WS2811 Technicolor Strings Have High Failure Rate

[dduck]

So it makes sense to reduce voltage on these strings.   You also mentioned you have to worry about voltage drop.
I have the 100 count 2811 TC strings and it was already determined previously injection was needed.    It would
be interesting for someone to determine how much injection is needed at some specified lower voltage level.

In the mean time I have been using 50% intensity and trying to avoid all white.    I had one bad node yesterday
out of 1600 run over a few days along with my burn-in time previously.    Now I avoid using any white at all.
Any comments on here on performing injection and lowering voltage versus lowered intensity.   

[Made2Rock]

So it makes sense to reduce voltage on these strings.   You also mentioned you have to worry about voltage drop.
I have the 100 count 2811 TC strings and it was already determined previously injection was needed.    It would
be interesting for someone to determine how much injection is needed at some specified lower voltage level.

In the mean time I have been using 50% intensity and trying to avoid all white.    I had one bad node yesterday
out of 1600 run over a few days along with my burn-in time previously.    Now I avoid using any white at all.
Any comments on here on performing injection and lowering voltage versus lowered intensity.

Here is what is know

1) The heat generated by components in these nodes is generating heat and killing itself.
2) Lower power consumption by these components will reduce the heat.

not rocket science but those are the know facts

So how do we reduce heat

1) we turn down how hard we drive these RGBs (I looked at 50% last night and it is very acceptable, so my target is to reduce everything from 100% to 50%)

2) If we use a lower voltage instead of 12 volts it should have less power to deal with for each node. We know there is a 5 voltage regulator on each circuit board. From this point on I start guessing but my guess is we need to give each node about 6 volts so the node still functions. I'm not sure how much voltage drop we will see as we go further down the string of RGBs but from my point of view about 90% of my megatree is junk so if I made it a handful of node that progress (sad but true).

So here is what I'm going to try

1) I'm using LSP and have method for reducing my sequences from 100% to 50%. The method is not working completely yet but that is goal #1
2) I need to come up with a lower voltage to run these strings on. My current power supplies are not adjustable so I'm still looking for something in the 6-9 volt range.

So that is my current path to fixing this problem (more like a bunch of dead end roads).

Joe

[dduck]

Thanks for the info.   

I have adjustable power supplies but I don't know how
much I can go down.   I may try a string tonight at 50% level and observe what
how much I can turn down the voltage for R, G, or B and observe dimming
as well as the voltage drop at the end of the string.     I already know
that 50% white is dimmed a little with a 25% voltage drop at 12V.

[Made2Rock]

Thanks for the info.   

I have adjustable power supplies but I don't know how
much I can go down.   I may try a string tonight at 50% level and observe what
how much I can turn down the voltage for R, G, or B and observe dimming
as well as the voltage drop at the end of the string.     I already know
that 50% white is dimmed a little with a 25% voltage drop at 12V.

I'm not sure how far down you can go with the voltage on the string before the string starts running into trouble but if you look at the power dissipation the LDO (voltage regulator) needs to do the formula is something like

Power - (Volt supplied to string - 5 volts) * LED current + voltage supplied to the string * current used by the LDO

The bottom line is this

1) Reduce the 12 volts and you'll reduce the heat generated by the node
2) reduce how hard you drive the LED and you'll reduce the heat generated by the node.

I've heard but have not confirmed reducing the 12 volts to 10 volts has made a lot of difference for many people. In my case most of my strings are under 50 LEDs and under 25'. At 25' the resistance in the wire is only 1/4 ohm so I might loose a volt along the way. So I'm trying to come up with 7-8 volts to drive my RGBs (but I have no idea how to generate it yet).

Joe

[Steve Gase]

So here is my plan to run 48-TM1804 100ct Technicolor strings off of 3 controllers... please shoot holes in it:

 Repeat 48 times:
 1) set buck converters to intended voltage (input=12v, output=8v)
 2) connect +12v and GROUND wires from controller to buck converter input
 3) connect buck converter output (+8v and GROUND) to string input
 4) connect DATA-Out directly from controller to string's DATA-In

 I'm inclined NOT to add power-injection.
 I'm going to test this with my bench (adjustable) power supply.

 I've not powered up any of the strings yet -- so, they are believed to be undamaged.

 Thoughts?

[tbone321]

Reducing the voltage may not have much of a positive effect.  The real issue is where is the heat coming from.  If it is just the regulator, then dropping the voltage will do well, but if the heat is actually coming from the LED, then dropping the voltage does nothing.  It seems to me that a good portion of the heat may be coming from the LED itself.

[dduck]

Steve,

Both you and I have 2.5" spacing and thus a shorter cable length and thus less resistance according to Made2Rock.
But I suspect you will need to reduce intensity and/or colors to reduce the dimming effect with lower voltage.

Bill

[Steve Gase]

Steve,

Both you and I have 2.5" spacing and thus a shorter cable length and thus less resistance according to Made2Rock.
But I suspect you will need to reduce intensity and/or colors to reduce the dimming effect with lower voltage.

