iCute ATX-400W/P4 Refresh with Questions

**ckrtech** · 08-29-2016, 02:08 AM

Re: iCute ATX-400W/P4 Refresh with Questions

Reserved

**stj** · 08-29-2016, 02:31 AM

Re: iCute ATX-400W/P4 Refresh with Questions

i meter the large caps - if the uf looks o.k. then they stay.

**ChaosLegionnaire** · 08-29-2016, 12:04 PM

Re: iCute ATX-400W/P4 Refresh with Questions

i suggest u not use the psu for anything critical or anything u cant afford to lose even after recapping. these icute psus are infamous here in my side of the world for being hand grenades. they lack the proper or working ocp, ovp and opp protection. if anything goes wrong, it will most likely fry your entire system, hard drive included. buyer beware lol, tho i should have informed u before buying keke~

now u know why it was going for so cheap lol

**ckrtech** · 08-29-2016, 05:40 PM

Re: iCute ATX-400W/P4 Refresh with Questions

Sounds like I just don't even want to bother with it, then? That's too bad.

**ckrtech** · 08-30-2016, 10:10 PM

Re: iCute ATX-400W/P4 Refresh with Questions

So what criteria/components do you guys use to determine if a power supply is worth recapping or not?

**momaka** · 09-01-2016, 12:43 AM

Re: iCute ATX-400W/P4 Refresh with Questions

Originally posted by ckrtech

Sounds like I just don't even want to bother with it, then? That's too bad.

Well, you *could* bother with it if you don't mind getting all of the extra parts that are missing from this PSU, besides doing a proper recap.

Normally, I don't suggest anyone (anymore) fix up PSUs that appear to be of really low-quality like this one, unless it is for learning purposes. But this particular PSU is based on an old Channel Well (CWT ISO line) half-bridge design that isn't half bad

actually. Should be very similar to this PSU:
https://www.badcaps.net/forum/showthread.php?t=39370

So if you do decide to fix it up (not just as a learning experience, but also to use in a low-power computer), this PSU won't be that bad if you put all of the necessary parts in it. Don't expect miracles though - at best, you will end up with an "okay" 200 Watt power supply (which would basically be enough for a low-end Core 2 Duo PC with onboard/low-power video card or similar).

The things that you would really need to do is:
-- upgrade all of the output capacitors on the major rails with the following capacities:
2x 2200 uF (or higher) caps for the 3.3V rail
2x 2200 uF (or higher) caps for the 5V rail
2x 1200 uF (or higher) caps for the 12V rail or a single 2200 uF (or higher) cap
2x 1000 uF caps for the 5VSB rail
One 470-1000 uF cap for the -12V rail

-- install bigger schottky rectifiers on the secondary:
30 Amp 45V or higher for the 3.3V and 5V rails each, 16 Amp 60V or higher for the 12V rail (if you intend to power any PCs that require a 4-pin CPU power connector).

-- install all of the missing input/primary side EMI/RFI filtering components. Typically, that consists of at least one X-rated safety cap, two Y-rated safety caps, and a common-mode choke (tip: these parts can be readily found on the boards of many CRT TVs, so if you see one busted at your local dump or on the street, just grab its board).

Originally posted by ckrtech

So what criteria/components do you guys use to determine if a power supply is worth recapping or not?

Big capacitors on the output of the power supply (i.e. the caps closer to the output wires) and adequately-rated rectifiers on the secondary side (typically 30 Amp schottky diodes for the 3.3V and 5V rails, and at least a 16 Amp rectifier for the 12V rail).

Run away if:
- input EMI/RFI filtering is missing (easily the #1 indication of a low-quality PSU)
- caps on the output appear tiny
- no PI coils between the output caps or the PI coils replaced with jumpers
- very small main transformer

**ckrtech** · 09-01-2016, 01:41 AM

Re: iCute ATX-400W/P4 Refresh with Questions

momaka - I can't thank you enough for providing a detailed response like this one. I would like to jump into the post you linked as well as doing some more reading on my own, however I thought perhaps I would mention a few things regarding application for this power supply (in addition to using it as a learning experience) to see if the task is useful for more than learning alone -

1: It would be (and was in the process of being) used to power an Asus K8V-X SE mobo with Sempron CPU (early-mid 2000s mobo with 4 pin CPU connector) + 1 hard drive + 1 CD-ROM drive

Plus...

