Rebuilding Rosewill 350W

[370forlife]

Re: Rebuilding Rosewill 350W

My next project coming up: Leadman LP6100C. Also, I just rebuilt a sunpro-raidmax 450W. The tiniest secondary capacitors I have ever seen. This psu is used very little as a backup psu by my friend, so it got the leftover teapo caps, 2 X caps, 2 Y caps, better filtering coil, Capxon 470uf, 250v primaries. One thing we didn't do is put a bridge rectifier in it, as I don't have one that will fit. Voltages checked out very well on it, starting right at 12.05, 5.03, and 3.41.

I have a lot of leftover secondary and primary silicon from some gutted psu's, I wonder if I could add those to improve the capacity of it.

[everell]

Re: Rebuilding Rosewill 350W

OK.......here is the Raptor 400 watt L&C with two transistor 5vsb removed and piggyback board with DM311 5vsb installed. No load voltage set to 5.01 volts. Using a load resistor of 4.75 ohms, the voltage reading was 5.94 volts. Good results for a one amp test.

The modification required one pc board trace cut. Photo included. And schematics.

[370forlife]

Re: Rebuilding Rosewill 350W

5.94 volts...wouldn't that blow up your chipset?

And why did your avatar suddenly get so tiny?

Also do you have any idea what goes in that spot with the two jumper wires across it?

[momaka]

Re: Rebuilding Rosewill 350W

Also do you have any idea what goes in that spot with the two jumper wires across it?

Are you talking about the in the primary side next to the bridge rectifier?
If so, it looks like space for an extra input filtering choke/coil.

[Toasty]

Re: Rebuilding Rosewill 350W

>>No load voltage set to 5.01 volts. Using a load resistor of 4.75 ohms, the voltage reading was 5.94 volts. Good results for a one amp test.<<

????

Happy fingers... 4.94 volts

OR

Dyslexia... 4.95 volts

[momaka]

Re: Rebuilding Rosewill 350W

Happy fingers... 4.94 volts
OR
Dyslexia... 4.95 volts

By the way, I just noticed that in everell's new desing, the main 5vsb transistor is removed and only DM311 is powering the 5vsb. Wouldn't that make DM311 overheat, though?
I hope I'm not asking a dumb question.

[yanz]

Re: Rebuilding Rosewill 350W

i like it, everell. it looks nice and simple.

[370forlife]

Re: Rebuilding Rosewill 350W

Are you talking about the in the primary side next to the bridge rectifier?
If so, it looks like space for an extra input filtering choke/coil.

That would make sense, but I wouldn't want to put one there and have it 'splode or do something else on me.

[Krankshaft]

Re: Rebuilding Rosewill 350W

That Chinamart PSUs got some 'splodin to do .

Couldn't resist with the old reference.

[everell]

Re: Rebuilding Rosewill 350W

Now, now ...... you shouldn't pick on an old fart. Couple of weeks, on September 2, I will be 61. Don't feel 61, except for occasional "happy fingers" and "dyslexia"! And ratdude, just for your information, mother still tells me to "grow up". Mothers just don't quit.

It was a little late for me when I posted the info on the mods for the Raptor L&C power supply. What was intended was .... I set the no load voltage at 5.01 volts. With a 4.75 ohm load, it measured 4.94 volts.

Why a load resistance of 4.75 ohms? The ATX specification says the 5vsb should be 5 volts plus or minus five per cent. That would be .25 volts either direction. Since a load resistor should reduce the voltage, I figured that this circuit should be capable of producing one amp at the lowest permissible voltage, which would be 4.75 volts. Using ohm's law, I simply calculated the needed load resistor based on 4.75 volts at one amp. I found a 6 ohm 50 watt resistor. I paralleled a 25 ohm 10 watt resistor across it. Then to tweak it I paralleled a 470 ohm 2 watt resistor across the other two. Resistance came out close enough. At 4.94 volts, that would be a little more than one amp, but was close enough for me.

The DM311 chip has a power FET inside. Therefore, a power transistor is not needed for the circuit. Check out the data sheet on DM311. It is very impressive.

I did not understand which jumper wires you were asking about. Perhaps you can add some details to your question.

Toasty - this is the circuit I want to try on the Powerman PSU. Still haven't found a 5vsb transformer.

The mama bird on the forklift is now quite busy. The eggs hatched, and the little baby birds wait patiently while mama flies back and forth with food. Busy birdie!

[370forlife]

Re: Rebuilding Rosewill 350W

I did not understand which jumper wires you were asking about. Perhaps you can add some details to your question.

The jumper wire between the bridge rectifier and the filtering coil on your psu. Mine has that exact same spot, I don't know what would go there.

[everell]

Re: Rebuilding Rosewill 350W

The markings on my pc board are L1, L2, and C3. My line filter coil is labeled LF1, and the capacitor installed is labeled CX1. I am assuming that the manufacturer could use the LF1 position as on my board, or use the L1 or L2 position for a toroid coil. The C3 is probably a capacitor option, either to add another capacitor, or to use with a toroid coil when used.

