UcD400 Q & A

[matjans]

well before the output filter there is a pwm carrier signal at (i believe) ~450khz. Despite hypex being very careful in creating a pcb that radiates as little emi as possible, some tuners are pretty sensitive to this stuff.

jp, wouldn't it be nifty if you could change the low-voltage output on the psu board with a trimpot in stead of making it 15V fixed? Looks like it'c nicely regulated..

[Bgt]

Matjans, I see some ripple on the speaker wires, some 420khz, but this is so little. Dont know if it goes out through the mains wire but it should not. Have to see with a scoop and pickup inductor what happens.

[R Dijk]

Originally posted by ackcheng
Seems like a mixture of old and new modules. Any problem?

Its the old normal ucd 400 rev 1 driver board, and ad8260 rev 2. No ploblem at all. Only one comment to the supplyed signal wires, the soldering for the mute wire i had to redo as 3 where no good.

Psu is as posted in post #742

[matjans]

use coaxial speaker cables!

edit: zelfs op zondag werken jp?

[Jan-Peter]

An EMI measurement on the latest version of the UcD400. FYI 30dBuV/M is the official limit.

Jan-Peter

Tja, altijd hé

[ghemink]

Originally posted by ghemink



I'm indeed using the DEQX crossover. I plan to use 2 UcD400 in bridge for the woofers (2 x Vistaton TIW200XLS in a dipole, or more like an U-type frame) or one UcD400 per woofer (so not bridged). For the midwoofers I use two Seas Excell W18EX001 per channel (also dipole) and the tweeters are the Vifa ringradiators. The mids and tweeters are now running with UcD180s, sounding very well. However, since the UcD400 seems to be better spec'd than the UcD180, I want to try the UcD400s also for mid and high. Using a bridged configuration for the woofers will also avoid power supply pumping effects when I uses an SMPS. Power supply pumping with an SMPS could be a problem since the SMPS uses relatively small caps in the LC filter (2x470uF per rail).

Almost finished building one SMPS, just need to get some thermal conductive paste for the power mosfets and rectifier diodes (the paste was not in the kit). I don't really want to fire it up without the transistors being thermally connected to the heatsink.

Best regards

Gertjan

I have the SMPS working. Just test drived it on a 90W lightbulb for half an hour or so, in fact it was a 60W lightbulb for 100V, but I had about 125V out (+ and - 62.5V). So the bulb was a bit overloaded and I guestimate that I delivered about 90W.

Under that load condition. I have a 100Hz signal of about 0.35V RMS sitting on the 62.5V and about 30mV RMS 75kHz switching frequency and a few harmonics.

I have nothing modified yet. I will later this week try it with more load. Had it not yet heatsinked, just the power MOSFETs and the diodes mounted on an Aluminum L profile that is meant to bolt it to a heatsink. Even after half an hour or so at 90W, this L profile did not get very warm (did not measure temperature but felt not hot, just nicely warm, 40C??).

I want to improve the regulation behavior to suppress the 100Hz more. I also want to make the slowstart slower (increasing one cap in value) since currently, when starting up with the lightbulb load in place, I get an overshoot to +- 72V before the output voltage settles at +- 62.5V. Probably the overshoot disappears when I make the slowstart slower.

Best regards

Gertjan

[ackcheng]

May I ask what's an SMPS

[matjans]

Switch Mode Power Supply

[ackcheng]

I see! But other than having a smaller physical size? what benefit does it have over the linear power supply? We have been trying to modify digital equiptment and the first thing we rip out is SMPS

[xman737]

Originally posted by wytco0
Just noticed that there are more picture of the new power supplies on the hypex site at New Hypex Power supply pictures

The capacitors used seem to be BC compoment 63 V 10,000 uF. Is 63V too little for UcD 400?