Used as a test bench to test several PCI and early AGP era video cards. At that point in time, I believe I was using something closer to 400 watts on my personal rig - most likely my last Antec prior to moving to Corsair.

That 200 watt ultimate rating is rather disappointing, but it seems like maybe it would still be OK...<wince of uncertainty>...?

2: I have a few other candidates (see attachment) - I haven't opened the orange labels (intent was to use them with AT convertor for something like a 486 or 386 assuming they don't look like bombs when I open them up - no brand name unless i overlooked it). I did open the L&C LCA300-ATX, and it looks absolutely terrible inside as far as the caps are concerned. Interestingly, it appears you made a comparison to a Deer PSU that goodpsusearch found and a sad L&C LC-B300ATX in this thread - https://www.badcaps.net/forum/showth...24673&p=291852. I noticed it while searching the forum for details on the sad power supplies that I happened upon.

If you think rebuilding the L&C might be a better exercise, I can go that direction instead. The L&C claims 300 watts while the iCute claims 400.

I do find myself wishing I had random junk parts available (such as a CRT TV board as you mentioned) so I wouldn't have to order everything from digikey. Wondering how much this iCute would ultimately run me.

....

Attached Files

**momaka** · 09-01-2016, 11:26 AM

Re: iCute ATX-400W/P4 Refresh with Questions

Originally posted by ckrtech

... however I thought perhaps I would mention a few things regarding application for this power supply (in addition to using it as a learning experience) to see if the task is useful for more than learning alone -

1: It would be (and was in the process of being) used to power an Asus K8V-X SE mobo with Sempron CPU (early-mid 2000s mobo with 4 pin CPU connector) + 1 hard drive + 1 CD-ROM drive

Plus...

Used as a test bench to test several PCI and early AGP era video cards. At that point in time, I believe I was using something closer to 400 watts on my personal rig - most likely my last Antec prior to moving to Corsair.

An early/mid-2000s Sempron 64 like that won't use more than 80 Watts at maximum load. Heck, even the higher-end Athlon 64 (single core) chips like the 4000+ won't use more than 100 Watts, if even that. Northbridge normally uses 10-15 Watts maximum, and RAM another 10 Watts at worst. A hard drive will take 20 Watts maximum, typically during during spin-up / boot, and much less once it's up and running (maybe 10 Watts at most). CD/DVD/BR drive: Again, another 20 Watts maximum (most power draw occurs when the CD/DVD in the drive is being spun).

So a system like the above won't really use more than 150 Watts of DC power. In fact, based on similar PCs I've set up, a system like that is more likely to use around 60-70 Watts in idle mode (Windows desktop) and 100-120 Watts under maximum load (absolute worst case).

You can make a very good estimate of how much power your PC will use if you know the CPU and GPU TDP (TDP = Thermal Design Power).
To find out a CPU's TDP, I use www.cpu-world.com.
For example, here is a link for the specs of a typical 3 GHz Pentium 4 Prescott HT for socket 478.
http://www.cpu-world.com/CPUs/Pentiu...6PG3000E).html
As per the listed data, TDP = 89 Watts, with the minimum power draw at 54 Watts (system idle), and maximum at 100 Watts.
For GPUs, I typically look up either Xbit Labs reviews or see if Wikipedia has any info.

Originally posted by ckrtech

That 200 watt ultimate rating is rather disappointing, but it seems like maybe it would still be OK...<wince of uncertainty>...?

Yes.
200 Watts of DC power is actually quite a lot. Unfortunately, much of the hype nowadays will have you believe that you need a 500 Watts power supply minimum to power anything. However, the fact is that most CPUs are usually rated for 60-80 Watts TDP (even most of the modern ones). And because most of the power draw for any PC comes from the CPU and GPU, these are the items you really need to focus on. The only exception is when you have more than 4 HDDs, especially 10k/15k RPM sever HDDs - at that point, you need to start minding their power draw too, besides the CPU and GPU.

