Cheap PSU: Piece of junk or semi-decent?

[momaka]

Re: Cheap PSU: Piece of junk or semi-decent?

It is bad engineering practice to use resistors above their rated load.

It is bad engineering practice to use resistors above their rated load.

It is bad engineering practice to use resistors above their rated load.

And the cheap PSU manufacturers say:
It is good to save a few cents on a smaller resistor.
It is good to save a few cents on a smaller resistor.
It is good to save a few cents on a smaller resistor.

[tom66]

Re: Cheap PSU: Piece of junk or semi-decent?

Accountants and bean counters do so. I wonder if the engineers took an integrated degree on designing cheap tat.

[TELVM]

Re: Cheap PSU: Piece of junk or semi-decent?

Thanks again for all your help and good advice gentlemen .

I think I'm going to keep the original resistors, moving them from their current positions so they don't cook the neighborhood anymore, and then overkill cool them with some ghetto-mod of mine. That will tame the heat problem while not risking potential voltage issues.

I have the same PSU as well (the LC-B300ATX 300W one below).
https://www.badcaps.net/forum/showpo...&postcount=491
You may not recognize it because it has less and crappier components, but the PCB design is exactly the same.

Of course I recognize ! Mine also came with empty real state in the transient filtering corner, and also came with the infamous four diode treatment. Yours seems to have a bit less components in the output zone, and the main heatsinks look slightly different.

The good thing is, this PSU has extra holes on the PCB for another 5V rectifier (in case 30A is not enough ).

You're right!

I better play it safe, couple watts is not such a big deal

Being a newbie lacking experience I have to agree, better safe than sorry.

If you manage proper airflow for the resistors, you can disipate much more heat than what they are rated for without them burning down.

I'm gonna freeze the mthrfckrs to death .

TELVM: there is usually non-conductive stuff on them (either some color or ceramic-liek thing). But if you happen to damage it, you may get conductive places on the package and that is not good. Especially the ceramic-like stuff breaks easily.

Roger roger, will take good care to keep them electrically isolated.

[TELVM]

Re: Cheap PSU: Piece of junk or semi-decent?

OK shopping list time gentlemen .

Remember we are tailoring for a dinosaur Pentium III with 100W DC draw tops, so PSU's max power capacity is indifferent. What we pursue is crossloading management and stability (ripple, noise), insofar as this cheap old PSU allows.

1 · 470uF · 200V · SL85C · 0443(M) · Su'scon
2 · 470uF · 200V · SL85C · 0443(M) · Su'scon
3 · 2.2uF · 50V · SM105C · 0443(M) · Su'scon
4 · 2.2uF · 50V · SM105C · 0443(M) · Su'scon
5 · 22uF · 50V · TK105C · 4083(M) · YC

6 · 2.2uF · 50V · SK105C · 0443(M) · Su'scon
7 · 1000uF · 10V · SD105C · 0441(V) · Su'scon
8 · 1000uF · 10V · SD105C · 0441(V) · Su'scon
9 · 1uF · 50V · 105C(M) · VERT · RK · 0439 · DON
10 · 47uF · 50V · YK105C · 4083(M) · YC

11 · 10uF · 50V · KRM · (M)105C · 0410 · Koshin
12 · 22uF · 50V · TK105C · 4083(M) · YC
13 · 1000uF · 10V · KJH · (M)105C · 0410 · Koshin
14 · 1000uF · 10V · KJH · (M)105C · 0410 · Koshin
15 · 470uF · 16V · KJH · (M)105C · 0410 · Koshin

16 · 2200uF · 16V · TK105C · 4103(M) · YC
17 · 2200uF · 10V · LZ105C · 405B(M) · G-LUXON
18 · 2200uF · 10V · LZ105C · 405B(M) · G-LUXON
19 · 470uF · 16V · KJH · (M)105C · 0410 · Koshin



I've beeped my way investigating the relationships in the output area:

13 capacitor positive leg 'zero-beeps' with +3.3V rectifier center leg
14 capacitor positive leg 'zero-beeps' with +3.3V rectifier center leg

15 capacitor positive leg doesn't beep with any rectifier center leg

16 capacitor positive leg 'zero-beeps' with +12V rectifier center leg
17 capacitor positive leg 'zero-beeps' with +5V rectifier center leg

18 capacitor positive leg 'NON-zero-beeps' with +5V & +3.3V rectifiers center legs

19 capacitor positive leg doesn't beep with any rectifier center leg



If you suggest any variation in uF or voltage, please explain the reasons, so I can learn .

