Are any of these psu's worthy?

[momaka]

Re: Are any of these psu's worthy?

To add to c_hegge's post...
Two transistor forward (or double transistor forward) is different from the 2-transistor 5VSB. The 2-transistor 5VSB is a self-oscillating circuit - it has no PWM chip controlling it. On the other hand, both single and doube-transistor forward topologies are always controlled by a PWM controller on the primary side - meaning that you are very likely to see 3 or more optocouplers in the power supply and only 2 transformers (one for 5VSB and one for the main power supply).

Not confused yet? There is also a signle-transistor 5VSB self-oscillating circuit, but it has a lot of similarities to 2-transistor 5VSB. Don't worry about this one, though. It's an ancient design not used since, like, forever. In fact, I think very few ATX power supplies used them. Most notably, Deer/Hyena/L&C and their variants from the late 90's and Meico (some were sold under the name "JNC" in Europe).
...
By the way, I forgot the link in my above post. Here it is:
https://www.badcaps.net/forum/showth...150#post469150

[c_hegge]

Re: Are any of these psu's worthy?

^
Current forward topology is a general term that includes any form of forward converter - be it single or two transistor. In calling it current, everell meant up to date and modern, not electrical current, since half bridge is a little dated by today's standards.

[socketa]

Re: Are any of these psu's worthy?

What is current forward topology
Buggered if i can find any info on this phrase - is there another name for it?
Is it the same as 2-Transistor Forward, or perhaps, Single-Transistor forward, topology?
Or is it a general term that includes both?

[momaka]

Re: Are any of these psu's worthy?

I just posted a breakdown of a CWT PSU and its 5VSB circuit (all the way at the end of the post).

@ socketa: have a look and comapre to yours, it's probably very similar.
Also, the output 5VSB caps on mine were just starting to fail and the 5VSB was just "starting" to act a little bit. Good caps made it behave again.

[everell]

Re: Are any of these psu's worthy?

You are trying to compare apples with oranges!

When we talk about topologies, half bridge versus current forward, we are talking about the main switching circuit. It has NOTHING to do with the 5vsb circuit.

When we talk about the "two transistor" circuit, we are referring only to the 5vsb circuit. It is normally either a two transistor circuit or has a special pwm chip used for 5vsb circuits. It has NOTHING to do with the main switching circuit topology (half bridge or current forward).

For each power supply, you must evaluate if it has a two transistor 5vsb circuit or a pwm chip type 5vsb circuit. Then you must evaluate if the main switching circuit uses half bridge or current forward topology. From there you can decide which is best for you.

Your Antec 380 uses a two transistor 5vsb circuit and current forward switching topology.

[socketa]

Re: Are any of these psu's worthy?

Thanks for the appraisal, and for making this a bit clearer.

Am going to have to find out what these 2 topologies are exactly.

(excuse me for posting the following here, when it could be posted on the other thread;
but it makes more sense to post it here - as it follows through better.)

Have got an Antec here also.
(mentioned in another thread) that has an optocoupler (i'm thinking, for the 5vsb feedback) next to the 5vsb transformer,
and on the opposite side of the case, next to the main transformer, are two side-by-side optocouplers, and no PWM transformer.

So, after reading your comments, it appears that this Antec could be a single-transistor forward topology, and therefore (if it indeed is), it is then not a "2-transitor" design.

so, can the following reasoning be used?:

psu has 2 + 1 opotocouplers on primary side, and no pwm transformer >> single-transistor forward topology >> not 2-transistor design >> PSU not a motherboard killer

have also observed, that on the antec, there is not a little capacitor around the 5vsb transformer.

https://www.badcaps.net/forum/showth...t=2-transistor
(probably should head over there, since that thread is more applicable)

[momaka]

Re: Are any of these psu's worthy?

#1, #2, and #3 are pretty much the same PSUs, made by the same company (with #1 and #2 built a lot better). 2-transistors 5VSB likely. I do have some good news for you, though - the 2-transistor 5VSB in those PSUs is actually pretty decent. Just make sure to replace the output caps on the 5VSB and all should be well. Better yet, replace all of the Fuhjyyu caps on all of the outputs. These units would make good PSUs for socket A motherboards. #3 may need some upgrades before considering it for use in a PC. I suggest you save it for later when you learn PSU topology just a tiny bit more. I think you might find it somewhat fun to upgrade. Will probably need better output rectifiers, bigger output capacitors, and possibly PI coils.

