Found a brand new Comp USA PSU

[Pentium4]

Re: Found a brand new Comp USA PSU

TO-247/TO-3P packages dissipate heat better because they cover more surface area of the heatsink. That being said, depending on the type of heatsink used and how the rest of the PSU is designed, that might not be a problem. Some 80+ PSUs have gotten away with using TO-220 switchers without the metal tab so I'm not contesting what you said either.

Leadmans are indeed garbage, in fact they're some of the worst junk out there so unless you really want to refurbish it I think it merits scrapping.

Honestly I think that this is better than some of the newer flyback converters that Leadman has been making with those T heatsinks that look like they were made from beer cans, and ZERO filtering caps on some of the major rails, completely unacceptable! At least this would be usable in a low end 5V heavy design back in the day (Although those JEE caps and the transistor with no heatsink would die quickly)

[Wester547]

Re: Found a brand new Comp USA PSU

IMHO, the fact that there is a TO-220 device there doesn't mean a thing, depending on how the PSU is designed, it could be perfectly fine

TO-247/TO-3P packages dissipate heat better because they cover more surface area of the heatsink. That being said, depending on the type of heatsink used and how the rest of the PSU is designed, that might not be a problem. Some 80+ PSUs have gotten away with using TO-220 switchers without the metal tab so I'm not contesting what you said either.

Leadmans are indeed garbage, in fact they're some of the worst junk out there so unless you really want to refurbish it I think it merits scrapping.

[Pentium4]

Re: Found a brand new Comp USA PSU

Wasn't there a Leadman that dumped primary voltage into a motherboard a while back? Poor transformer construction or random wire clippings? I would've loved to "autopsy" that one!

Really?! I would love to autopsy that thing too

IMHO, the fact that there is a TO-220 device there doesn't mean a thing, depending on how the PSU is designed, it could be perfectly fine

I bet the 5vsb transistor will fry before the capacitors do, that transistor probably has to dissipate around 2-4 watts! With no heatsink!

You're right especially since it has that good sized heat sink all to itself. If I decide to do anything, I will add a heatsink to it, even a tiny one would help it out quite a bit, those old two transistor designs seem to create a lot of heat!

Yes, the UC3843 is the controller, and that transistor sitting there without a heatsink is indeed for the two transistor 5vsb circuit. It looks like there is a separate 8 pin IC for the protections on the secondary. Most likely 12v and 5v OVP and OCP, and SCP.

If you don't want it, I would gladly take it off of your hands. I, for whatever reasons, like to keep some examples of some of these smaller manufacturers units. Leadman units aren't that rare, but these older units are a bit harder to find.

I couldn't find much but that IC reads ST1412A. I would be surprised if it had OCP.

I agree, these small manufacturer PSU's are pretty cool because they aren't common and when I saw this one in the packaging for $7 I couldn't pass it up but if I decide to get rid of it you will be the first person I contact!

[370forlife]

Re: Found a brand new Comp USA PSU

So I'm confused, the UC3843 doesn't generate the 5VSB, so that transistor just sitting there with no heatsink is? Okay that makes more sense not sure why I didn't catch that

I know or maybe it was stored in a hot place for a while and just bulged

I'm not sure yet if I want to just keep it as memorabilia or fix it up. The fan may just need some oil, I haven't checked it yet

Yes, the UC3843 is the controller, and that transistor sitting there without a heatsink is indeed for the two transistor 5vsb circuit. It looks like there is a separate 8 pin IC for the protections on the secondary. Most likely 12v and 5v OVP and OCP, and SCP.

If you don't want it, I would gladly take it off of your hands. I, for whatever reasons, like to keep some examples of some of these smaller manufacturers units. Leadman units aren't that rare, but these older units are a bit harder to find.

[ben7]

Re: Found a brand new Comp USA PSU

IMHO, the fact that there is a TO-220 device there doesn't mean a thing, depending on how the PSU is designed, it could be perfectly fine

I bet the 5vsb transistor will fry before the capacitors do, that transistor probably has to dissipate around 2-4 watts! With no heatsink!

[kaboom]

Re: Found a brand new Comp USA PSU

Yeah I did notice all the misplaced components. It is a Leadman afterall

225? Seems a little low for the size of it.

