liteon D30573H - no power

[socketa]

Hello,
Only get 2.8V on 5VSB, no green LED, no fan spinning (or twitch).
Being in storage for about a year.
The vent of larger green cap, to the left to the smaller coil, is slightly bulged.
Could that be causing it not to start?
Does this PSU have "start up" cap (whatever that is), and could that be it?

[goodpsusearch]

Re: liteon D30573H - no power

5vsb output caps need to be checked/replaced.

5vsb is generated with IC on this psu. Check for shorted/leaky diodes around the 5vsb circuit.

[CapLeaker]

Re: liteon D30573H - no power

Actually it did start, other than that you wouldn't have any 2.8v. Something is holding it back. Maybe check the feedback circuit? Last week I had a different PSU doing exact the same thing only to find out it had a bad cap right in the beginning of the feedback circuit on the secondary.

[socketa]

Re: liteon D30573H - no power

That cap was a 10v 1000uf teapo SC, and it was bulging from underneath - also
it meaused 400uf and 2.5 ESR
Traced the positive terminal through a coil to the 5VSB rail.
Replaced it with Suscon SD (does that sound good enough?) and works fine now.
Was the 5VSB voltage feedback going to the input of a control chip, and because the output voltage was too low the chip refused to return a power good signal and liven up the other rails?

[CapLeaker]

Re: liteon D30573H - no power

Nice fix! I don't have a schematic or trace... so I dunno what that cap is doing. It was just that recently I had this problem here:
https://www.badcaps.net/forum/showthread.php?t=51953

[stj]

Re: liteon D30573H - no power

Replaced it with Suscon SD (does that sound good enough?)

NO.
use a Panasonic FR or some other decent cap.

[socketa]

Re: liteon D30573H - no power

No FR caps on hand. And not viable to order.
It's just going to be a backup PSU - possibly sitting in a box for years to come.
How about Ltec LZG? It's ripple and ESR specs are in the same ball park as the faulty teapo cap.

[CapLeaker]

Re: liteon D30573H - no power

Just put a better cap in it next time it is viable. Sometimes you just have to make do with whatever you have on hand. Happens to me quite often. It may not be perfect, but it will work for now.

[Wester547]

Re: liteon D30573H - no power

No FR caps on hand. And not viable to order.
It's just going to be a backup PSU - possibly sitting in a box for years to come.
How about Ltec LZG? It's ripple and ESR specs are in the same ball park as the faulty teapo cap.

Probably not a good idea either. A couple of relatively recent threads here show a bunch of LZG blowing up under relatively low thermal drudgery. Su'scon are known to quickly die under high heat conditions as well (IE LCD monitors). And the output of a flyback converter (+5VSB) means high ripple current.

However, neither Su'scon nor LTEC would be considered worse than Teapo (maybe a slight hair better). If this isn't a mission critical repair, I suppose it isn't a big deal. And the rest of the Teapo (and tiny LTEC?) capacitors probably aren't in great condition either, so if you didn't replace those maybe next time you get the unit out you could do so if you like, and maybe change the Su'scon for a nice Panasonic like stj said. Oh, and that's a Hipro, not a Lite-on.

[socketa]

Re: liteon D30573H - no power

Thanks
The ESR meter shows the LTEC to have 0.030 ohms ESR
So removed the Suscon, and popped in the LTEC, and all runs fine.
Was nice to actually have fixed something - rather than the usual dead end.

[Behemot]

Re: liteon D30573H - no power

Can send ya some NCC KZH or KZN dirty cheap…

[socketa]

Re: liteon D30573H - no power

Thanks bud, but it's cool.
I'm happy with that LTEC cap, since it's ESR and capacitance test good.
Now i know what might be the problem if it fails to start again.