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Class D Switching Power Amplifiers and Power D/A conversion

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Old 22nd March 2006, 01:33 AM   #1
snkby is offline snkby  United States
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Join Date: Jun 2005
Location: northern california
Default ucd180 powers on then off. please help.

i just put together a pair of the ucd180 modules running with +/-42.5v.

i know its almost to the max +/-45v but its still well below the self-protect of +/-52v.

at first i just wired 1 amp to power-on so that if anything went wrong i would lose just that 1.

like a knucklehead i had the volume on the portable cdp at max instead of min.

of course when i powered-on the amp i about crapped my pants and quickly turned down the volume.

i slowly increased the volume but no output.

i figured it went into protection mode and would be ok after a minute or so.

i then wired the second amp to power-on while i waited.

after about 10 minutes i powered them both on and the blue leds on them lit so i figured good to go.

as i reached to turn up the volume the leds went off.

so i disconnected power from the amps and the leds came on again while the caps discharged.

what happened ?

whats happening ?

thanks.
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Old 22nd March 2006, 03:37 AM   #2
snkby is offline snkby  United States
diyAudio Member
 
Join Date: Jun 2005
Location: northern california
Default problem solved. the psu i made was

stable @+/-42.5v for hours before i used it to power the ucd180 modules so i figured it was good.

after the wierd powering-off i measured the rails and found i had a very leaky cap.

1 rail was measuring 57v and the other was 28v.

i replaced the caps with some larger ones i had laying around and everything is great now.

output is still +/-42.5v and then drops to +/-39.5v under load.

letting the amps play for a while before i put them in the main system.
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