And if I'm asking too much of you just me.

[Behemot]

Re: Cheap PSU: Piece of junk or semi-decent?

For that power you can keep the input caps.

I guess 15 and 19 are for negative voltages, -12 and -5 V respectivelly. Positive is grounded, negative on blue and white wire.

[TELVM]

Re: Cheap PSU: Piece of junk or semi-decent?

I guess 15 and 19 are for negative voltages, -12 and -5 V respectivelly. Positive is grounded, negative on blue and white wire.

You are completely right sir! Cap 15 positive is grounded, negative is on mobo connector blue. Cap 19 positive is grounded, negative is on mobo white.

[goodpsusearch]

Re: Cheap PSU: Piece of junk or semi-decent?

18 capacitor --> 5V

[momaka]

Re: Cheap PSU: Piece of junk or semi-decent?

Being a newbie lacking experience I have to agree, better safe than sorry.

Meh.
Just to prove a point, I took this Deer PSU today and changed the minimum load resistors around in a very similar fashion to what I suggested to you in post #95. (More info and pictures to be posted soon this week). In short, the regulation was not good when the PSU was not loaded with anything (not even its own fan) but just the minimum load resistors. The PSU was stable, though (i.e. voltages weren't fluctuating much and the PSU wasn't hissing or whining). However, as soon as I connected a hard drive to it and added about 0.3A of load on the 3.3V rail, the voltages came to be 4.99-5.00V on 5V rail, 12.17V on 12V rail, 3.345V on 3.3V rail, -11.19V on -12V rail, -5.10V on -5V rail. That's actually not bad at all for such a light load.

Actually, I didn't do this mod only to prove a point - I also did it because I want to make a variable-voltage PSU from that one, but that's material for another thread

OK shopping list time gentlemen .

Remember we are tailoring for a dinosaur Pentium III with 100W DC draw tops, so PSU's max power capacity is indifferent. What we pursue is crossloading management and stability (ripple, noise), insofar as this cheap old PSU allows.

For most of the caps on your list, any of the series from the following brands will be suitable:
United Chemicon: LXY, LXZ, LXV, KY, KZE (KY are my personal preference)
Nichicon: PW, PS, PM, PL, PJ, PR (rare now, old stock), HE, HD (PW, PM, and HE are my personal preference)
Panasonic: FC, HFQ (rare now, old stock), FK, FR, FM (all will work for the small caps, but for the larger caps, FR and FM may be a bit too low ESR for this PSU - though I'm sure they would work just fine as I've used them myself in a similar Deer PSU).
Samxon: RS
Rubycon: ZL, ZLG, YXG, YXF
Sanyo: WX

For the smaller or less important caps (or if you really can't find any caps from the above list), you can also usually get away with general purpose 105C rated caps (though, I don't recommend it). This is what you can use:
United Chemicon: KMG
Nichicon: VY, VZ
Panasonic: EB
Rubycon: PX, YXA (old stock)

Now as far as the caps list:
#1 and 2 - you can leave the original Suscon's in there. As Behemot mentioned, they'll be good enough for many years for such a low load.

#3, 4, and 5 - keep same voltage and capacitance. Both general purpose 105C caps or low ESR caps will work, but I recommend to go with the low ESR caps especially for #5 (the 5VSB "critical" cap).

#6 and 9 - disregard / don't need change

#10, 11, and 12 - optional (keep same voltage and capacitance), but you can disregard as well

#7 and 8 - these are the 5VSB caps. Keep capacitance the same (1000 uF). Voltage can be either 6.3V or 10V (since this is the 5VSB, and the voltage is usually around 5V). You can also use more than 10V, but there's no point in doing so. Low ESR highly recommended.

# 13, 14 - these are for the 3.3V rail. Use 2200 uF caps instead of 1000 uF caps (that's what well-build PSUs usually have as a minimum). Voltage can be either 6.3V or 10V (or higher, but there's no point). Low ESR highly recommended.

