200W is not the same as 200W

[Rainbow]

See this crap marked as 200W - thin wires, small components and overall "empty" look.

[Rainbow]

Re: 200W is not the same as 200W

And compare with this. Even the fuse is in fuse holder, not soldered to the PCB. The characteristic of these PSUs are non-standard wire colors (e.g. violet instead of orange for 3.3V).

[linuxguru]

Re: 200W is not the same as 200W

The first one is about 90W-150W max. (since the primary caps are 330uF, I'll concede that it may be at the high end of the range), while the second is real (possibly even under-rated). The general thumb rule that I use is that if there are two fair-sized toroids on the secondary and a few large caps (>=2200uF), it's probably correctly rated. If there's only one toroid and small capacitors (1000uF or lower), it's a fake rating. This crap started with the 200W AT PSUs.

[Newbie2]

Re: 200W is not the same as 200W

The first one reminds me of an old generic 250W ATX power supply I used to have in my secondary system. The board, two cheap heatsinks, and weak 80MM cooling fan were the same. The only thing that was different was that it had CapXon caps. That thing I used to have is now dead.

[Chris1992]

Re: 200W is not the same as 200W

My generic ‘300W' that I'm running this sys on is between the two. I'm kicking myself for getting rid of an ancient AT 250W DTK P/S because I could have used it for fan testing.

[Rainbow]

Re: 200W is not the same as 200W

This is the same crap as the first one except it's marked 230W. The failure is the same too. I don't repair crap like this - it's a good source of "C945" TO92 transistors (at least 8 in each) for other PSU repairs - they're used a lot by various PSU manufacturers.
I remember that I found real manufacturer of these PSUs some time ago - and this type was marked as 160W or something like that - but I'm unable to find it again now.

[japlytic]

Re: 200W is not the same as 200W

This topic shows that this deceptive practice (the thread topic is self-explanatory) is apparantely rife.

Any cases on suppliers being caught in this deceptive practice?

[Newbie2]

Re: 200W is not the same as 200W

This is the same crap as the first one except it's marked 230W. The failure is the same too. I don't repair crap like this - it's a good source of "C945" TO92 transistors (at least 8 in each) for other PSU repairs - they're used a lot by various PSU manufacturers.
I remember that I found real manufacturer of these PSUs some time ago - and this type was marked as 160W or something like that - but I'm unable to find it again now.

That thing has Jun Fu caps instead of HEC caps. But, both of them are crappy. I have the same crap in my basement too but it uses CapXon caps and is on the sticker says it's rated for 250W. When it was still alive I put it in an old ATX system that used a very old Pentium 133 processor and it made a loud high-pitched sound that I can't describe some more and the system always restarted and froze. I took that thing out and put in an old Delta 145W ATX PSU and then it worked perfectly. That tells me those things are total crap.

[japlytic]

Re: 200W is not the same as 200W

A search for power supplies with misleading ratings revealed the practices in the below links are rife.

http://www.tomshardware.com/howto/20021021/
http://www.pcpowercooling.com/technology/myths/ (at 50C, a so-called "500W" unit's output was halved).

The message: Only buy from manufacturers who make units with reliable output ratings.

[Mustang]

Re: 200W is not the same as 200W

Here's a pic of a supposed 450W supply that I doubt would even come close before frying. The 2 large caps on the primary side are 470uf . Largest caps on secondary side are 2 1000uf 16v.

[linuxguru]

Re: 200W is not the same as 200W

I'd estimate that it's about 150W-250W, max. From the description of the secondary caps, I'd guess it's at the low end of that range.

[Spacedye69]

Re: 200W is not the same as 200W

Whats the relationship between cap size and power rating? I have a dead ps from PowMax that is rated for 400W. It has 2 330uF/200v on primary side and 2 bulging 2200uF/10v on secondary. All caps are JEE. Luckily, looks like the only thing that poofed was the fuse. Did the bad caps cause the fuse to blow, or too much power usage for crappy ps?

[kc8adu]

Re: 200W is not the same as 200W

Whats the relationship between cap size and power rating? I have a dead ps from PowMax that is rated for 400W. It has 2 330uF/200v on primary side and 2 bulging 2200uF/10v on secondary. All caps are JEE. Luckily, looks like the only thing that poofed was the fuse. Did the bad caps cause the fuse to blow, or too much power usage for crappy ps?

if the fuse blew the choppers are shorted.
powmax is pure crap.aptly named as i see lots of em go pow.
dont waste your time.
these things are worse than junk.
they have no short protection.combine that with the undersized wiring and a short on say +5 you get fire!

[Spacedye69]

Re: 200W is not the same as 200W

Thanks for advice, will toss it in (s)crap pile. What about sizing of caps. Make any difference on output of ps?

[Rainbow]

Re: 200W is not the same as 200W

2x 330uF is used on cheap 200W PSUs - like the one in the first post. The higher power rating, the bigger capacitance should be used. For example, 300W DTK PTP-3007 (the same type as the 200W one in the second post but higher rating) has two 680uF caps on the primary side...

[PeteS in CA]

Re: 200W is not the same as 200W

Re I/P lytics, the output from the bridge rectifier, if unfiltered, would look like an endless line of bactrian camels. The lytics filter this by storing energy during the peaks of the voltage humps and supplying some of that stored energy to the load between the peaks. Thus, the voltage waveform is a sawtooth AC voltage superimposed on a DC level. The amplitude of the sawtooth voltage is determined by the size of the lytic caps and the amount of energy drawn from them between peaks of the power line AC voltage. If the I/P lytics are too small, the voltage to the inverter may be low enough that the PWM cannot fully compensate for the 120Hz (100Hz) ripple - resulting in an elevated 120Hz (100Hz) component in the O/P ripple - or in a brief AC line drop-out, the O/P voltages could briefly drop out of regulation.

On a tangent, the AC I/P current to the circuit described above is basically peaks of high current at the AC voltage peaks, with flatline between the current peaks. When you have lots of computers in a building, those current peaks can clip the AC voltage waveform and also cause high currents in the AC Neutral wire (ideally, if the load on the three phases is balanced, the current in the Neutral wire should be approximately zero), potentially exceeding the capacity of the wire. Power factor correction, passive (large heavy 50Hz/60Hz inductor) or active, is intended to diminish or almost eliminate these problems.

[Spacedye69]

Re: 200W is not the same as 200W

WOW! That answers some questions, yet creates so may more! In a few months I will be enrolling in Electronics w/ Computer Hardware emphasis. Then maybe I will be able to understand the other half of what you said. Thanks.

[arneson]

Re: 200W is not the same as 200W

Pete, I do have questions about the load balancing you mentioned, but more in a home environment.
This is off topic but If I've added a substantialy heavy draw to my breaker panel do I understand I may have high current on the nuetral buss?

Don't let out that I wired my own hot tub.

[AK0R]

Re: 200W is not the same as 200W

Is it powered from 110 or 220? If 220, the load will be automatically balanced between the two phases. The problem comes if you load one of the two phases coming into the house more than the other, since the neutral is shared between the two.

[arneson]

Re: 200W is not the same as 200W

Thank you, good simple explanation.
This is a small simple hot tub and runs very efficiantly on 110vac.
By far one of the best things I've ever had.