This Chieftec ATX-410-212 screams

[pdavid]

This problematic Sirtec built unit gives an extremely loud high pitched noise. Maybe it's a design error... or intention. Many of these units weren't even lived up till they waranty expired.
In the 5vsb circuit there is a 4.7uF capacitor bent right in top of a diode. In time the capacitor simply fries and the 5vsb voltage goes way up high. As it goes above 6.2 volts a zener diode gets shorted. After this the protection won't let the unit power up and the psu gives an audable squeal. That's all the info I aquired and since I got one of this faulty psu I decided to apply this simple fix, just to see if it works out. Someone definately tinkered with this thing before, but it probably didn't work. Anyway I replaced the problematic cap and zener, secondary caps. Checked primary transistors and fet and secondary schottky diodes too. All measured good.
I noticed that this psu has several burn marks, one under the 5vsb protection zener and another next to the big transformer where on the R603 A B C D resistors are in paralell on the other side...
So I "fixed" it and now it's louder then ever. Literally painful to listen to and after a minute the sound even get's worse with a buzzing, rattling noise. When I disconnect the AC power, the squel goes away with a click.

I removed the heatsinks again to see if there is a short, but everything measures good, smd components too. My guess is to replace all the small capacitors and then see what happens. If that doesn't work then maybe I need to replace the 5vsb transformer or the opto or this amazing SG6105D... Too bad I don't have a scope now.

Any thoughts?

[selldoor]

Re: This Chieftec ATX-410-212 screams

Hi - welcome to the forum - thankyou for the good pictures.
Can you pinpoint where the squeal comes from (using a cardboard listening tube) or fat straw. A couple of things on the pictures - last pic there is a green cap appears to have a brown stain on top - does it? and what make is it. Pic 3 again I think its the same green cap looks brown on top.. and also going from where it says HS3 on the board towards the copper coil - between a small cap and a bigger one ther is a brownish component with a cream swirl with what looks like a hole in it. What is this and does it look ok to you?

[selldoor]

Re: This Chieftec ATX-410-212 screams

I see it now the cream swirl is just white glue. I have been looking at more pictures of this board and most of the caps were TEAPO or GLUXON. If yours have these they probably all need changing.



Have you seen the articles on this site - if you dont read Polish you can use google translate
to translate to English or Hungarian

[ben7]

Re: This Chieftec ATX-410-212 screams

Try replacing the 820uF 200v teapos, since you said the transformer makes a rattling/buzzing noise. Also it will whine when there is not enough capacitance (i.e. a capacitor is bad).

-Ben

[selldoor]

Re: This Chieftec ATX-410-212 screams

Ha Ha missed putting the link in
http://www.elektroda.pl/rtvforum/topic1355352.html

[pdavid]

Re: This Chieftec ATX-410-212 screams

I see it now the cream swirl is just white glue. I have been looking at more pictures of this board and most of the caps were TEAPO or GLUXON. If yours have these they probably all need changing.



Have you seen the articles on this site - if you dont read Polish you can use google translate
to translate to English or Hungarian

I've already changed all the secondary caps to brand new Yageo SC/SY, Samxon GT.
I took out the primary caps and they measured 750-770uF. A bit low but I don't think they cause the problem. The sound comes from the 5Vsb's transformer. I've read the polish site before, it was very helpful. Maybe the transformer got damaged somehow. I'm going to strip down the unit to bare pcb (on the primary) and look for failed components. For example the two resistors on pic 2 show some signs of damage, but they measure ok. Also last time I managed to short the primary heatsink to a resistor so maybe things are even worse I won't be home until tuesday so it's only theory now.

[selldoor]

Re: This Chieftec ATX-410-212 screams

There is by coincidence another thread running on badcaps with another screaming
chieftec - perhaps you can compare notes.

[pdavid]

Re: This Chieftec ATX-410-212 screams

This is no coincidence I've chose to fix up this chieftec psu to see if there are any similarities between the two. But Enhance and Sirtec are too diferent in this case. The only similar factor is "the natural bad intention and stubborness of electronic devices"...

[ben7]

Re: This Chieftec ATX-410-212 screams

Hmm, the only other electrolytic cap in that circuit would be the startup cap, but I don't see how that would make it whine. Test the cap circled in red in the attached photo, I believe that is the startup cap.

-Ben

[tom66]

Re: This Chieftec ATX-410-212 screams

The squealing can be caused by the glue in the 5vsb trafo drying up, it is not easily fixed.

[pdavid]

Re: This Chieftec ATX-410-212 screams

Hmm, the only other electrolytic cap in that circuit would be the startup cap, but I don't see how that would make it whine. Test the cap circled in red in the attached photo, I believe that is the startup cap.

-Ben

Yeah that is the startup cap and it was burned to a crisp. First thing was to put a brand new 4.7 50v Nichicon there. Still the whistleing remained. So I'm going to take the whole thing apart and replace all the other small caps as well.

[momaka]

Re: This Chieftec ATX-410-212 screams

For example the two resistors on pic 2 show some signs of damage, but they measure ok.