Yeah instead of a 247 they just bent the legs to fit ha ha

Now that I've looked a little better at it, you might be able to get 300 out of it. I'm used to the smaller transformer that Pow (to the) Maxes usually have.

It is a Leadman afterall

Wasn't there a Leadman that dumped primary voltage into a motherboard a while back? Poor transformer construction or random wire clippings? I would've loved to "autopsy" that one!

[Pentium4]

Re: Found a brand new Comp USA PSU

Yeah I did notice all the misplaced components. It is a Leadman afterall

225? Seems a little low for the size of it.

Yeah instead of a 247 they just bent the legs to fit ha ha

[kaboom]

Re: Found a brand new Comp USA PSU

I'm not sure yet if I want to just keep it as memorabilia or fix it up.

If you want...

It is a hacked together heap, though. Look at all the "misplaced" components- doubled up resistors, parts not placed according to their silkscreen markings, a 4148 diode going "cockeyed" from a jumper to resistor, etc.

Oh "JEE," what can the matter be?

Also, that transformer will not be happy over ~225W.

Nice TO-220 MOSFET where a '247 should be! No lock washer, either.

MOSFET for 5VSB/AUX not heatsinked, the caps next to it will dry out. 5VSB becomes 15VSB!

I'll bet the leads to the 4 pin CPU connector are #20, not #18.

1. The 5vsb IS the two-transistor type. That chip looks like a UC3843, for the main smps.

Correct and correct.

2. LOL at the bulged capacitor. It MIGHT be possible that the psu was powered on for quality check testing at the factory (just to see if it works before shipping it)

It probably swelled up all by itself.

3. If your gonna fix up this sucker for fun, replace the following:

• 5vsb circuit with the 5vsb mod
• Crappy capacitors
• Crappy fan
  
• Entire power supply

[Pentium4]

Re: Found a brand new Comp USA PSU

So I'm confused, the UC3843 doesn't generate the 5VSB, so that transistor just sitting there with no heatsink is? Okay that makes more sense not sure why I didn't catch that

I know or maybe it was stored in a hot place for a while and just bulged

I'm not sure yet if I want to just keep it as memorabilia or fix it up. The fan may just need some oil, I haven't checked it yet

[ben7]

Re: Found a brand new Comp USA PSU

1. The 5vsb IS the two-transistor type. That chip looks like a UC3843, for the main smps.

2. LOL at the bulged capacitor. It MIGHT be possible that the psu was powered on for quality check testing at the factory (just to see if it works before shipping it)

3. If your gonna fix up this sucker for fun, replace the following:

• 5vsb circuit with the 5vsb mod
• Crappy capacitors
• Crappy fan

[Sparkey55]

Re: Found a brand new Comp USA PSU

The last POWMAX that I used in 2004 lived up to its name in flames out the back of my computer.

[Pentium4]

One of those old Leadman LP6100's. Still in the packaging and still smells new from the factory, made in Feb, 2002! My initial thoughts before opening it and seeing the POWMAX fan at the rear: After opening it....not as bad as I anticipated

It's got a full EMI filter, although no MOV's. Shame on you Leadman. It's got four good sized 3A diodes with room for airflow, 680uF JEE input caps, and a single Toshiba K2996 10A MOSFET, not bad....it doesn't use a 2 transistor design for 5VSB which is nice. Decent sized transformer for a 300W. That controller IC next to the primary heatsink is an AP3843B. The 3.3V rail is missing its inductor. Very nice heatsinks, and they feel very sturdy

Secondary rectifiers: SBL2040CT 20A schottky for 3.3V, SBL3040PT 30A schottky for 5V, and an FET16BT 16A Ultra fast rectifier for 12V. Not bad considering what the label says... Can't find any info on the other 8 pin IC on the secondary.

All the caps are JEE except three little 1uF 50V caps are JPCE-TUR and one of the JPCE caps is a value I've never seen before! 4.7uF 10V, C30, the one with the cross vent next to the optocouplers (datasheet: http://www.datasheetarchive.com/cosm...datasheet.html )

The POWMAX fan barely spins and has no rock to it

Edit: Worth noting that the JEE cap on the -12V rail is bulging despite never being used