"Magna" 300W ATX PSU (bad workmanship inside)

[Rulycat]

Here is a Magna 300W ATX PSU, with plenty of bloated JEE and other caps:

Primaries are HEC 330uf 200V (will change these when I get some other caps)

Now I said on the other thread about the electronic clock kit I was waiting on some caps off my dad. Well here they are in action! and before I get roasted for bad repair work or it's dangerous etc, this is just a "Will it work?" project, using what I now have, which is Jamicon 85C caps, Fake Nichicons and Fake Panasonic FR caps!

At least the values are a lot larger.

The 470uf 16 cap is actually that value, I just wrote it in red underneath by mistake.
Also the cap at the bottom right of the labeled image isn't "0v", it's "10v"

The cap replacements are as follows:

C10 (EMPTY) -> 2200uf 10V Fake Panny
1000uf 10v UNITE -> 2200uf 10v fake Panny
1000uf 10v UNITE -> 3300uf 16v fake Nichicon sitting off the board about 5mm!!!
1000uf 16v JEE (bloated) -> 3300uf 16v fake Nichicon sitting off the board about 10mm!!!!!!
1000uf 10v UNITE -> 2200uf 10v fake Panny
470uf 16V UNITE -> 470uf 25V Jamicon 85C (Yeah, I know, it's 85C and General Purpose!) Sitting off the board about 3mm
330uf 10V UNITE -> 2200uf 10v fake Panny
470uf 10v UNITE -> Jamicon 470uf 25V Jamicon 85C (Yeah, I know, it's 85C and General Purpose!)
1000uf 16V JEE (bloated, top right) -> 3300uf 16V fake Nichicon sticking off the board about 8mm!!!!!!!
and finally...

the worst offender of my recap....
47uf 50V cap (bloated out the bottom) replaced with...

Two Jamicon 100uf 25V in series for a combined 50uf 50V and probably way too much resistance!!!

Again, this is NOT a lesson in how to recap a power supply.I know full well what I've done is ridiculous. This is more a "I've got this stuff, will it work?" Before I did this, the volts would be all over the place, as in, my cheap £2 multimeter would show the voltages actually moving on the display up and down as it ran (with a dead HDD for some load)


Now it's stable.

So this is probably "How to get yourself Killed" but I thought it amusing to share nonetheless.

For some info

Transistors
CET 4.3B M2 - CEF02N6
D13007K (two) these are on the left hand side of the PSU where the primaries are.

On the other side...
LT 348STPR1020CT
LT 402 SBL2040CT
Last one is a mission to make out...CEPT703NL... think it also says 431YM

I';ve got a 35 size transformer here... Maybe I should see if i can solder it in and see if it goes POP?

Currently respraying the case in white with some no-name car gloss paint and might stick some LED's in the fan for fun.

You should take bets on when one of my relatives will turn up on the form and say "Sorry, Rulycat will no longer post as he has been killed"

[stj]

Re: "Magna" 300W ATX PSU (bad workmanship inside)

go to poundland and get a pair of safety glasses, or only run it covered - when a cap blows you DO NOT want it or it's contents to hit you in the face.

and a lot of us - including me, have experienced caps blowing clean across the room multiple times.

[Rulycat]

Re: "Magna" 300W ATX PSU (bad workmanship inside)

Doly noted stj

I replaced with a 35 size transformer as in the images attached - and used electrical tape to separate from the heatsinks (as I assumed it's not a good idea if those make contact with the heatsink)

PSU acts like it's dead except for 12V which produces 0.12V... I'm assuming the coil has too many windings as it's designed for a different PSU?

[everell]

Re: "Magna" 300W ATX PSU (bad workmanship inside)

I replaced with a 35 size transformer as in the images attached - and used electrical tape to separate from the heatsinks (as I assumed it's not a good idea if those make contact with the heatsink)

You could use a hacksaw to cut notches in the heat sink to allow plenty of space for the transformer. For a 300 watt power supply, the heat sinks definitely look over rated!

Be sure to wear those safety glasses. From personal experience, power supply components WILL explode.

[everell]

Re: "Magna" 300W ATX PSU (bad workmanship inside)

I think we need a new section in this forum titled "Will It Work Experiments". My thread on "Fun fixing IMicro power supplies" would have fit great in this section, along with this current thread. So what do you think?