That said, the next thing to consider is the age of the PC you will be powering: many early and some mid-2000s motherboards relied on the PSU's 5V rail to power the CPU (like Pentium II, Pentium 3, and Athlon XP, as well as the occasional Pentium 4), whereas anything after that pretty much started to use the PSU's 12V rail (evident by the 4-pin CPU power connector).

So for PCs that use power the CPU from the 5V rail, you will want a PSU with a strong 5V rail - typically rated for 20 Amps minimum. And for a newer PC that draws power from the 12V rail, the PSU should be capable of at least 10 Amps on its 12V rail.

With that in mind, the iCute PSU you have should be capable of power both types of systems if you have adequate output rectifiers. Also, when I said that PSU will do 200 Watts max, I was being very conservative. Cheap PSUs like that will actually be able to do up to 250 Watts. But when they get close to or above 300 Watts, they tend to blow up parts. So that's why I rather give out a conservative rating.

But even 200 Watts is more than enough power. I've used a 200 Watt Bestec PSU (ATX-1956D) to power a 2.66 GHz Pentium 4 Northwood (a 67 Watt TDP CPU) in a Dell OptiPlex 270 motherboard. Even had a Radeon 9700 video card in the AGP slot at one point (which was a mid/high range video card for its time), so that another 30-40 Watts added. Under maximum load, that PC probably drew around 120-140 Watts. But my PSU voltage were rock-stable and the PSU barely produced any heat - an indication that it wasn't stressed at all.

So you can be assured that your iCute PSU would be okay for testing older hardware like the above.

Originally posted by ckrtech

2: I have a few other candidates (see attachment)

The orange label ones claim the same power output, but they are different models. LP-6100b is very VERY likely a PowMax/Leadman PSU (espceically since I see an E107407 UL number), and even when they look good inside, they are still pretty mediocre-performing PSUs at best. If you are lucky, that LP-6100b might look something like this:
https://www.badcaps.net/forum/showthread.php?t=51374
^ I've had that PSU power my first "own" computer (1.4 GHz Duron Applebred, 256 MB of RAM, two 20 GB HDDs, and two CD drives) for about 2-3 years before the caps on its outputs went bad and I started getting boot issues. It still "works" to this day and I do plan to fix it. Just not sure if I will use it in anything remotely power-hungry, though.

As for the other "orange label" PSU with the HP-7700 model number - that one doesn't ring any bells in my head, so you would have to post some pictures of it for us to see inside.

Originally posted by ckrtech

I did open the L&C LCA300-ATX, and it looks absolutely terrible inside as far as the caps are concerned. Interestingly, it appears you made a comparison to a Deer PSU that goodpsusearch found and a sad L&C LC-B300ATX in this thread - https://www.badcaps.net/forum/showth...24673&p=291852. I noticed it while searching the forum for details on the sad power supplies that I happened upon.

Ah, you got one of those!
What can I say about it... it's in the same class (more or less) as the iCute PSU you posted in this thread - crappy, but it can be "worked with" if you put all of the parts in side. That said, I think the iCute PSU is still a little better in terms of design, though - it uses a TPS3510 IC for monitoring the voltages, so it might have better short-circuit, over-voltage, and under-voltage protections. My L&C LC-B300ATX didn't really do a good job of detecting a short-circuit when the output wires on its floppy connector shorted, and I ended up with a smoky computer.

None of my hardware got damaged, though, due to me being there when this happened, so I was able to quickly unplug the power supply. But that experience alone was enough for me to never trust L&C PSUs that use a 2003/2005 "chip-of-the-year" PWM controller. I also have two Deer 250 Watts PSUs that are very similar to the L&C above (L&C and Deer are made by the same company - Solytech) - these, although older, are somewhat better IMO. They use a custom Deer DR-0183 PWM controller.

Originally posted by ckrtech

If you think rebuilding the L&C might be a better exercise, I can go that direction instead. The L&C claims 300 watts while the iCute claims 400.

