Pixie 16 Logical Resolution

[cdlouke]

Pixie 16 has been eating power supplies on a 16x100 tree. Trying to figure out what is going on.

Updated firmware to .07.

Resetting configuration and can't remember correct setting. The Logical Resolution should be set to 100 and 100 pixels per port???? Or is it 50 and 100 per port.  If that is not right what is?

Thanks Charley

[Mr. P]

Logical resolution should stay at 50.

[k6ccc]

Can't help you on the logical resolution part (Ah, I see Mr. P just did), but what do you mean by:

7 minutes ago, cdlouke said:

Pixie 16 has been eating power supplies on a 16x100 tree. Trying to figure out what is going on.

Do you mean that you are having power supplies fail?  What is the power supply (or supplies if two)?  How many pixels are being powered?  Are you running the pixels at 100% brightness?

 

[cdlouke]

Thanks Mr. P, this old brain of mine was having a brain melt down. 

Jim, I am running 16 strings of 100, with 2 350 watt 30 amp supplies. I blew 2 that had been in use for 3 years, replaced them and they went in a day. Rewired and tightened all of the connections and checked to make sure none of the wires had gotten frayed. So before I fire this thing back up I am just trying to cover my bases. 

[k6ccc]

17 minutes ago, cdlouke said:

I am running 16 strings of 100, with 2 350 watt 30 amp supplies.

So, 800 pixels per 12 volt 30 amp (actually 29 amps) power supply.  Let's do the math.  At full 100%, each pixel draws about 55 - 60 mA - or 0.055 to 0.060 amps.  Using the low figure, with 800 pixels at 100%, that comes out to 44 amps.  See a problem?  That BTW is one advantage to 5 volt pixels as opposed to 12 volt pixels.  The current draw is still the same 55 - 60 mA per pixel, but the "standard" 350 watt power supply at 5 volts is a 70 amp supply.

Note that this applies to standard pixels.  There are also low power pixels that draw about half that current.

My general rule of thumb is that a 350 watt 12 volt supply can handle about 400 pixels and if using 5 volt pixels, a 350 watt 5 volt supply can handle about 1,000 pixels.  My pixel tree and star is 2,870 pixels all at 5 volts.  I have four 350 watt supplies for the tree.  I also always assume 100% full white for power supply and fuse calculations even if I expect to run at lower brightness percentages.

 

[TheDucks]

While lots of people (and LOR and others RTG units) run their supplies INSIDE a GG1500 (or similar) case, I question the temperatures during operation.

350W @ 85% efficiency = 58W dissipated inside the box plus whatever the controller does. (I remember my sisters 'Easy Bake' oven. A 100W light bulb baked cookies.)

Also consider Ambient (around the box. Canadians and Alaskans probably do not need to worry 😛)

If your spares have been laying around for years, the Capacitors may have needed to be 'reformed' (at least, old electrolytic's did) and not slammed into full load applications right away.

[cdlouke]

Thanks Jim, I see your point. I am way underpowered. I guess I have just been lucky running it in past years.

[dibblejr]

NEVER Change the Logical Resolution from 50 unless you know what the results will be.

You will have a bad experience if you do and are running pixels as most normal users do.

JR