#4: Delta makes good PSUs as the other members have stated. Definitely worthy of a recap.

#5: I say stay away from this one. FSP/Sparkle put good components in their PSUs, but their designs aren't the best. Poor output voltage regulation is common (as you saw with the no-load and with the 12V light bulb as a load... even most cheap POS PSU do better than that). And many of the older FSP do have the 2-transistor 5VSB.

#6: The Hyena you have looks like a typical L&C build. Has a 2-transistor 5VSB design, but it's usually pretty reliable (many last upwards of 6 years). As for the design of the rest of the PSU - it's a half-bridge, just like the CWT/ISO PSUs. Again, it's an oldschool but dependable design with good components. This PSU will need some "upgrades" to make it decent enough to use in a PC. As with #3, I'd say save it for later to play around with. I'm using an older revision of this design to power a Pentium 3 -based PC. Works very well for that and output voltages are rock-stable.

and are these two transistors easily identifiable on the board?

Yes, fairly easy. First locate the 5VSB transformer; on half-bridge PSU designs (like the CWT/ISO and Hyena), it is *usually* the smaller transformer at the end (i.e. not the middle transformer, though not always), while on single-transistor forward PSU designs, it is always the smallest transformer.
After you locate the 5VSB transformer, look for a TO-92 transistor on the primary side. With single-transistor forward, there may be more than one. With half-bridge, there should only be one (1) if the 5VSB is of the 2-transistor type. Finally, look on the primary heatsink. One of the transistors on it should be a MOSFET close to the 5VSB transformer - this is the second transistor (hence the name "2-transistor").

And are optocouplers better idea in place of the PWM isolating transformer?

It's just a different design. Half-bridge topology uses an isolation transformer while single-transistor forward uses optocouplers.
That's because they have different parts on the primary side for the main power supply. Half-bridge has two (2) NPN BJTs, while single-transistor forward has one (1) N-channel MOSFET.

even if they have a 4-pin 12v plug for the cpu?

If a motherboard has a 4-pin 12V connector, then it draws power for the CPU from 12V rail. If there is NO such connector, then CPU power comes from 5V rail.
If you are going to use a motherboard with a 4-pin 12V connector, then a PSU with a higher current (Ampere) rating on the 12V rail is desirable. Likewise, if there is no 4-pin 12V connector, then a PSU with higher current rating on 5V rail is better.

[socketa]

Re: Are any of these psu's worthy?

Thanks wester,

Did put some oil in it, and it spins good now
Sealed the cap with RTV gasket goo

[predator0357]

Re: Are any of these psu's worthy?

I have asked you before not to double post. I am beginning to think you are just a forum predator as your title.
Its a terrible idea whats the point - you already have a used small cap in position
you may as well just leave it where it is! It is ok to do that ONLY if you have no other sources and have the equipment to test the cap before using it. If it is bad it could cause untold damage.

sorry but no1 i answering me but to others they do, so again i am sorry.
so if i will test them with ESR meter and it will show me good values so why not use them if they from good brand/series?

[selldoor]

Re: Are any of these psu's worthy?

I have asked you before not to double post. I am beginning to think you are just a forum predator as your title.
Its a terrible idea whats the point - you already have a used small cap in position
you may as well just leave it where it is! It is ok to do that ONLY if you have no other sources and have the equipment to test the cap before using it. If it is bad it could cause untold damage.

[predator0357]

Re: Are any of these psu's worthy?

Hello,
I got an idea that the small caps (like 47uf,4.7uf,0.47uf) in PSU can i get them from other PCBs like cheap PSU laying around, so what do u think about it?

[Wester547]

Re: Are any of these psu's worthy?

thanks.
yes, the fan is T&T

when it is first turned on, it spins fast, then it goes slow after 1 or 2 seconds
So could this still be due to low lubrication?

i also notice that there is a fair bit of vibration

Yes. I recommend peeling the sticker off the fan, popping the cap off if present, and seeing if the lubrication well has any oil in it (probably not). I recommend replacing at least the bulging capacitors too (but knowing CapXon all of them will eventually fail and will need to be replaced).

i put a small 12v bulb across the 12v rail
and then got a reading of 11.7v across this 12v rail

is that OK?
why does the voltage drop when a lamp is connected, and would this happen on every PSU?

