did i fry my torroidal?

[mfdu]

i think i killed a torroidal.

i finally got back in and checked my 1176 projects AKA. big red and old yella.

they've been doing a great job given the limits of only doing 4:1 but it was time to open them back up. i knew it had to be a fault with C19/C20 the tanty caps. sure enough, they died when they were back to front and i didnt replace them, then thought there were other problems. replaced with equiv value electrolytics.

fixed, fired up and tested with 1kHz sine - both came up trumps.

i think i must have bumped the 0V tap onto old yellas board from the torroidal after that. came out the back of the 3pin header.

blew a fuse.

all system down.

poor old yella powers up and works fine when i plug it in to big red's torroidal. replaced the 10A IEC inlet and fuse.

do i just call the torroidal dead and replace it at this point?

chris.

 

[SSLtech]

I'm not following the description very clearly...

Are all the windings reading continuity? That's a simple test.

I don't know where the 'header' is that you mention...

 

[mfdu]

sorry mate. and thanks for getting back to me.

the "header" is just a 3pin plug to connect the torroidal tails to the pcb. my bad.

when you say "windings reading continuity", do you mean using my digital multimeter to check for +24V coming out of the torroidal?
please advise - this is the tip i am after, i suspect!!! that is how i check that there is juice actually coming out of the torroidal, isn't it?

as i said, the torroidal from the other 1176 powers the either board without a problem, so the actual psu on the pcb isn't blown.

it'll be a poo if the torroidal is dead, but at least i know the pcb is ok.

eager to hear from you.

chris.

 

[mfdu]

cool.

or not cool, i mean to say.

i have tested the primary and secondary, and there was no voltage.

thing gone poopsie.

sigh. well that adds $50 to the total ost of the project.

sob. but at least the board still works!!!!!

chris.

 

[SSLtech]

Try also checking for DC resistance with the unit not powered!!! on each and every winding. (both primaries and both secondaries assuming it has 2 of each)

Keith

 

[mfdu]

thanks for the tip keith, but i'm not sure what that will accomplish. there is simply no juice on primary or secondary when i get in on it with my DMM.
what am i looking for when checking with the unit off?

still, my GSSL build is coming along great. psu supplying the right voltages, now just gotta do the metal-work.

chris.

 

[alk509]

[quote author="mfdu"]no juice on primary or secondary[/quote]

If there's no juice in the primary, of course there won't be anything in the secondary! Check your wiring and figure out why there's nothing getting to the primary. Make sure you didn't blow a fuse.

But before you do that:

[quote author="mfdu"]what am i looking for when checking with the unit off?[/quote]

You want to measure the resistance of the primary and the secondary with your VOM/DVM, AND the resistance between primary and secondary to make sure that you don't have shorted/open windings. Plugging in a shorted primary is more trouble than it's worth, and will probably kill a fuse, or the transformer itself if a fuse isn't present. And if there's a path between primary and secondary, you'll very likely kill the actual piece of gear you're powering.

Good luck!

Peace,
Al.

 

[CJ]

Tin foil the fuze and stand back, bi-atch! :razz:

 

[mfdu]

blew two fuses.

i was kinda thinking of trying the old 303 bullet in the fuse holder. do i hear the darwin awards calling?

at this point, i am just replacing the torroidal and counting myself lucky.

as i said, at least the board fires up when using the torroidal from the other unit. therefore, board is ok.

thank you everyone for your comments.

chris.