FSP400-60GLN worth fixing?

[Behemot]

Re: FSP400-60GLN worth fixing?

I think it should be +5 V.

[Elitist]

Re: FSP400-60GLN worth fixing?

Yup. Everill gives 5.10V

[Elitist]

Re: FSP400-60GLN worth fixing?

Doesn't get any better! 'Repaired' two now. Second one runs fine off-load, SB is up, but connect to a board and it stops after a few seconds, SB goes down. These things must be fixable, but the title of the thread could be rhetorical. In my case, time is not a problem so will persevere and do a full recap, particularly as the major components and design seem to get heads up.

[Elitist]

Re: FSP400-60GLN worth fixing?

More testing with R-loadings confirms only +3.3 & +12V lines susceptible, 5V OK at all loadings. As previously observed, perhaps just some caps on some positions go bad?

Just gets worse: it ain't the diodes, it ain't the caps - all new! So what can permit an orderly start up but not sustain the rated current? Doesn't sound like an FET/semi - they're usually all-or-nothing/big bang/black burn marks! Anyway - the +5V line is good.
Puzzled...

[Per Hansson]

Re: FSP400-60GLN worth fixing?

Without starting the main rails can you load the 5VSB down to whatever the label says it's rated for without problem?

[Elitist]

Re: FSP400-60GLN worth fixing?

Yes - that's what's so perplexing. Tack, Per.

[Per Hansson]

Re: FSP400-60GLN worth fixing?

Doesn't get any better! 'Repaired' two now. Second one runs fine off-load, SB is up, but connect to a board and it stops after a few seconds, SB goes down.

Ok, it was the above quote that had me confused.
Because here it sounds like you just connect a board and don't start it.
And after a while 5VSB dies.

[Elitist]

Re: FSP400-60GLN worth fixing?

Correct!

[Per Hansson]

Re: FSP400-60GLN worth fixing?

Scratch that: I'm still as confused!

[Behemot]

Re: FSP400-60GLN worth fixing?

IIRC the driving circuitry and also the FET gates are powered by an auxiliary output from the SB transformer. If either of them are bad, the SB can drop or even go to protection mode. I think it has been previously mentioned here? Or maybe in other thread; somebody had the primary PWM driver bad or something like that.

[Elitist]

Re: FSP400-60GLN worth fixing?

Confused - at least two of us!
Oh dear, all gets more convoluted once the drivers & semis get involved! "..go to protection mode." sounds very much like a rational diagnosis here, especially as the whole thing restarts after removal of the load, switch off and restart ~couple of minutes later when all lines come back up. Can you suggest any particular component(s) to inspect in the PWM/driver circuitry? May be worth chasing this explanation down for this unit as I saw very similar effect on one of the earlier failures. (May still be kicking around not yet stripped for parts!).
Apart from that, this thread is/has been a wonderful learning experience for YT, maybe others, too.

[Per Hansson]

Re: FSP400-60GLN worth fixing?

Well Elitist your posts have me confused, let me give you some background.
I have a PSU (linked below) where the 5VSB goes into protection mode with a medium to strong load.
I.e. it is fine with a low load of a few watts but if I connect a mainboard it will boot then power off suddenly:
The reason is that the 5VSB gets overloaded, it has nothing to do with the main PSU (+3.3v, +5v, +12v, -12v)

Now in this particular case I think it's the 5VSB transformer that is bad.
But I have no way to test my theory because I have not been able to find a replacement.

That's why I asked you the questions I did above in post #125 & #127
In my opinion what you wrote in your post #128 is contradicting:
There should be no difference in having a dummy load on 5VSB vs having a mainboard as load, because there is no external monitoring.
-Only load monitoring of the 5VSB line itself, that is unless the mainboard presents a load of more than what 5VSB is rated for (commonly 2A).

https://www.badcaps.net/forum/showthread.php?t=49596

[Behemot]

Re: FSP400-60GLN worth fixing?

I'll try to think about you when I'll be ditching some. Well actually I may even have some board with a SB transformer still in…gonna have a look.

[Elitist]

Re: FSP400-60GLN worth fixing?

I think you may have hit on a shortcoming of my usual testing routine? Ever since starting to test (working or not) PSUs many years ago, I have been in the habit of loading the +5V line before switch-on with a 10ohm ww (0.5A) [used to be necessary for some AT supplies which only switched on with a loading . I will now recheck. Yes, SB is rated 2A and didn't go down with a 5ohm load. Rechecked with a 2.2ohm load - SB stays UP. No change with SB on 2.2ohm load and 10ohm load on +5V rail.
Uh ...where next? and thanks for your continuing interest/offer - perhaps another SB transformer isn't called for?

[Behemot]

Re: FSP400-60GLN worth fixing?

Found one board which already lacks the transformer since my last experiments I guess…maybe next time

[Elitist]

Re: FSP400-60GLN worth fixing?

Ha! Not to worry, but appreciate it you could tell which one it is for future reference, děkuji.
More testing: As before +5V and +5VSB seem totally robust but 3.3 & 12V lines support 36ohm loads but not 15ohm ditto. Is my logic (sorry about pun) correct that the SB is OK and that the issue lies within the 3/5V rails? If I can pin this down, I'll be able to resurect three units...

[Behemot]

Re: FSP400-60GLN worth fixing?

My patience with these craps is already running out. Took one 350watter which looked fine, only full of dust and OFC caps bloated, but no heat damage anywhere. Did complete recap with my new Rubycons, guess what. Frelling 3 V @+5 V SB and 2.4 V @PWR On.

If I knew it will be another piece of stubborn crap, I'd take something else to refubish. Especially now when I have like one more day to collect some HW elsewhere and than put like 6 PCs together from that

Good that this is one of the last units, got one Epsilon and than normal units which only need recap and they WORK

[Elitist]

Re: FSP400-60GLN worth fixing?

Indeed! I have a bunch of cheap, simple PSUs - change a couple of caps and they're good for another 3/4yrs. HEC and SCL are favourites, but expensive, complex ones like OCZ contain the same old cheap, faulty caps/components as well as other design shortcomings.
As far as these FSPs are concerned, though, they represent a certain challenge. Clearly, the design is OK, as acknowledged earlier, they run for 2-3yrs - it's the components that are dud. So, change the caps - still not working 100%; what else is failing? Semis? Transformers? Or, maybe, a minor control component? Like a detective novel. Looking on the brighter side, perhaps there's lessons to learn apart from binning the unit and creating even more landfill?
For the record, changed the R92 & D90 which were badly burned - seemed to have approx correct values in circuit but when removed there was a layer of char underneath from the carbonisation of the spot of adhesive used to secure before reflow soldering.
Any further ideas on my failing 3 & 12V lines very welcome...

[Elitist]

Re: FSP400-60GLN worth fixing?

FWIT (I know you guys like your mnemonics - perhaps I should label myself TW*T, choose your own vowel), I have read through all seven pages of thread again. Understood about 50% (not an electronic/electric engineeral, or even an engineer of any sort). Seem to have followed all your best bits of advice, got the 5VSB running, restored all the OPs, got full power on 5V. What puzzles me is, if, all caps & Ds replaced, the amps and volts get that far down the trail how can it just be the 3&12V rails, which are working, fail to provide big amps? Surely must be down to a single faulty but not broken component or group thereof? Bet Snr. Everell from Va. knows the answer judging by the pain and suffering he's experienced working on these...

[Elitist]

Re: FSP400-60GLN worth fixing?

DM311/Fc270 & 6800 - where are these located, please? Circuit numbers? Can Q12/13/30/31 be adequately tested in circuit (static), power off?