UcD400 Q & A

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#301
I have only one rectifier, I screwed it to the (steel) floor plate and have not encountered any trouble yet.

I just returned from Hypex where they checked my broken module.
It seems (however, I have no recollection of that) that I have mechanically (so by a little force) ruined a zener, which makes a 15V regulated. So the part that uses that 15V, received 56V and could'nt handle that: fireworks.
They will try to make it work again, but gave me another one for the time being.

Thanks Hypex!! I love it that I live in Groningen!

JP, I will get to you (mail) how to work this out financially.

Frans
 
#303
dunky29 said:
Hi,
I'm a french guy very interested by this sweet module.
I've a toroidal transfo of 400va 2x30VAC and 4 capacitors of 10000µF 63V.
What power could I have with this component?
Click to expand...

Output power is P=Vrms*Irms, with Vrms= R*Irms (Ohm's law ; R=speaker impedance)

So power can be expressed either as:
Vrms^2/R or R*Irms^2

Due to 60V rail overvoltage detection Vrms can not exceed 60/root(2) which is about 42V AC (note that's at high line condition, so nominal transformer voltage should be 10% lower i.e. it should not exceed 38V AC)

There is also a 15A overcurrent detection so Irms can not exceed 15/root(2) which is about 10.6 A AC

So max power is in fact min ((60/root(2))^2/R , R*(15/root(2))^2), i.e:

Pmax(UcD400)= min(1800/R, 112.5*R)

Examples:
R = 8 ohms -> Pmax = min (225, 900) = 225W (voltage limited)
R = 4 ohms -> Pmax = min (450, 450) = 450W
R = 2 ohms -> Pmax = min (900, 225) = 225W (current limited)

For the transformer you mention VrmsMax is 30V (transformer voltage), so max power would be 30^2/R = 900/R (e.g. 225 W for 4 ohms, 112.5W for 8 ohms) : in this case power is clearly limited by your transformer voltage.
 
#305
chrisb03 said:


Does the rectifier or bottom plate ever get warm or hot? I have changed layout based on your setup, that is, mount rectifier on bottom plate.

Chris
Click to expand...

Nice, but while you're at it you might as well draw individual wires, it's not clear if you have a star ground (center of star should be at the center of your PS PCB IMHO).
 
#306
nickywicky said:

(I also tried 6 of these sleeves end on end covering the entire cable.)
Click to expand...

(In case your problem hasn't been solved yet)

It just occurred to me that uneffectiveness of the ferrite sleeves could point to a common mode RF signal on your speaker wires. In this case making your earth connection at the audio output ground level should suppress the RFI.
 
#307
Golgoth said:


(In case your problem hasn't been solved yet)

It just occurred to me that uneffectiveness of the ferrite sleeves could point to a common mode RF signal on your speaker wires. In this case making your earth connection at the audio output ground level should suppress the RFI.
Click to expand...


I'm pretty sure the problem will come down to one faulty module. I have 3 modules; one had no EMI problem, one had a small issue but the ferrite sleeves did solve that one. The 3rd one can even have the speaker cable to the module totally disconnected (so there is no speaker cable) and be inside a metal case and still creates EMI. We'll have to wait for the shipping time from NZ->Netherlands for confirmation of this though.
 
#310
chrisb03 said:



Not sure what you mean by star ground. Are you refering to the zero volt rail?

Here's a link to the lcaudio predator which my circuit will approx be base on.
Click to expand...


The idea is that all your power grounds are connected to a single centre point, in a star like arrangement, rather than in bus schemes, to avoid tiny voltage differences induced by ground currents running along the buses.

I don't know how critical star grounding is for the UcD, nor where the star center should be located ideally, maybe JP or Bruno could answer this?
 
#312
timo,
OK good to hear he is still around, I miss his input in the forum, Bruno had a lot to do with getting the Class D section setup and he has made many interesting posts.

I guess its takes a lot of time and he is busy.

Tim aka wytco0
 
#314
c4d, absolutely, but ....

I have spent 25 years working in computing and I have a good scientific understanding, however I do not know much about electronics, many of you who are expert at it have probably forgotten how hard it can be for a beginner, even a knowledgeable beginner, to sort out the important bits from the irrelevant, in my view Bruno is excellent at it.

Anyway I think I have digressed more than this thread needs 🙂 🙂
 
#315
Hi,

I certainly havent' forgotten, I'm nothing more than a rank amateur. I'm sure I've asked some of the dumbest questions on here (if there's ever an award)..
I've also very likely unintentionally repeated some of them at one point or another..

So I sure wasn't trying to point any fingers!

These are also very fast moving high activity threads and people dont' want to take the time to read the information already in them, most of which admitt so at the beginning of their post.

Yet, if they can't take the time to read the thread, why would Bruno or anyone else want to take the time to answer the same question for the twentieth time? It'll chase them away and we sure don't want that!

Anyway I won't post about that again, burning my soap box, it's off my chest 🙂

I love the level and quality of help and information available here, just want to see it continue, it is unmatched anywhere.
 
#318
OA51 said:
Is there a "maximum'" limit of PSU capacitor size, i.e 100000µF/rail or whatever, where the sound quality of the UcD400 will start to degrade?
Given that you use a suitable transformer...

-like with the chip-amps...

/Stefan
Click to expand...


I'm also interested in the answer to this question. I have made a couple pcbs with 27200uF on each rail. I'm a bit worried that this may have a "bad" sonic difference. The capacitor banks are my last bits to go into the enclosure installation. I'm just holding off incase there is a problem with capacitor quantity.

I've also changed the layout. I have attached new pics if anyone interested.

Chris
 
#319
Chrisb03, I think Bruno said something about this on the UCD180 thread and someone else referred to it recently, so if you go to the end of that thread and work backwards you should find it.

I notice you have a load of what I think are called snubber caps in your power supply, why have you included them?
 
#320
Hi,

I know, it's not my competence, in my humble opinion it would be better to avoid mixing the themes between the threads. I would kindly ask you to discuss these supply problems in the appropriate thread. It will be easier to find any special information later, not only for me.
Thank you very much indeed!

For minimum capacitor requirements see Bruno's post. I for myself do not see any disadvantage for too big rail capacitors, except overkill and inrush current without a softstart circuit. :redhot:

Best regards, Timo
 
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