[Rulycat]

Re: "Magna" 300W ATX PSU (bad workmanship inside)

That would be a good idea everell. Any ideas why the "new" transformer doesn't play nicely with the unit?

[everell]

Re: "Magna" 300W ATX PSU (bad workmanship inside)

Changing transformers is a risky business. EXTREMELY DANGEROUS. When you decide to send a power supply to the junk box as not fixable, leave the transformer soldered to the original pc board. I know it takes up extra space, but you will be able to come back to it later and trace which transformer leads go to which circuits. Then you have a chance of getting something to work.

Only once I tried changing a transformer randomly. It blew fuse, got very hot, and blasted several parts. If you want to learn how to fix these power supplies, and use salvaged transformers, LEARN to do it right. Transformer pins need to go to the right places. In your case, you were lucky. It simply did nothing. Once off the pc board it is very difficult to say for sure which winding is which.

[sam_sam_sam]

Re: "Magna" 300W ATX PSU (bad workmanship inside)

I think we need a new section in this forum titled "Will It Work Experiments".

This is really funny

My thread on "Fun fixing IMicro power supplies" would have fit great in this section, along with this current thread. So what do you think?

I like to see this

[Dan81]

Re: "Magna" 300W ATX PSU (bad workmanship inside)

Changing transformers is a risky business. EXTREMELY DANGEROUS. When you decide to send a power supply to the junk box as not fixable, leave the transformer soldered to the original pc board. I know it takes up extra space, but you will be able to come back to it later and trace which transformer leads go to which circuits. Then you have a chance of getting something to work.

Only once I tried changing a transformer randomly. It blew fuse, got very hot, and blasted several parts. If you want to learn how to fix these power supplies, and use salvaged transformers, LEARN to do it right. Transformer pins need to go to the right places. In your case, you were lucky. It simply did nothing. Once off the pc board it is very difficult to say for sure which winding is which.

I actually do PC PSU main transformer replacing and the worst to happen was it wouldn't turn on because of incompatible secondary pins.

Other devices though, that would be another story.

[Rulycat]

Re: "Magna" 300W ATX PSU (bad workmanship inside)

OK, so I should probably work out how the transformer is wound and which pins go where before doing anything again. I'll probably cut this one in half to see how it goes together.

[ChaosLegionnaire]

Re: "Magna" 300W ATX PSU (bad workmanship inside)

but does this also mean u can only use the same transformer on the same model of power supply? say i have another busted magna 300w with a burnt transformer and another magna 300w with a working transformer but failed pfc section, could i transplant the working transformer into the psu with the burnt transformer as a replacement?

[Rulycat]

Re: "Magna" 300W ATX PSU (bad workmanship inside)

but does this also mean u can only use the same transformer on the same model of power supply? say i have another busted magna 300w with a burnt transformer and another magna 300w with a working transformer but failed pfc section, could i transplant the working transformer into the psu with the burnt transformer as a replacement?

If they are identical it would be logical you could swap them... no?

[Dan81]

Re: "Magna" 300W ATX PSU (bad workmanship inside)

but does this also mean u can only use the same transformer on the same model of power supply? say i have another busted magna 300w with a burnt transformer and another magna 300w with a working transformer but failed pfc section, could i transplant the working transformer into the psu with the burnt transformer as a replacement?

Sure, you can.

It's a matter of matching the transformer pins on both sides (AC and DC side) when installing the new one and making sure BOTH supplies are of the same topology and pinout.

Have successfully transplanted three big transformers from a failed Deer (burnt 220v side, transformers were okay) to another one that was working but had those skimpy "ERL-33 / ERL-19(TOP)/ ERL-16" transformers installed.

[everell]

Re: "Magna" 300W ATX PSU (bad workmanship inside)

I replaced some wimpy IMicro transformers with some larger better transformers. Worked OK. Some other things to keep in mind....the base capacitors should be replaced....use 4.7 uF or 10 uF instead of the 1 uF or 2 uF that most of them use. Also you might need to go to switching transistors which can handle the additional power. The mains capacitors need to be at least 470 uF.....throw those wimpy 220 uF and 330 uF in the scrap pile.

Once rebuilt, even an IMicro power supply runs respectably. But IMicro will NEVER be as good as a Bestec ATX-250 12E.

