasonic' marks on them, and even more puzzled when I couldn't find Panasonic in this list . Then I learnt that Panasonic was called Matsushita years ago, and that Panasonic caps are marked 'M' :