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slr 5000 28th January 2009 10:29 PM

problem with ucd400
hi all
im after some help
my hypex ucd has developed a problem .when i first turn on the power the operating lights light up and it works no probes but after about 10 seconds or less of playing music the lights go dim untill they are completely off and the music stops

it seems to be powersupply related as the status lights on the powersupply do the same thing ( aussie amps ps3), they are bright when i first turn on the unit but after a few seconds of playing music they go dim untill they are off and the music stops

could i have some bad caps in the powersupply or could it be related to my torroid

thanks in advance for any help

DcibeL 28th January 2009 11:47 PM

Do you own a multimeter?

Did you assemble the power supply yourself? I'm not sure if the PSU that you mention comes pre-assembled or not?

slr 5000 29th January 2009 01:29 AM

hi mate
its a pre assembled aussie amplifiers ps3
the amp has been working fine for over a year but yesterday it developed the problem
it powers up fine and all the status lights come on but as soon as i play music the lights go dim and the power seems to dissapear

Eva 29th January 2009 07:35 AM

It seems that whatever you have before the power supply PCB is stopping providing power after some time.

Are you using some speaker protection or soft start boards?

A multimeter will help you to find where the circuit becomes interrupted.

The UcD modules and the power supply PCB are probably fine.

slr 5000 29th January 2009 09:49 PM

hi eva
i,m thinking it may be a problem with the toroid
its a nuvotem 1kva which another very helpfull forum member suggested may have thermal overload protection built in causing this problem
it has been over 40 + degrees c here for over 4 days in a row and my hifi room has been 45+
i suspect the heat in the room may be causing the transformer to get too hot

we have some cooler days coming which will give me a chance to test out this theory later in the week

col 30th January 2009 02:45 AM

Yes it is stinking hot here. My music room is the same. I'm powering a pair of UcD400's off of a Antrim 500VA 40-0-40 with my own power supply design and a SKAudio soft start. I'm not having the same problems.

If you are using a 1KVA trafo you must have a softstart, I'm betting on that being the culprit.


slr 5000 30th January 2009 09:43 PM

hi all
after some testing with the multi meter last night ive worked out the power supply has failed
ive got power to the inlet side but somewhere in between the inlet and outlet my power is dissapearing ,so it looks like ill buy a new powersupply and alls well again

thanks heaps to everyone for the help

col 30th January 2009 11:46 PM

you might be able to narrow it down a bit further and just replace a component. If it is just a diode or bridge rectifier at least you wouldn't have to buy the bulk storage caps. Where in Melbourne are you, if your close I could have a look. Maybe email me.


Eva 31st January 2009 02:02 PM

The power supply PCB seems way simple, the problem is probably a broken component leg, a bad solder joint or a bad connection. You may be able to easily repair it. Bending the PCB and pulling the components one by one may halp to find the problem.

Check the fuses too, sometimes they don't make good contact or the internal wire is not well attached to both ends inside.

Anthony C Smith 31st January 2009 02:27 PM

there is also the "lazy fuse" problem, where the fuse has been stressed and tempered, so it conducts but has a resistance of maybe 10 or so ohms; realy screws up power supplies!
happened on a whole batch of mosfet amplifiers we made once, killer to find, easy to fix!

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