My pc board has (on the output side) the option of using either a 16 pin chip or a 20 pin chip for the pwm/supervisor. I see some other places for parts not installed and some unused parts jumpered. Again, I think this is a matter of options the manufacturer uses depending on wattage and quality.

I am NOT an engineer, but for a 200 watt or so psu, I don't think you will gain much by adding additional line filtering.

In my opinion, the most gain comes from changing the input and output filter capacitors, modifying the 5vsb circuit, and adding the line filter you have already added.

My 5vsb modification has been implemented on the Raptor L&C 400 watt? unit, a SeaSonic 250 watt unit, and a Bestec 250 watt mobo killer (former mobo killer!). It works well on all of them.

[larrymoencurly]

Re: Rebuilding Rosewill 350W

My next project coming up: Leadman LP6100C.

I have one with the big heatsinks, and in addition to its bigger caps failing, the 1uF - 10uF ones go bad as well, and I think they receive 50V spikes.

[370forlife]

Re: Rebuilding Rosewill 350W

I was looking at getting a LP6100C which is the 300W version, and surprisingly the LP6100D which is suppose to be a 400W or so will actually run its ratings. But, not much work needs to go into one except caps and a bridge rectifier. I'm working on getting a old YueLin power supply from a friend to tinker with. This one ran as a supplementary psu powering 3 gtx260's in his computer by itself.

[everell]

Re: Rebuilding Rosewill 350W

Are you saying you are "going to buy" a LP6100C? I have a LP6100 (by Extreme) and the transformers inside are even SMALLER then the L&C power supply. On the other hand, the Bestec which gets the bad rap has larger transformers than both LP6100 and L&C. If you have not yet purchased the LP6100C, perhaps it would be going in the wrong direction! Even a Bestec can be improved - it just needs work on the 5vsb.

If you already have the LP6100C, you can compare it with my circuit board.

[momaka]

Re: Rebuilding Rosewill 350W

I was looking at getting a LP6100C which is the 300W version, and surprisingly the LP6100D which is suppose to be a 400W or so will actually run its ratings.

Only worth it if you can find an older LP6100 model. The newer ones are built just like all the other regular gutless PSUs with small transformers and tiny primary switchers.

I have one with the big heatsinks, and in addition to its bigger caps failing, the 1uF - 10uF ones go bad as well, and I think they receive 50V spikes.

Have you scope the voltage on those caps? Would be interesting to see if the caps really did get 50v spikes. Reason I'm wondering is because I might recap mine as well.

everell: I think the Powmax you have is not a LP6100 but rather a LP7700 variant (as indicated by the transformers). I believe LP6100 has a different design using two 8-pin ICs: a 3842/3843 as the PWM controller and another 8-pin IC responsible for monitoring the voltages on the secondary side (not sure if it's a supervisory chip like the TPS3510P or a dual-voltage comparator like the DBL393, though). Instead of having an isolation transformer, it has 3 optocouplers. The silkscreen for the input filtering is also different.

[370forlife]

Re: Rebuilding Rosewill 350W

I have a leadman lp-8860 and they are identified by the transformer's markings. It uses the same 5vsb transformer as the lp6100 though, as that is marked by lp6100.

The primary transformer is even labeleb as "250W" on the side, even though it was marketed as a 650W. He he.

Real lp6100's have tall heatsinks and actual full input filters.

[everell]

Re: Rebuilding Rosewill 350W

I have an Extreme LP-6100D 400 watt psu - switching transformer marked 7700

Powmax LP-7700D 350 watt psu - switching transformer marked 7700

Powmax LP-8800D 400 watt psu - switching transformer marked 8100

All have the tiny transformers - I don't think any will handle full load as specified on label.

Each of the three circuit boards is different - and use a different chipset. I think they are throwing just about anything in the box and sticking a label on for whatever the customer orders. At this point I don't believe that ordering a LP-6100C will actually get you a LP-6100C. Perhaps a box with a label that says LP-6100C, but what is inside?

Old Chinese proverb say "You get what you pay for ..... if you are lucky!"

[yanz]

Re: Rebuilding Rosewill 350W

@370forlife

Hihihi.. Dejavu.. I knew when i saw your pics i have one in my warehouse that looks exacly like your Rosewill. But this one is called Simbadda SZ-430WP4, claimed for 430W.

Caps in the secondary is all AsiaX TMX.

The cables are unbelievably of 18 AWG except for molex wires (20 AWG).

There's a plastic sheet under PCB.

This PSU was from a client that want an upgrade for his entire system. I change the old PSU with a Seventeam 300W (or 250W, i dont remember).

I would use this Simbadda PSU for other project if only i don't have a pile of Seasonic 300W.

I'll recap it and use it for experiment, maybe for changing the 5vsb regulator like everell did. It's really interesting.

Oh, note that it has 2x 12V rails. But, really?

[yanz]

Re: Rebuilding Rosewill 350W

@everell

tell me about it.. cheap psu with tiny transformer but claimed for 400W ++

meh!


Hipro 300W (big) vs Ersys 450W (small) :