Bill

I was hoping to avoid taking drastic action with the sequencing...  avoiding full-whites, keeping sequences short, forcing down intensity -- all seem very intrusive.  But... maybe that is what is needed to get through this season.  After that, I can bring things back up and have Ray deal with the consequences. 

[Made2Rock]

Steve,

Both you and I have 2.5" spacing and thus a shorter cable length and thus less resistance according to Made2Rock.
But I suspect you will need to reduce intensity and/or colors to reduce the dimming effect with lower voltage.

Bill

I was hoping to avoid taking drastic action with the sequencing...  avoiding full-whites, keeping sequences short, forcing down intensity -- all seem very intrusive.  But... maybe that is what is needed to get through this season.  After that, I can bring things back up and have Ray deal with the consequences. 

If you have the 12 volt LEDs you also have a 5 v regulator on each node. Think of it this way

you have a 1" water main going to each node on the string. At each node it connects to a 1/4" water line and that is what goes into the chip. SO your 12 volts is reduced to 5 volts before it does  ANYTHING. The reason why the strings are designed to use 12 volts is eliminate the problem of voltage drop at the end of the string. The problem came along with the design of the node not properly dissipating the heat generated.

So in Steve's case reducing the voltage going to the RGBs to 8 volts is a really good idea and should do wonders to reduce the heat generated by the node.

Look at this formula

Power = (Volt supplied to string - 5 volts) * LED current + voltage supplied to the string * current used by the LDO

and I've attached the paper that talks about Thermal considerations if you really want to get into it.

The one thing I am not sure about is just connecting the data in line straight to the string. I'm thinking the data stream will be a 12v signal and the string will be working on 8 volts. So you may want to toss a 1K resistor in line with it for starters. Hopefully someone else gave you give you better advice on this but the 1k resistor should keep you safe.

Joe

[spudman78]

Here is what I have seen running the Technicolor nodes with the 1804 chips. I ordered 3 - 100 node Technicolor strings with custom 20cm spacing from Ray on October 7th and received them on November 18th. I cut the strings into 50 node sections and installed waterproof connectors. I am running them off SSC v4 and 12v 30 amp adjustable power supplies. The output voltage was set at 12.4 volts when these nodes were burned in, inside the house. I ran them inside for about 8 hours with no problems. I put some of  them up on the house using gutter clips and ran my show for 2 nights, about 3 hours per night. Weather was dry, 30 to 40 degrees here in Michigan. On the third night, as soon as the show was started, all of the Technicolor strings had nodes that would not turn on, stayed all white, and/or stayed on as soon as they were powered up. We did have a light mist of rain during the day and temps were 40 to 45. I have several of the 1804 based nodes listed in the wiki that are working with no problems. I do have about half the Technicolor nodes indoors still and plan to run these hard for a couple of days. I know this has been a little long winded but I just want to get this info out in case it helps someone else having similar problems.

[Made2Rock]

Here is what I have seen running the Technicolor nodes with the 1804 chips. I ordered 3 - 100 node Technicolor strings with custom 20cm spacing from Ray on October 7th and received them on November 18th. I cut the strings into 50 node sections and installed waterproof connectors. I am running them off SSC v4 and 12v 30 amp adjustable power supplies. The output voltage was set at 12.4 volts when these nodes were burned in, inside the house. I ran them inside for about 8 hours with no problems. I put some of  them up on the house using gutter clips and ran my show for 2 nights, about 3 hours per night. Weather was dry, 30 to 40 degrees here in Michigan. On the third night, as soon as the show was started, all of the Technicolor strings had nodes that would not turn on, stayed all white, and/or stayed on as soon as they were powered up. We did have a light mist of rain during the day and temps were 40 to 45. I have several of the 1804 based nodes listed in the wiki that are working with no problems. I do have about half the Technicolor nodes indoors still and plan to run these hard for a couple of days. I know this has been a little long winded but I just want to get this info out in case it helps someone else having similar problems.

That seems to be the common story. It makes no sense that they work ok till taken outside and hung up. I was careful yet they developed problems shortly after being turned out. I would suggest it you can turn the voltage down that you do so.

[Hauvega]

Bring the string that is effected back inside and test again.  78L05 regulator needs 7v min to operate. It is not an low dropout regulator.  It is the 100ma version of the 78xx series.  Check the data sheets.  I get .66 watt draw on one node.

[spudman78]

I am wondering why the 1804 Technicolor nodes would require a voltage regulator and the 1804 nodes from the wiki do not? Is there a way of telling if these nodes have a 1804 chip or a WS2811 chip in them?

[tbone321]

If it is the regulator that is failing, how are the rest of the nodes behind the failed node working at all? 

[Made2Rock]

If it is the regulator that is failing, how are the rest of the nodes behind the failed node working at all?

The 12 volt line is jumper by a trace right across the board and it is the input to the 78l05. It is the output from the 78l05 that drives the node.

So as long as the circuit board itself is there you'll have the connection for the +12v and the ground side. It is the Data in line that gets passed into the chip and the chip produces the data out and that is what gets passed onto the next node.

Joe