UcD400HG MonoBlocks project... help please - Page 2 - diyAudio
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Old 19th January 2008, 08:02 PM   #11
glt is offline glt  United States
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I think these modules can be mounted anywhere and in Al or steel. Just make sure you apply some thermal compound (the same stuff used to mount heatsinks to PC processors) to ensure good contact. These modules are 90+ % efficient.
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Old 19th January 2008, 08:20 PM   #12
TheMG is offline TheMG  Canada
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Mounting the module to the chassis should work fine for normal use.

However if you intend to drive these at their maximum output and in a tight area with limited ventilation, heatsinking may be required.

Even though it's 90% efficient, at 400W output power you're going to be dissipating roughly 45W of heat, which may not seem like much, but if it's allowed to build up can reach some high temperatures.

I'd opt for mounting it on the side of the chassis rather than the bottom. You want hot air to rise along the side of the chassis, rather than build up a pool of hot air underneath the chassis.
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Old 19th January 2008, 08:39 PM   #13
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Scary, this advice. Start with reading the manual, page 1, where it say's "cooling" in big bold letters.

http://www.engineeringtoolbox.com/th...ity-d_429.html

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Old 20th January 2008, 12:16 AM   #14
glt is offline glt  United States
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The heatsinking will only pull the heat from the power transistors. You need some ventilation for the rest of the circuitry of the module. If you mount the modules to the bottom then the circuit board will be in a vertical position which facilitates ventilation for the rest of the circuit. I mounted mine to the side and drilled some holes under and above the module. But I don't drive the amps that hard, just normal listening volume
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Old 15th February 2008, 12:37 AM   #15
croger is offline croger  United States
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Default powersupply output voltage

so i have my monoblocks all wired up now.

TR400 transformer
ucd supply hg mono power supply
ucd400hg amp module

I do not have the power supply connected to the amp yet.
If I measure the DC voltage on the supply rails I get +/- 65.9 volts.

the ucd400hg amp is specd to max voltage input 65 volts. with over current protection kicking in at 68 volts.

I emailed hypex as well. I want DIYaudio memebers opinions as well. What issues will I have with it over the max input voltage? why is it so high off my power supply?

thanks for any input.
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Old 15th February 2008, 02:38 AM   #16
TheMG is offline TheMG  Canada
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That seems a little high. With a 40 volt tranny you should be getting a maximum no-load voltage of +/-56.5V once rectified.

It may be because your mains AC voltage is higher than 115V/230V which is what the transformer is spec'd at. This is not a bad thing, it just means you get a little more voltage out the transformer than 40V.

What doesn't seem right though is that you're getting 65V rectified, which doing the math would mean you have a 132V/264V AC mains, which seems too high to be true.

Hmmm... this definitely has me scratchin my head.

Rest assured though that it is still within the UCD400 safe operating specs (just barely) and that the voltage will sag a little once you turn up that volume knob!
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Old 15th February 2008, 03:45 AM   #17
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Default Re: powersupply output voltage

Quote:
Originally posted by croger
so i have my monoblocks all wired up now.

TR400 transformer
ucd supply hg mono power supply
ucd400hg amp module

I do not have the power supply connected to the amp yet.
If I measure the DC voltage on the supply rails I get +/- 65.9 volts.

the ucd400hg amp is specd to max voltage input 65 volts. with over current protection kicking in at 68 volts.

I emailed hypex as well. I want DIYaudio memebers opinions as well. What issues will I have with it over the max input voltage? why is it so high off my power supply?

thanks for any input.
Overcurrent doesn't trip at 65 volts, overvoltage might. All you're seeing is the unloaded voltage of the transformer, look up the regulation factor of 400VA toroid and try working the numbers again.

Since it is within the safe limits of the modules, connect them and you'll see the rails drop a few volts more even with the amps disabled, more still when they're idling, more still while under load.

It makes a big difference when you have a load on it. Don't forget to drain the caps you've charged up with a power resistor before connecting the modules.

Why waste their time by asking the same question to the forum as you emailed them with?
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Old 15th February 2008, 10:48 AM   #18
croger is offline croger  United States
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Default Re: Re: powersupply output voltage

Quote:
Originally posted by Iyremenko


Why waste their time by asking the same question to the forum as you emailed them with?

Thanks for the info. I wanted the opinion of hypex and the opinion of people on this forum is why I asked at both places. their reply is below pasted from email from Frank at hypex, who has been a great help with my project. I will post some pics of my amp when finished.

______________________________________________
+/- 66V is a little on the high side, but definitely doesn’t have a negative influence on the sonic performance. Also, when the amplifier is connected and it starts to output more power, the supply voltage will lower a bit. But as log as it doesn’t go in over voltage protection there should be no problems. When it is in over voltage protection the amp simply won’t turn on. So it is absolutely safe to connect the amplifier to the supply. But I don’t think there will be any problems with this situation.

Best regards,

Frank Veldman
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Old 15th February 2008, 10:55 AM   #19
croger is offline croger  United States
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Join Date: Jan 2008
Quote:
Originally posted by TheMG

What doesn't seem right though is that you're getting 65V rectified, which doing the math would mean you have a 132V/264V AC mains, which seems too high to be true.

Hmmm... this definitely has me scratchin my head.

Rest assured though that it is still within the UCD400 safe operating specs (just barely) and that the voltage will sag a little once you turn up that volume knob!
thanks. the building is an old buiding that was an old garment factory that is converted to a recording studio. I have all the recording studio equipment and computers, etc on ac conditioners regulated power supplies. the bench where I am assembling the UcD how ever has the power coming right off a unregulated AC main. so maybe after I hook the amps up to a regulated power receptacle the AC will be more normal.
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