So all of the voltage measurements, that i've being taking of PSUs, might be wrong, because i have being measuring the voltage across the rails with no load?

11.7V is within spec (11.4V to 12.6V is the ATX specification). It's possible every PSU you tested doesn't have stable voltages with no load.

[socketa]

Re: Are any of these psu's worthy?

thanks.
yes, the fan is T&T

when it is first turned on, it spins fast, then it goes slow after 1 or 2 seconds
So could this still be due to low lubrication?

i also notice that there is a fair bit of vibration

+12.74V is too high, I wouldn't be surprised if bad capacitors were causing that unless it has to do with the fact that the unit has little to no load on it.

i put a small 12v bulb across the 12v rail
and then got a reading of 11.7v across this 12v rail

is that OK?
why does the voltage drop when a lamp is connected, and would this happen on every PSU?

So all of the voltage measurements, that i've being taking of PSUs, might be wrong, because i have being measuring the voltage across the rails with no load?

[Wester547]

Re: Are any of these psu's worthy?

3 revolutions per second is 180 revolutions per minute - that's way too slow even for a 120mm fan to be spinning by default. Is the fan branded by T&T or ADDA by any chance? It could be running very low on lubricant and might need to be oiled. +12.74V is too high, I wouldn't be surprised if bad capacitors were causing that unless it has to do with the fact that the unit has little to no load on it.

[socketa]

Re: Are any of these psu's worthy?

Thanks

The Delta Electronics psu voltages test good - all within preferred range
But the fan spins at the rate of about 3 rotations per second
Is that too slow?
Could it be because of some tired caps, and if so, which caps?

The FSP psu fan spins fast
But the +12v rail has 12.74v which is out of preferred, and allowed, voltage variation range
Would tired caps also be causing this high voltage?

[cheapie]

Re: Are any of these psu's worthy?

From what I understand, the "critical cap" is only for the two-transistor circuits, and is used as part of the regulation circuit. With a PWM controller running the standby, the regulation stuff is done by circuitry on the chip.

[socketa]

Re: Are any of these psu's worthy?

Then, you are going to use those psus with computer that are 5V based.

even if they have a 4-pin 12v plug for the cpu?

any thoughts on this:

on the delta photo, on post #5, there is a small 47uf 50V cap
you can just see it at the bottom LH corner of the PWM isolator transformer
it's in-between the bottom of the primary heatsink and the optocouplers

since this board has a PWM control chip, instead of transistors, is this capacitor still considered to be a "critical cap"?

i.e.,
if the cap fails, does it take-out the PWM chip (or 2-transistors - in the case of no PWM control chip), then blow up the motherboard?

or am i talking a load of nonsense?

[goodpsusearch]

Re: Are any of these psu's worthy?

thanks

"1. and 2. are good power supplies from a known OEM, worth recapping but a bit outdated as far as their 12V output capabilities are concerned."
can you elaborate a wee bit on that?
i only use socket A motherboards (so, no dual-core, hyper-threading, doodackies here)

Then, you are going to use those psus with computer that are 5V based.

If that is correct, the first 2 psus would be good for that job after a recap!

[socketa]

Re: Are any of these psu's worthy?

thanks

"1. and 2. are good power supplies from a known OEM, worth recapping but a bit outdated as far as their 12V output capabilities are concerned."
can you elaborate a wee bit on that?
i only use socket A motherboards (so, no dual-core, hyper-threading, doodackies here)

on the delta photo, on post #5, there is a small 47uf 50V cap
you can just see it at the bottom LH corner of the PWM isolator transformer
it's in-between the bottom of the primary heatsink and the optocouplers

since this board has a PWM control chip, instead of transistors, is this capacitor still considered to be a "critical cap"?

i.e.,
if the cap fails, does it take-out the PWM chip (or 2-transistors - in the case of no PWM control chip), then blow up the motherboard?

[lti]

Re: Are any of these psu's worthy?

The first three are the same, but the first two use better components. I don't think any of them are actually 400W.

The best three are the Delta, FSP, and Hipro. The Delta probably has the highest output power.