$20 "500W" PSU From MicroCenter, how bad can it be?

[dmill89]

Re: $20 "500W" PSU From MicroCenter, how bad can it be?

looks like 200W... if that much...

It couldn't even do the lower 137W in spec (granted that is an ancient PSU tester so it was very 3.3V/5V heavy, but that is also an ancient PSU design so it should actually handle that better than a 12V heavy load of a modern system), so as far as meeting ATX specs it looks like a <100W unit, granted it could probably handle 200W without blowing up, but it would be feeding your components a ton of ripple that would slowly destroy them.

At the higher 257W load (the built in 137W from the PSU tester + 2 60W electronic loads on the 12V rail) it really did feel like it was on the verge of blowing up with the smell it was making and the amount of hot air coming off the exhaust.

[cashkennedy]

Re: $20 "500W" PSU From MicroCenter, how bad can it be?

I don't blame them with all the idiots I hear still insisting on 750-850w power supplies for systems with midrange processors (ryzen 3600x), and upper mid video cards (gtx 1660). Those idiots (which seem to be the majority of people building computers) usually think 500w wouldn't be enough for any system with a discrete video card.

[dmill89]

Re: $20 "500W" PSU From MicroCenter, how bad can it be?

Keep on seeing that silly skinny extruded T heatsink... powmax?

looks like 200W... if that much...

KA7500/TL494 or what custom chip does it use?

UTC7520D (looks like a knock off of a Weltrend WT7520):

[eccerr0r]

Re: $20 "500W" PSU From MicroCenter, how bad can it be?

Keep on seeing that silly skinny extruded T heatsink... powmax?

looks like 200W... if that much...

KA7500/TL494 or what custom chip does it use?

[dmill89]

Here we have the Solid Gear (MicroCenter House Brand) Basix SDGR-500BX "500W" PSU, one of their cheapest ATX power supplies selling for a whopping $19.99,


lets take a look at how good/bad it is:

Box, pretty basic packaging:


It claims 26A on the 12V rail and 22A ea. on the 3.3V and 5V rail.



The unit itself is a pretty basic grey box as expected at this price point:


No APFC (not surprising at this price point):



Label claims the same as the box (at least the lies are consistent).




Lets take a look inside. Oh boy, this isn't good:




Primary has 2X "Rubycon" PX 220uf 250v caps (these caps look really old and dirty so they may be "recycled"), a pair of 13007 (8A 400V) transistors for the primary and a C3150 (50W 800V) on the standby. The input "filtering" (if you could call it that) consists of 1 x-cap and 2 y-caps directly on the mains connector. It is also using the 4 diodes treatment for the bridge rectifier.



On the secondary side we have a Mospec F16C20C (16A 200V) ultra-fast diode on the 12V rail (hmm didn't the label claim 26A??), and MCC MBR2045CT (20A 45V) Schottky diodes for the 5V and 3.3V rails (and the label claimed 22A for these).


Secondary Caps as follows:

3x Jayi 1000uf 16v
2x ZTLCon 1000uf 10v
2x Jwco 470uf 16v


Bottom of the board, not terrible for a cheap unit:


Lets see how it handles some load:

Starting with the 137.6W load from my Seasonic power supply tester

Note: the oscilloscope is set to the 100mV per division scale

12V:




Voltage at 12.586V which is in spec, but the 250mV ripple isn't, so this thing fails even with a fairly light load.

5V:




5.0335V, but 225 mV ripple again out of spec.


3.3V



3.1099V and 200 mV ripple out of spec on both counts here.

Power draw:


178W for a 77% efficiency.

Now lets add an additional 10A on the 12V rail to bump it up to 257.6W:

12V:



12.363V and over 300 mV ripple (and look at how ugly the ripple in the +/-100mV range is ).

5V:



5.082V with around 275 mV ripple


3.3V



3.1206V with around 225 mV ripple

Power draw:


338W for a 76% efficiency.


Well, it didn't blow up, though it did start to smell "bad" (like hot melt glue) in the second test so I doubt it would last very long under that load. The ripple is downright ugly though even under the lighter load so I wouldn't use this thing on any PC I cared about (or any PC for that matter).