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Old 08-04-2021, 08:34 PM   #3141
Togepi
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Default Re: Power supply build quality pictorial. part 2

Hello,

here I have a Cooler Master power supply MasterLite 600Watt. It is new and unused. All capacitors in the device appear to be from CapXon. I don't know if this is good or bad now. The device is new and unused. I would have been interested in who the right manufacturer of the power supply is. Can someone see that from the pictures?





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Old 08-05-2021, 04:23 PM   #3142
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Default Re: Power supply build quality pictorial. part 2

CapXon is a brand not respected here. However it looks like some of the output capacitors are polymer types.

The power supply puzzles me. It is rated as simple "80 Plus", but those heatsinks look insufficient for a 600W power supply. The main transformer also looks odd. My best guess is that the switch frequency is somewhat high, and phase modulation is used rather than pulse width modulation. But if that's the case, I would think it would be rated as at least "Bronze" or "Silver".
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Old 11-22-2021, 06:27 AM   #3143
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Default Re: Power supply build quality pictorial. part 2

A saved an old ATX power supply from recycling last week.
The casing is damaged, has dents, a broken fan but the insides are intact.

EverPower brand with a 235W Channel Well Tech guts from 1997.


There is a seperate transformer attached to the casing that looked like passive PFC at first but it isn't. The 5V standby has 100mA current capability and it is generated using this trafo, rectifier and a 7905 regulator. I haven't seen this "cheap" method before.
The standby trafo has primary winding taped for both 110V and 230V.


The unit has ok EMI filtering, 4 Amp bridge rectifier, 330uF Matsushita input capacitors.
It's a half bridge topology with two 13007 BJTs controlled by KA7500 pwm.



A 339 comparator is used to supervise the output voltages. There is also a seperate fan controller circuit.

https://www.badcaps.net/forum/attach...5&d=1637581493


The 3.3V rail is also unusual. No mag amp circuit.
A UTC34063 is set up in step down configuration to make the 3.3V work.


Secondary electrolitic capacitors are all Fuhjyuus so that's bad.


I've cleaned and tested the psu. Turns on, voltages are a bit low-ish and fluctuating, ripple is probaly high also. Kind of unusual early ATX unit.
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Old 11-22-2021, 12:03 PM   #3144
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Default Re: Power supply build quality pictorial. part 2

What a fascinating design! I want one just for the sheer novelty.
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Old 11-23-2021, 12:55 PM   #3145
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Default Re: Power supply build quality pictorial. part 2

Quote:
There is a seperate transformer attached to the casing that looked like passive PFC at first but it isn't. The 5V standby has 100mA current capability and it is generated using this trafo, rectifier and a 7905 regulator. I haven't seen this "cheap" method before.
The current rating for the +5SB is just .1A, some the effect on efficiency is minimal. A 50/60 Hz transformer, recifiers, and 7805 3T regulator might have been cheaper than a flyback switching regulator circuit. .1A was pretty minimal for that era. I would expect 1.0-1.5A.

A TL494 clone and MJE13007 clone BJTs would easily have been adequate for the ATX spec of that era and the 235W rating; the heatsinks were OK, if not spectacular heavy metal. Looks like the PCB was laid out to allow higher power switch transistors and output transformer. The 330uF input caps might have been marginal for hold-up time. The fluctuating output voltages and high ripple could be due to the 24 year old output caps having increased in impedance. Replacing the F-yus with Nichicon PJ or PW or NCC LXV or LXZ series caps (which were in common use in the late 1990s) might result in better performance.
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Old 11-23-2021, 02:44 PM   #3146
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Default Re: Power supply build quality pictorial. part 2

Earliest ATX 1.0 spec indeed only specced only 100mA so I suspect they may have built to spec though whether or not they exceeded or not is another question. My question is why is it using an overspecced and odd 7905 negative rail regulator when a cheaper 78L05 or 78M05 would do? Incidentally I'd not call this "cheap" but rather "old, inefficient" ... those transformers are not cheap to source or ship in volume...

I found a couple of old Fuhjyyu's in some device that predates the old Antec Smartpower Fuhjyyu plague and they actually are still okay... Not sure if's just that one period with the scandal that they produced so many poppers...
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Old 11-24-2021, 04:17 AM   #3147
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Default Re: Power supply build quality pictorial. part 2

Quote:
Originally Posted by eccerr0r View Post
My question is why is it using an overspecced and odd 7905 negative rail regulator when a cheaper 78L05 or 78M05 would do?
Sorry, 7905 was a typo. It is a L7805C positive voltage regulator. It is visable on the pictures. The ic has that simple piece of metal screwed on for heatsinking. The pcb silkscreening suggests a TO-92 device instead of TO220 that is crammed in there.
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Old 11-29-2021, 07:24 PM   #3148
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Default Re: Power supply build quality pictorial. part 2

Quote:
Originally Posted by eccerr0r View Post

I found a couple of old Fuhjyyu's in some device that predates the old Antec Smartpower Fuhjyyu plague and they actually are still okay... Not sure if's just that one period with the scandal that they produced so many poppers...
The reason those caps failed a lot in Antec psus has to do with how hot they got due to the design of the parts location inside and also the fact that the fan controller was configured very aggressively to be silent. And the fact that their efficiency was nowhere close to what we have today didn't help either (~74%)
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Old 11-29-2021, 10:26 PM   #3149
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Default Re: Power supply build quality pictorial. part 2

I'd imagine back when these Fuhjyyus were installed it was before the Antec era and efficiencies were even lower...

We'll see I suppose, so far they're surviving the time.
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