Don't trust the labels at all.
Most low-quality PSUs aren't capable of more than 200-250 Watts continuous max, 300 Watts max peak. So you can pretty much disregard the maximum power stated on the label. Just look at the output rectifiers so that you can determine what kind of PC the PSU will be able to power (i.e. 5V or 12V -based, or both)

Originally posted by ckrtech

I do find myself wishing I had random junk parts available (such as a CRT TV board as you mentioned) so I wouldn't have to order everything from digikey. Wondering how much this iCute would ultimately run me.

....

Well, Seattle is a fairly big city, so if you do live in or near it, I'm pretty sure you will stumble on a TV on the curb sooner or later. Then there is also Craigslist free section as well

.

**ChaosLegionnaire** · 09-01-2016, 01:46 PM

Re: iCute ATX-400W/P4 Refresh with Questions

Originally posted by ckrtech

At that point in time, I believe I was using something closer to 400 watts on my personal rig - most likely my last Antec prior to moving to Corsair.

for more certainty on exactly how much your entire system is using, u may wanna consider buying a wattmeter like a kill-a-watt off amazon. how accurate it is, that is another story. however, its just to give u a rough ballpark figure of how much ac power u are pulling so u dont blow anything up since the psus u are using may lack properly working over-power, over-curent or over-temperature protection. also remember that the ac power being pulled as displayed in the wattmeter is not the same dc output that is being drawn by the system due to inefficiencies in the psu design converting the ac to dc. most junk psus have an efficiency rating of around 50-60% in the worst case scenario. so if it shows that u are drawing 250 watts of ac power, probably only 166 watts of dc power is actually being drawn since the power rating of a psu is the dc output it can deliver NOT the ac power being pulled!

Originally posted by ckrtech

If you think rebuilding the L&C might be a better exercise, I can go that direction instead. The L&C claims 300 watts while the iCute claims 400.

Originally posted by momaka

Don't trust the labels at all.
Most low-quality PSUs aren't capable of more than 200-250 Watts continuous max, 300 Watts max peak. So you can pretty much disregard the maximum power stated on the label. Just look at the output rectifiers so that you can determine what kind of PC the PSU will be able to power (i.e. 5V or 12V -based, or both)

hardwaresecrets has an article on how u can calculate a psus output power and current draw yourself by examining what kind of rectifiers they use and the voltage and current rating of the rectifiers. as an example:

Originally posted by Gabriel Torres

The maximum theoretical current each line can deliver is given by the formula I / (1 – D), where D is the duty cycle used and I is the maximum current supported by the rectifying diode. Just as an exercise, we can assume a typical duty cycle of 30%.

All these numbers are theoretical. The real amount of current/power each output can deliver is limited by other components, especially by the coils used on each output.

so as an example, lets go with the diode current ratings recommended by momaka:

Originally posted by momaka

-- install bigger schottky rectifiers on the secondary:
30 Amp 45V or higher for the 3.3V and 5V rails each, 16 Amp 60V or higher for the 12V rail (if you intend to power any PCs that require a 4-pin CPU power connector).

Big capacitors on the output of the power supply (i.e. the caps closer to the output wires) and adequately-rated rectifiers on the secondary side (typically 30 Amp schottky diodes for the 3.3V and 5V rails, and at least a 16 Amp rectifier for the 12V rail).

so for the 3.3v and 5v rail, we would have 30 / (1 - 0.3) = 42A per rail
for the 12v, it would be 16 / (1 - 0.3) = 23A

thus using Power = Voltage x Current, we would have 138.6W on the 3.3v rail, 210W on the 5v rail and 276W on the 12v rail. while these numbers look more than beefy enough for a 250w psu, remember they are only *peak* theoretical numbers, the coils and quality of caps used play a part in how much power u can draw from the psu before the ripple starts to get too high. lower power drawn = less ripple; higher power drawn = higher ripple. too high ripple will make the system unstable. it can kill the mobo caps, overheat the switching mosfets on the mobo. worst of all, too much ripple can kill your hard drive, taking away your precious data with it! so if u ever had a bad hard drive, u might wanna check your psu to see if it is probably to blame...