If I'm not mistaken, those resistors, along with the 2 electrolytic caps and diodes next to them are for boosting the voltage on the primary side when the PSU is in standby to supposedly increase the efficiency in standby mode. But that circuit is a complete waste of components and energy as it doesn't do anything. See this post and follow the links in it...
https://www.badcaps.net/forum/showpo...31&postcount=3
If you have the same circuit on your PSU, it's safe to remove it (you should IMO, as it does absolutely no good).

As for the standby circuit - check all of the ceramic caps for short circuit. Ceramic caps like to short out when they fail. A bad standby transformer is another possibility, like you mentioned. You can do a simple check on the standby transformer: on the primary side of it, there should be 4 or 5 pins. They are usually grouped in 2 sets, one with 2 pins the other with 2 or 3 (depending if you have 4 or 5 pins). Each set should have continuity between it's points, but there shouldn't be continuity between the two sets.
Lastly, perhaps it could also be a bad optocoupler (or did you check that already?).

[pdavid]

Re: This Chieftec ATX-410-212 screams

As for the standby circuit - check all of the ceramic caps for short circuit. Ceramic caps like to short out when they fail. A bad standby transformer is another possibility, like you mentioned. You can do a simple check on the standby transformer: on the primary side of it, there should be 4 or 5 pins. They are usually grouped in 2 sets, one with 2 pins the other with 2 or 3 (depending if you have 4 or 5 pins). Each set should have continuity between it's points, but there shouldn't be continuity between the two sets.
Lastly, perhaps it could also be a bad optocoupler (or did you check that already?).

Thanks for the tips. I took apart the primary side. I was clumsy and before discharging the primary caps I shorted the heatsink with a resistor... it gave a blue spark. Anyway, it turns out the two small teapo caps (2.2uF 50V) and the ones in the booster circuit (2.2uF 400V) are giving bogus capacitace readings like 3.6uf, 4.8uf, sleeves are slightly discolored. I'll test the esr of the big ones later.
Primary switchers and standby fet test ok. Trafos and opto are ok. There is an smd npn transistor in the standby circuit and a ceramic cap, those are good but the 6.2V zener is shorted again. Movs, foil and y caps aren't shorted but I'm going to replace them anyway.
That's all so far. I'll probalby get back to this thing on friday.

[pdavid]

Re: This Chieftec ATX-410-212 screams

I changed every single capacitor, tested all transistors and diodes even swapped an sg6105d from a known good psu. It still whines. I get 5vsb and pwrgood signal only and when I try to start the psu (with load) it only powers up for a second then clicks and rattles while voltages are below 1.3V excpet the 5v standby and power good. There has to be a short somewhere... maybe. I'm going to get a scope.

[RJARRRPCGP]

Re: This Chieftec ATX-410-212 screams

This problematic Sirtec built unit gives an extremely loud high pitched noise.

That part on the PCB (resistor?) looks like the ones on my Deer DR-250ATX!

The PCB on my Deer PSU looked like that, but in more places!

Are you talking about squealing? Squealing reminds me of my PowMax LP-6100(C?) 300W PSU purchased in 2002.
And that's one of the better ones and it looked fine when it was opened up.
I noticed it constantly squealing in 2003 (like a CRT TV) and thus replaced it in July, 2003.

[RJARRRPCGP]

Re: This Chieftec ATX-410-212 screams

the sound even get's worse with a buzzing, rattling noise.

I would be even more worried about a rattly buzzing sound.
Makes me suspect a primary issue.
And with my 2005 SmartPower 2.0 500W PSU, I sometimes heard buzzing and it sounded like AC line frequency buzzing vibrating the PC case! O_O!
(But it was before the latest fiasco with the PSU)

[ben7]

Re: This Chieftec ATX-410-212 screams

I changed every single capacitor, tested all transistors and diodes even swapped an sg6105d from a known good psu. It still whines. I get 5vsb and pwrgood signal only and when I try to start the psu (with load) it only powers up for a second then clicks and rattles while voltages are below 1.3V excpet the 5v standby and power good. There has to be a short somewhere... maybe. I'm going to get a scope.

Hmm, well then, it could be some sort of feedback problem.
Better check the opto's and the resistors in the feedback circuit(s).

-Ben

[pdavid]

Re: This Chieftec ATX-410-212 screams

Hmm, well then, it could be some sort of feedback problem.
Better check the opto's and the resistors in the feedback circuit(s).

-Ben

So I changed the opto. Resistors are good on the feedback path. It still won't operate. Using a paper tube it sounds like that the feedback's trafo is making the squealing. I can't find a trafo with the same pinout, maybe I'll swap pins on one and give it a try. I have like 40 minutes a day after work for this psu. I fixed two forton 400pnf once in less then 40 minutes and they work ever since. Troubleshooting this thing is hard.

[pdavid]

Re: This Chieftec ATX-410-212 screams

There was a short after all, under the 12V rail's capacitor
The psu only whines when in standby otherwise it's silent, with little load of course.

[c_hegge]

Re: This Chieftec ATX-410-212 screams

11.8V on 12V1 and 12.0 on 12V2, when this is only a single rail PSU?