Switchmode PSU dead

[NightProwler]

Hey all. Wonder if anyone can shed some light on this one. I have a MAAS SPS30 switchmode 30amp PSU that i use to run my Yaesu FT757 GX2. Anyway last night i turned it on and the meters lit up then it went straight back off. I checked the fuses and nothing has blown. It still doing the same thing now. Lights come on then it goes straight back off again then makes a weird buzzing/hissing noise for about 30 seconds after. Now I'm no expert but it sounds knackered to me but before I buy a new one has anyone got any ideas?

Cheers dudes...Rich

[MrWeetabix]

Things that go buzz and hiss are generally in need of some attention :-/

Is that with nothing connected too? So no chance of a short circuit etc between psu and radio?

We have a few PSU builders and repairers on here, they may be able to pass advice but to me it sounds like a case of a new PSU

[ch25]

Short on secondary winding transformer side.

[NightProwler]

Yes with nothing connected. I also noticed the fan don't seem to spin anymore but it don't stay on long enough to over heat then shut down. I'm slowly building a collection of knackered gear now. Everything seems to be breaking down lately.

[cb4ever104]

Everything seems to be breaking down lately.

I know the feeling . Think most of us on here are getting on a bit too

[NightProwler]

Everything seems to be breaking down lately.

I know the feeling . Think most of us on here are getting on a bit too

Tell me about it, Today it's my sciatica giving me hell.

Anyway I ordered a new 30amp PSU. Before I scrap the old one is it an easy fix? Where do I start?

[cb4ever104]

is it an easy fix? Where do I start?

I have 2 of those little 30A switched mode PSUs . To be honest I think I'd be scared to even open one of them up . I'm OK with the regulated ones , but I get the felling that those switched mode ones won't be easy to work on . Saying that , I might be completely wrong . You can always one it up and have a look and see if anything's burnt etc.

[1968neil]

More often than not smps (switch mode power supplies)
Will have some electrolytic capacitors that will have dried out due to heat.
A careful check around will usually find the culprit.
The feedback circuit is where I would start.
Also check diodes across the secondary windings and the associated capacitors.

73’s
Neil