also, the size of the transformer, gauge of wire used in the transformer and the number of coils in the transformer also affect how much power u can draw. u can replace the output rectifiers with 100A rectifiers but if the transformer is a puny one and u try to pull something like 750W from the psu, the transformer will be the one to get fried instead of the output rectifiers!

that is why sometimes its just not worth "upgrading" a completely gutless wonder. u end up having to replace nearly every component inside and with that kind of work, u might as well have gotten another better designed psu with better internal components instead. however, for your usage scenario, powering low and medium power computers, they will do just fine and can be salvaged with some "upgrades". i'm all for re-purposing stuff to cut down on e-waste and pollution instead of just tossing it into the landfill. just dont use it on a current multi-gpu crossfire or sli setup or multi-cpu server board setup. those need a 650w or better power supply. "upgrading" a psu meant to deliver only 250w for that is just plain playing a bull in a china shop. that is why i recommend getting a wattmeter for your usage scenario, so that u know exactly what components to put into and setup each of your computers in order to not exceed the max safe power draw since the psus u are using wont be able to tell u to complain if u overload them! u dont want to overload those psus and end up frying your irreplaceable antique hardware!

hope that has taught u how to fish... how to fish for a psu's actual power rating by examining what components it has inside. believe it through observation, deduction, science and mathematics. not what is printed on the label!

**ckrtech** · 09-01-2016, 11:41 PM

Re: iCute ATX-400W/P4 Refresh with Questions

Originally posted by momaka

The things that you would really need to do is:
-- upgrade all of the output capacitors on the major rails with the following capacities:
2x 2200 uF (or higher) caps for the 3.3V rail
2x 2200 uF (or higher) caps for the 5V rail
2x 1200 uF (or higher) caps for the 12V rail or a single 2200 uF (or higher) cap
2x 1000 uF caps for the 5VSB rail
One 470-1000 uF cap for the -12V rail

I also have a -5V in this power supply which may or may not be used in an older computer at some point down the line. Are there any changes I want to make there?

The output area is certainly a place where they cram in the caps. The values and brands definitely fluctuate there as well. I believe there was a single cap that was 2200uf, and the rest were well below that. ~C29-C40

After identifying (see attachments for amusing photos rather than professional schematics) the caps associated with the various outputs, here is the translation table:

-12V
C34 220uf 16v -> 1000uf 16V
+12V
C29 680uf 16V -> 1200uf 16V
C40 330uf 16V -> 1200uf 16V
+5V
C30 470uf 10v -> 2200uf 10V
C31 1000uf 10v -> 2200uf 10V
+3.3V
C32 1000uf 10v -> 2200uf 10V
C33 2200uf 6.3v -> 2200uf 6.3V
5VSB
C21 470uf 10v -> 1000uf 10V
C22 470uf 10v -> 1000uf 10V

I imagine some of those voltage ratings will hop up a bit with the caps - 6.3V and 10V most likely turning to 16V with the rise in uf? Do you like to use the same brand/series with your entire recap, or do you recommend a specific type for the output caps and plug the rest of the holes with a different brand/series?

-- install bigger schottky rectifiers on the secondary:
30 Amp 45V or higher for the 3.3V and 5V rails each, 16 Amp 60V or higher for the 12V rail (if you intend to power any PCs that require a 4-pin CPU power connector).

I have another attachment that shows what I currently have in what I believe you called the "secondary" area (between the heatsinks) -

On the output side (above transformers in sketch) I have the STPR1020CT (?) followed by two STPS2045CT (45V 10A). I have not multimetered these guys to the appropriate places headed to the output side, however they are quite large and I assume easy to <deep breath> assume which one goes where? The guys attached to the bottom heatsink and closer to the primary are some larger transistors (C5763, C5353).

A 7805 is the closest thing I have worked to that is similar in "look" to these guys - something much simpler. When replacing these guys, do you typically desolder all legs and heatsink, remove from circuit, pull the rectifiers, clean the heatsink, install some sort of thermal pad, bolt on new rectifiers, drop it in place and solder it up? I assume I can't reuse whatever thermal whatnot is underneath those things right now and will need to order whatever it is for any replacements I drop in. Any recommendation on brand/make for replacements of schottky rectifiers?