# 17, 18 - these are for the 5V rail. Keep same capacitance (2200 uF) or go one step higher (2700 uF) if you want. Voltage can be either 6.3V or 10V (or higher, but there's no point). Low ESR highly recommended.

# 16 - this is for the 12V rail. This cap is tricky because you likely won't be able to find 2200 uF 16V cap in a 10 mm diameter. There's usually 4 options:
1) Reduce the capacitance to the highest you can get in 10 mm spot (not recommended). This will give slightly more ripple and noise to the HDDs.
2) Keep capacitance the same but pick a 12.5 mm capacitor (recommended, but may be very hard or almost impossible to do, depending on how much space there is around that capacitor spot).
3) Keep capacitance the same but find a general purpose 105C cap that will fit in that 10 mm spot (not recommended for the same reason as option 1 above).
Regardless which of the 3 options you chose above, make sure you capacitor is rated for 16V or more.
4) Keep the original YC TK capacitor... but then there's always the question: what if it's bad without showing it?

#15 - this is the -5V rail cap. 470 to 1000 uF caps will work fine. Voltage rating can be 10 or 16V (or more, but not needed). Low ESR recommended. Make sure to put the new cap properly (negative side on the -5V rail and positive side on ground).

#19 - this is the -12V rail cap. 470 to 1000 uF caps will work fine. Voltage rating can be 16V or higher. Low ESR recommended. Make sure to put the new cap properly (negative side on the -12V rail and positive side on ground).

I think that covers them all.

[Behemot]

Re: Cheap PSU: Piece of junk or semi-decent?

You can get Samxon GT too.

As for D10 caps, Joe still has Samxon RS in 3300 uF D10, just the price is nothing extra since I discovered eBay and DigiKey with Chemi-Cons and other caps. Also he has these periods when he is nto available for month or two (seems like it's right now). On the other, only another reliable source of low-esr (not ultra-low) 3300 uF in D10 I know of is here, BadCaps shop. These are custom ones, e. g. Samxon RS is not normally manufactured in 10mm diameter by Man Yue.

You may not need 3300 uF here, but if you will be repairing any better 400W+ PSU in future, you most likely won't be able to do it without these.

[TELVM]

Re: Cheap PSU: Piece of junk or semi-decent?

Again thanks a lot for all your great help gentlemen . Here, a token of gratitude :

Tentative shopping list:

1 · 470uF · 200V · 85C · Su'scon--------> (Stays)
2 · 470uF · 200V · 85C · Su'scon -------> (Stays)
3 · 2.2uF · 50V · 105C · Su'scon --------> Panasonic FC · EEUFC1H2R2 · 2.2uF · 50V · 105C
4 · 2.2uF · 50V · 105C · Su'scon --------> Panasonic FC · EEUFC1H2R2 · 2.2uF · 50V · 105C
5 · 22uF · 50V · 105C · YC --------------> Panasonic FC · EEUFC1H220 · 22uF · 50V · 105C

6 · 2.2uF · 50V · 105C · Su'scon --------> Panasonic FC · EEUFC1H2R2 · 2.2uF · 50V · 105C
7 · 1000uF · 10V · 105C · Su'scon ------> Rubycon ZL · 10ZL1000MEFC8X20 · 1000uF · 10V · 105C
8 · 1000uF · 10V · 105C · Su'scon ------> Rubycon ZL · 10ZL1000MEFC8X20 · 1000uF · 10V · 105C
9 · 1uF · 50V · 105C · DON -------------> (Stays)
10 · 47uF · 50V · 105C · YC -------------> Panasonic FC · EEUFC1H470 · 47uF · 50V · 105C

11 · 10uF · 50V · 105C · Koshin ---------> (Stays)
12 · 22uF · 50V · 105C · YC -------------> Panasonic FC · EEUFC1H220 · 22uF · 50V · 105C
13 · 1000uF · 10V · 105C · Koshin ------> Panasonic FC · EEUFC1A222L · 2200uF · 10V · 105C
14 · 1000uF · 10V · 105C · Koshin ------> Panasonic FC · EEUFC1A222L · 2200uF · 10V · 105C
15 · 470uF · 16V · 105C · Koshin -------> Rubycon ZL · 16ZL470MEFC8X16 · 470uF · 16V · 105C

