Cheap PSU: Piece of junk or semi-decent?

[momaka]

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

Not surprised. Them Deers are tough cookies.

[TELVM]

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

... I think the Deer would have lasted longer, though ...

That one is still soldiering on and running fine, Oh Deer!

[momaka]

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

After discovering that one of the main switchers was also damaged, I decided to decomission the concoction .

I guess its time has come.
RIP TooQ

Tinkering with it was tons of fun and a learning experience, and most amazingly it lasted for 2~3 years in its frankenstein iteration.

It also prompted lots of good discussion in this thread .
I think the Deer would have lasted longer, though .

It's caps have been recycled and found a new home onboard an Enermax ENP500AGT that came OEM with an assortment of Jun Fu and Su'scon crap.

Nice!
Reusing and re-purposing is the highest form of recycling.

[TELVM]

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

My guess is the transformer might easily become saturated then, unless the other rails are loaded down sufficiently. (Even then, the transformer would saturate at a lower current, so the psu might not be able to do it's rated output without going bang) ...

^ Hum, you may have a point there, the main transformer always looked suspiciously small from the beginning.

After discovering that one of the main switchers was also damaged, I decided to decomission the concoction . Tinkering with it was tons of fun and a learning experience, and most amazingly it lasted for 2~3 years in its frankenstein iteration.


It's caps have been recycled and found a new home onboard an Enermax ENP500AGT that came OEM with an assortment of Jun Fu and Su'scon crap.

[ben7]

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

It *might* start with no load, but definitely something I would NOT try with a load. Will probably get terrible ripple on the 12V rail... if you can even call it a 12V rail - it might be closer to 6V than 12.

My guess is the transformer might easily become saturated then, unless the other rails are loaded down sufficiently. (Even then, the transformer would saturate at a lower current, so the psu might not be able to do it's rated output without going bang)
(If it would even cause it to saturate at all ... it's just a wild guess! lol XD)

-Ben

[momaka]

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

Heh heh I'm thinking about performing a little experiment ... what if I just cut off the shorted leg and put it back as a single-diode 20A rectifier ? Would it start?

It *might* start with no load, but definitely something I would NOT try with a load. Will probably get terrible ripple on the 12V rail... if you can even call it a 12V rail - it might be closer to 6V than 12.

As for the blow rectifier, check the snubber network for the 12V rail. Should be a ceramic cap and a low-resistance resistor (10 Ohms for Deers, IIRC) in series. Sometimes the ceramic caps go shorted on these Deers and cook the resistor. If the resistor goes O/C, you have no snubber network, and the voltage spikes from the transformer could get high enough to take out the rectifiers.

[goodpsusearch]

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

ΝΟΟΟΟ

[TELVM]

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

Heh heh I'm thinking about performing a little experiment ... what if I just cut off the shorted leg and put it back as a single-diode 20A rectifier ? Would it start?

[goodpsusearch]

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

Ahem , thas was an old mishap since solved, see here.

Ok.

Either the Repetitive reverse voltage was too low for that platform,

or else, something went wrong with the rectifier's insulation.

[TELVM]

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

The STPS40M60CTN +12V rectifier is definitely blown, once unsoldered from the PSU one of its legs is shorted.

Maybe the Repetitive reverse voltage was too low for that platform.

That's my best guess.

The secondary heatsink is directly connected to the rectifier's output pin? I don't see any insulation.

Ahem , thas was an old mishap since solved, see here.

schotky rectifiers usually have a snubber resistor&cap, was it there or added?

The OEM MBR20150CTP was a Schottky, so I'd guess yes, but I can't really tell.

[stj]

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

schotky rectifiers usually have a snubber resistor&cap, was it there or added?

[goodpsusearch]

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

Interesting.

Maybe the Repetitive reverse voltage was too low for that platform.

The secondary heatsink is directly connected to the rectifier's output pin? I don't see any insulation.

[TELVM]

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

My legendary 'TOOQ' frankenPSU concoction suddenly refuses to start. This PSU has not seen much use since it was frankensteined, just some hours a month powering a P4 retrocomp.

+5VSB is alive and well, but when I switch the PSU on the fans don't even blink, and the bulb trick just flashes once briefly.

On visual inspection everything looks OK, but after some meter testing it seems the +12V rectifier is blown:

Legs 1 Leg 2 (center): .001 continuous beep, Ω 1.7
Legs 3 Leg 2 (center): .001 continuous beep, Ω 1.7

This +12V rectifier is a STPS40M60CTN which replaced the original MBR20150CTP (max Vrrm = 60 vs 150):

Swapped the MBR20150CTP +12V rectifier for a STPS40M60CTN.

>Expand . . . >Expand . . . >Expand

With 40A it was way overkill for the application. I wonder if the repetitive reverse voltage has killed it.

[Behemot]

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

Fuse probably burned too. You can remove that voltage switcher completely while on 230 V.

[stj]

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

foto's

[amede]

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

Someone changed the psu from 230 to 110 mode while in our country is 240 and i sawone MOV blown I changed it but PSU doesn't work.Help me!

[amede]

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

I changed MOV and connected the green and black wire but still no answer in my PSU

[momaka]

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

It is intentional after all...

I have an Allied 2006 psu with the same asymmetry in bleeding resistors!

Must be a design error then! Because I really don't see any reason for the dis-balance in the voltage over the caps. I bet the voltage across the two caps is slightly different too. Oh DEER!

[goodpsusearch]

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

That's foresight .


If I read the colour codes correctly R1 is 330K (orange/orange/yellow/gold), R2 is 470K (yellow/violet/yellow/gold).

Maybe Deer ran out of 330K resistors half way through assembling it?

It is intentional after all...

I have an Allied 2006 psu with the same asymmetry in bleeding resistors!

R3: 462kohm and R4: 330kohm

And the best part is that it might have impact on the caps. The caps are Koshin 200V 470uF and their capacity is:
481uF (in parallel with 462kohm R3)
465uF (in parallel with 330kohm R4)

I am going to open a new thread for that psu soon.

[TELVM]

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

The stranded 20A Schottky rectifier from the TOOQ has found a new home in the Allied PSU, which came with this anorexic 10A superfast on the +12V rail :

This time the insulating pad was not forgotten and it works, oh Deer!