-- install all of the missing input/primary side EMI/RFI filtering components. Typically, that consists of at least one X-rated safety cap, two Y-rated safety caps, and a common-mode choke (tip: these parts can be readily found on the boards of many CRT TVs, so if you see one busted at your local dump or on the street, just grab its board).

I'll probably have to just order these as well as map out where they go on the PCB (I assume inside the holes nearest the primary input caps) - I'll devote a bit more time to examination/study at some point in the future. Been turning this thing over and over and examining the output area and secondary area for awhile now.

Taking this one slowly and trying to put some effort/documentation into it rather than simply asking "So what should I order, momaka?" ...although I guess I still snuck that question into a few places in this post.

Attached Files

**momaka** · 09-08-2016, 07:56 PM

Re: iCute ATX-400W/P4 Refresh with Questions

Sorry for the delay in response.

Originally posted by ckrtech

I also have a -5V in this power supply which may or may not be used in an older computer at some point down the line. Are there any changes I want to make there?

Looks like capacitor C35 is used for filtering the -5V rail. So I guess just add a 10V 470-1000 uF capacitor to your list of caps for the position of C35.

Originally posted by ckrtech

After identifying (see attachments for amusing photos rather than professional schematics) the caps associated with the various outputs, here is the translation table:

-12V
C34 220uf 16v -> 1000uf 16V
+12V
C29 680uf 16V -> 1200uf 16V
C40 330uf 16V -> 1200uf 16V
+5V
C30 470uf 10v -> 2200uf 10V
C31 1000uf 10v -> 2200uf 10V
+3.3V
C32 1000uf 10v -> 2200uf 10V
C33 2200uf 6.3v -> 2200uf 6.3V
5VSB
C21 470uf 10v -> 1000uf 10V
C22 470uf 10v -> 1000uf 10V

Looks all correct to me.

For the 12V rail (C29 and C40), see if you can find 1500 uF or even 1800 uF caps. I reckon 1500 uF should be easy to find in 10 mm diameter and looks like for C40, you can only fit a 8 mm diameter cap, so you might have to use a 1000 uF cap for that.

Also, for the 3.3V and 5V rails (C30, C31, C32, and C33), you can use caps rated for either 6.3V or 10V, whichever is easier to find. Thus, you can just buy four of the same 2200 uF caps.

Same goes for the 5VSB rail. Though if you do get two 10V 1000 uF caps for the 5VSB, you can get a third one for the -5V rail as suggested earlier.

Originally posted by ckrtech

I imagine some of those voltage ratings will hop up a bit with the caps - 6.3V and 10V most likely turning to 16V with the rise in uf?

No, not really.
Capacitance (uF) and voltage (V) are separate ratings. That said, the physical size of electrolytic capacitors (diameter and height, in mm) depends on both the rated voltage and the capacitance. Therefore, it is not recommend to increase the capacitor's voltage rating unnecessarily, because then you might not be able to fit your replacement capacitor(s) in the circuit.

Usually:
higher capacitance rating -> larger capacitor size (either diameter, height, or both)
higher voltage rating -> larger capacitor size (either diameter, height, or both)

Originally posted by ckrtech

Do you like to use the same brand/series with your entire recap, or do you recommend a specific type for the output caps and plug the rest of the holes with a different brand/series?

In general, any of these capacitor brands and series will do for power supply recapping:
Manufacturer.......................... Series
Nichicon ................................ PW, PM, PS, PJ, PV, HE, HD, HW
United Chemicon (UCC) ............ KY, KYA, KYB, KZE, LXV, LXY, LXZ, KZH, KZM
Panasonic .............................. FC, FK, HFQ (old stock only), FR, FM
Samxon ................................. RS
Rubycon ................................ YXJ, YXG, ZL, ZLJ, ZLK

But from the brands and series listed above, I think Nichicon PW and HE, as well as Chemicon KY, KYB, and KZE are the most popular, both due to availability and price. A lot of folks here will also recommend Panasonic FC, FR, and FM - these are a very good choice as well. However, I will caution that some (very few) power supplies may produce a bit more ripple or become unstable with very low ESR series like FR and FM. This PSU isn't one of them, though, so you are safe to use whichever series from the above you like.