[Dan81]

Re: "Magna" 300W ATX PSU (bad workmanship inside)

Well, I did do some rebuilds too.

For example, my main PSU is a nJoy (unknown OEM) whose prinary side was kaput, about 60-70% of it - switchers were gone, so were the main caps. A pair of 13009s, a standby switcher from an Delux/iMicro and a pair of two big Hitachi HP3 820uF caps later and it powers a Xeon X5450 just fine.

iMicro PSUs will just work fine with kind of any other generic cheapie that has a real ERL-35 (or 39, whatever it came with) in my experience. I had one that finally gave the ghost a year ago, but I clearly remember it for having installed a 35 size trafo by myself from a dead Kaisen unit. That transformer is still alive and kicking in a Linkworld LPK19-30 460W.

Nowadays I don't really do major rebuilds - just turning Deers into safe and cheap 250W units for various machines - I have one in my Pentium 3 500MHz machine and it's one of those "B" type units (the one with the reverse PCB orientation) and it is now with complete filtering and works real well without issues.

[momaka]

Re: "Magna" 300W ATX PSU (bad workmanship inside)

Currently respraying the case in white with some no-name car gloss paint and might stick some LED's in the fan for fun.

Can't wait to see some pics!

It would also be funny to try and sell this at one of your car "boot sales" that you guys do over there. I bet some young gamer kid will show up and try to buy it because of all of the LEDs.

Again, this is NOT a lesson in how to recap a power supply.I know full well what I've done is ridiculous. This is more a "I've got this stuff, will it work?"

No worries. I have "fixed" electronics like that of my own. Some of them even still work, supposedly.

On that note, your "fake" Nichicon and Panasonic caps don't look bad for fakes at all. In particular, those fine "T" vents on the Panny's actually look quite genuine. Now how funny would it be if those caps turn out to be not fakes?

go to poundland and get a pair of safety glasses,

+1000000000

I never test anything without my safety glasses, even if it's covered. Never know if something will fly off a vent opening and bounce to hit you in the eye. Maybe it won't be powerful enough to hurt your eye... but why even risk it?

On that note, I just don't understand how ElectroBoom on YouTube does this all the time and is not worried. Many of his latest videos, he puts a small electrolytic cap in an *AC* circuit on purpose (though looking as if he had no idea what he was doing ). And of course it goes *BANG* every time right in front of his face.

That would be a good idea everell. Any ideas why the "new" transformer doesn't play nicely with the unit?

You can't just pop in any different transformer in there and expect things to work. At the very least, the transformer has to match the topology of the PSU (half-bridge, 1T-forward, 2T-forward, etc.) AND the pins for _all_ of the windings have to match to the original (i.e. 12V rail goes to 12V rail, and etc.)

say i have another busted magna 300w with a burnt transformer...

I've never seen a burned/bad main PS transformer on an ATX PSU - ever.
5VSB traffos? - Yes, 1 or 2 (mostly in cheapo PSUs)
And inverter traffos from LCD monitors - plenty.

But main PS traffo... no, these just don't go bad. That said, there was a thread here recently where one person did show a PSU with what appeared a darkened main transformer in a non-working PSU and said everything else checked out fine in the PSU. But the thread never got a closure or any feedback from the O/P, so I still can't say if that one was bad or not.

In any case, you're not gonna see it often at all.

Nowadays I don't really do major rebuilds

Same here.

I have too many decent 250-350 Watt simple PSUs (oldschool Delta, HiPro, and LiteOn) now that just don't have as much time to be bothered with rebuilding any of the gutless PSUs. Some years back when I didn't have that many PSUs, though, I did think about rebuilding many of the gutless PSUs I have. And in fact, I still may do that some day when I have time. They are just not a priority, though, so anything else that comes in for repair takes precedence.

However, I did manage to rebuild a Deer and an L&C PSU some years ago. The Deer just needed a recap and minor mods here and there. The L&C needed caps, output coils, and EMI/RFI filter, among other things. Both still work. And the Deer PSU is actually still in use today in one of my Pentium 3 PCs. Given the low load from that PC, it works perfectly fine for it. Here is the Deer PSU, by the way:
https://www.badcaps.net/forum/showpo...&postcount=490
It's a Deer DR-250ATX.