16 · 2200uF · 16V · 105C · YC ----------> Rubycon ZL · 16ZL2200MEFC12.5X25 · 2200uF · 16V · 105C · (12.5mm Ø)
17 · 2200uF · 10V · 105C · G-LUXON ---> Panasonic FC · EEUFC1A222L · 2200uF · 10V · 105C
18 · 2200uF · 10V · 105C · G-LUXON ---> Panasonic FC · EEUFC1A222L · 2200uF · 10V · 105C
19 · 470uF · 16V · 105C · Koshin -------> Rubycon ZL · 16ZL470MEFC8X16 · 470uF · 16V · 105C



You sure we don't need to replace the two big ones? They're already free, I went solder-happy and all the cattle is out of the corral .

[goodpsusearch]

Re: Cheap PSU: Piece of junk or semi-decent?

If you had an esr/capacity meter you could measure them to make sure they are 470uF caps. L&C loves to use fake capacity primary caps.

[momaka]

Re: Cheap PSU: Piece of junk or semi-decent?

The list looks great, especially with those Panasonic FC for #13, 14, 17, 18. Stability guaranteed .

You sure we don't need to replace the two big ones? They're already free, I went solder-happy and all the cattle is out of the corral

Well, I wouldn't really call them free. They'd probably be at least $3 to $4 each . And also, they almost never give any problems unless they are of a very crappy brand such as CapXon. In my experience, Suscon's capacitors have been okay. I'd say probably just a level below Teapo and Ost, perhaps on par with Ltec and Elite. So I expect their high voltage caps to be okay too.

If you had an esr/capacity meter you could measure them to make sure they are 470uF caps. L&C loves to use fake capacity primary caps.

Yes, the YC caps they use almost always seem to lie about their rating (usually just a notch higher, as in showing 330 uF when they are labeled 470 uF, or showing 220 uF when labeled 330 uF).

Judging by the size of those Suscon's caps, they may not be lying about their rating. And even if they were, 330 uF is more than enough for a Pentium II/3 PC.

[TELVM]

Re: Cheap PSU: Piece of junk or semi-decent?

Got a couple multimeters but none of them can read capacitance .

While we're at it and just to be sure, how about a couple of these for the primary:

Panasonic EE TS · EETEE2D471HJ · 470uF · 200V · 105C


Another option: If 'Cheng' isn't a hopeless brand, I could swap big caps between the Allied and the 'TOOQ' PSUs.

[goodpsusearch]

Re: Cheap PSU: Piece of junk or semi-decent?

If you are going to buy new primary caps, I suggest you to choose 560uF or 680uF capacitors. This will help the psu do a couple of more watts and this could help its longevity.

[TELVM]

Re: Cheap PSU: Piece of junk or semi-decent?

These are even cheaper than the 470uF:

Panasonic TSHA ECOS2DA681CA · 680uF · 200V · 105C

[momaka]

Re: Cheap PSU: Piece of junk or semi-decent?

Another option: If 'Cheng' isn't a hopeless brand, I could swap big caps between the Allied and the 'TOOQ' PSUs.

They (likely) are hopeless. The Suscon's are a lot better IMO.

Or if buying new, both the Panasonic TSHA 680 uF and the TS 470 uF will work fine.

[Behemot]

Re: Cheap PSU: Piece of junk or semi-decent?

Come on man, srsly, WTF? Words like good and better are not to be messed in one sentence with Suscon, Jee, HEC, GSC, Cheng and other generic brands. Its all chineese crap. Period

[tom66]

Re: Cheap PSU: Piece of junk or semi-decent?

Suscon are rubbish, as bad as Teapo are. On here, they die a lot in monitors.

[momaka]

Re: Cheap PSU: Piece of junk or semi-decent?

Suscon are rubbish, as bad as Teapo are.

For output filtering caps, I understand.
For high-voltage bulk storage, I haven't had problem with either and they are both fine for that IMO.

[tom66]

Re: Cheap PSU: Piece of junk or semi-decent?

Yeah, they should be fine in that application.