Also, for the really small capacitors that are 100 uF or less, you can use even general purpose 105C rated caps like Chemicon KMG, Nichicon VZ, Rubycon YXA, and Panasonic NHG.

Originally posted by ckrtech

I have another attachment that shows what I currently have in what I believe you called the "secondary" area (between the heatsinks) -

On the output side (above transformers in sketch) I have the STPR1020CT (?) followed by two STPS2045CT (45V 10A). I have not multimetered these guys to the appropriate places headed to the output side, however they are quite large and I assume easy to <deep breath> assume which one goes where?

Yup, you got the secondary side right.

The STPR1020CT is what is used for the 12V rail. It's a 10 Amp 200V fast recovery rectifier diode. Its current rating (10 Amps) is quite low, though, so you shouldn't use the PSU as it is right now to power any 12V-heavy PCs (i.e. one that has a 4-pin 12V CPU plug). If you plan to use the PSU for testing both 5V and 12V -based PCs, I recommend upgrading the 12V rectifier to a F16C20, FEP16CT, STTH1602CT, or similar (all of the ones listed here are 16 Amp, 200V fast recovery rectifiers). And if you only plat to use the PC with a 12V-heavy PC, then something like a STPS20S100C might be a little better due to lower forward voltage drop (since the STPS20S100C is a Schottky diode rather than a Fast Recovery diode).

As for the two STPS2045CT Schottky diodes - these are for the 3.3V and 5V rails (one for each). If you plan to power an older 5V-heavy PC such as Athlon XP or early Pentium 4 (in particular, one that does NOT have a 4-pin CPU power connector), then you might want to upgrade the 5V rectifier to a MBRP3045, SBL3045 or some other 30 Amp Schottky rectifier diode. Of course if you are upgrading the 5V rail rectifier, you might as well upgrade the 3.3V rectifier too (these rectifiers typically cost $1-2 at the most). This will help improve the overall efficiency of the PSU.

Originally posted by ckrtech

The guys attached to the bottom heatsink and closer to the primary are some larger transistors (C5763, C5353).

That's the primary side. Don't worry about changing those transistors.

Originally posted by ckrtech

A 7805 is the closest thing I have worked to that is similar in "look" to these guys - something much simpler.

7805 is a 5V regulator. I'm guessing it looked "similar" because it was in a TO-220 case (look up "TO-220 case" on google).

The SBL3045 I suggested above often comes in a case that is slightly larger than TO-220, called TO-247. TO-3P is another popular one.

Originally posted by ckrtech

When replacing these guys, do you typically desolder all legs and heatsink, remove from circuit, pull the rectifiers, clean the heatsink, install some sort of thermal pad, bolt on new rectifiers, drop it in place and solder it up?

Yes you can certainly do it that way if it makes more sense to you. Many people actually do it that way too. But that's only do-able if you have the right soldering equipment (which typically means a soldering iron powerful enough to melt the thicker joints... i.e. 40 Watts minimum with a good chisel tip).

I tend to be a bit lazy when it comes to desoldering large parts, so I usually just unscrew the rectifiers from the heatsink (which takes some patience and creative thinking sometimes) and then unsolder each rectifier diode separately. Then do the assembly pretty much in reverse of disassembly.

Originally posted by ckrtech

I assume I can't reuse whatever thermal whatnot is underneath those things right now and will need to order whatever it is for any replacements I drop in.

No, you can reuse those silicon pads as much as you like. Just make sure they are clean and free of finger oils when installing them on the new rectifiers... and also make sure the new rectifiers have their back cleaned. IPA (Isopropyl Alcohol) works great for cleaning all of that, as well as residue flux from soldering. The higher the Alcohol content, the quicker it dries too. For electronics, 90% or higher is recommended.

Originally posted by ckrtech

Any recommendation on brand/make for replacements of schottky rectifiers?

Not really. Just try to avoid eBay, AliExpress, and Amazon parts, as those could be from cheap sellers that sell factory rejects and not perform up to spec. But if you buy from a reputable online store such as Digikey or Mouser, you don't have to worry about brands.

Originally posted by ckrtech

I'll probably have to just order these as well as map out where they go on the PCB (I assume inside the holes nearest the primary input caps)

Yes, that's where the input filter parts will go. The only one to be careful with is the common-mode choke: you have to remove the metal jumpers and then insert the common-mode choke so that the continuity of its coils follows the same pattern as the jumpers. If you install the CM choke 90° off, you will blow the fuse in your PSU (and probably get a bit of sparks too... just mentioning this in case you do get it wrong so that you don't get scared)

Let me know if you have a preference from where you want to get the parts so I can help you to find those primary side filtering parts, if you want.

Originally posted by ckrtech

Been turning this thing over and over and examining the output area and secondary area for awhile now.

That's very good, because that is absolutely the best and fastest way to learn PCB layout and design, as well as how electronics actually "work".

Originally posted by ckrtech

Taking this one slowly and trying to put some effort/documentation into it rather than simply asking "So what should I order, momaka?" ...although I guess I still snuck that question into a few places in this post.

That's okay, I can help you pick your parts no problem. Just let me know what online place you prefer so I know where to look.

**ckrtech** · 09-25-2016, 09:37 PM

Re: iCute ATX-400W/P4 Refresh with Questions

momaka - I meant to thank you and once again thank you for your response. I apologize for my delay. The project is somewhat on hold at the moment, but maybe I can bang out a parts list and just pull the trigger when I have the time available.

Originally posted by momaka

Looks like capacitor C35 is used for filtering the -5V rail. So I guess just add a 10V 470-1000 uF capacitor to your list of caps for the position of C35.

Sweet.

No, not really.
Capacitance (uF) and voltage (V) are separate ratings. That said, the physical size of electrolytic capacitors (diameter and height, in mm) depends on both the rated voltage and the capacitance. Therefore, it is not recommend to increase the capacitor's voltage rating unnecessarily, because then you might not be able to fit your replacement capacitor(s) in the circuit.

Usually:
higher capacitance rating -> larger capacitor size (either diameter, height, or both)
higher voltage rating -> larger capacitor size (either diameter, height, or both)

Forgive me. I only really meant it from a supply/availability standpoint - sometimes trying to find that exact rating and size with a 10V rating is not as easy as having a selection available for 16V and just making the small jump. However - specifying dimensions for you caps definitely helps wrangle the voltage gauntlet a bit.

But from the brands and series listed above, I think Nichicon PW and HE, as well as Chemicon KY, KYB, and KZE are the most popular, both due to availability and price. A lot of folks here will also recommend Panasonic FC, FR, and FM - these are a very good choice as well. However, I will caution that some (very few) power supplies may produce a bit more ripple or become unstable with very low ESR series like FR and FM. This PSU isn't one of them, though, so you are safe to use whichever series from the above you like.

Oh that is good to know. I have mostly purchased Panasonics for my individual cap needs, but I will definitely consider the well-known brands Nichicon/Chemicon if it helps reduce the overall cost.

Yes you can certainly do it that way if it makes more sense to you. Many people actually do it that way too. But that's only do-able if you have the right soldering equipment (which typically means a soldering iron powerful enough to melt the thicker joints... i.e. 40 Watts minimum with a good chisel tip).

I have what I consider to be a pretty decent chisel tip that is my standard tip these days. My station cranks to 850F, and I generally just let it sit on 650F.

I owe you more detailed responses/questions to your responses, but my primary goal in responding was to tell you your thoughts are very much valued & time has somewhat escaped me for the moment - or at least shifted to another project for the time being.

**momaka** · 09-30-2016, 04:34 PM

Re: iCute ATX-400W/P4 Refresh with Questions

Originally posted by ckrtech

momaka - I meant to thank you and once again thank you for your response. I apologize for my delay. The project is somewhat on hold at the moment, but maybe I can bang out a parts list and just pull the trigger when I have the time available.

No problems.

I myself have been absent quite a bit lately from the forums as well. So no worries about this. If you get this project done - cool. If not, that's fine too

.

iCute ATX-400W/P4 Refresh with Questions

iCute ATX-400W/P4 Refresh with Questions

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