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CDI 2009 LED M5 Samples


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I received my samples today also. I received 5 strings of 100 ct. M5's, WW, CW, Blue, Green & Red. I tested them for quite a while on a Renard Controller running Vixen, with the following results:

Percent of intensity at first visible light

WW - 10%

CW - 5%

Blu - 15%

Grn - 5%

Red -15%

Percent of intensity at perceived full brightness

WW - 70%

CW - 60%

Blu - 70%

Grn - 70%

Red - 70%

The Red had a noticable bright flicker on ramp up and ramp down at approx. 20%

Only the Red did not have a slow fade once power was removed.

A test of a long ramp down fade on all the colors seemed more linear than the long ramp up.

I like having the PCB inside the plug ends, however, based on how the lights behave, there is still more work to be done on the circuits.

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Here is a quick update, reserving this spot for the remainder of my review to come later this weekend. I'll have more pictures and a full writeup at that time.

First of all, my initial findings support that these do have capacitors in them. See the picture in the link. Also note that these are very easy to dissect and I'll be able to restore to its original condition easily.

http://www.palombolights.com/images/led%20dissection/newm5.jpg

Fading will just not work well with the capacitors. I reserve the right to change my judgment once I get these through my tests.

I agree that caps and fading do NOT play well together.

Also, capacitors are inducing a LOT of electrical noise on the AC line or at least they do with the old CDI strings. I have a LCD TV that is sensitive to line noise and it picks up the discharge (noise) from the caps. There was no noise from the strings that I modified without using caps in them.

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This question is probably best answered by Paul. Are all the strings 100ct in the test? I am curious if Paul got samples of in the 50 ct. strings and if we will be hearing about those.

Two of the testers have mentioned they received 100ct strings. The thread that became quite lengthy about the failures was dealing primarily with the 50 ct M5 in red.

The information released so far has been very informative. Keep up the good work. I thank all of you for taking the time to test these, especially during out busy time.

Chuck

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...based on how the lights behave, there is still more work to be done on the circuits.

I'll second that!

Here's an experiment I'd love to see performed: Lift a leg of the capacitor so that it is no longer in the circuit. Then, fire up the lights to see if the removal of the cap causes any flicker in the lights. I'm betting it will not. That would prove that the capacitor - the most expensive component on the circuit board - is not needed!

I'll also bet that removal of the capacitor will allow the lights to switch off instantly, rather sloppily fading out over 10's or 100's of milliseconds.

If my bets are correct, then the cap can be totally eliminated in the production boards. Now that we've saved these "engineers" the cost of a cap on every string, maybe they can invest some of that money on properly sized resistors! I haven't had a chance to open up my burned up strings, but judging by the smell they emitted in the course of burning up, I'll bet it was an undersized resistor that burned up.

Thank you testers for all your efforts.

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Hmmm. Now that I've had a few minutes to think about it, I may have to hedge my bets. I haven't had a chance to tear open my defective strings to sketch out a schematic of the circuit. It's possible that the capacitor shown in the previously posted photo is part of a voltage doubler circuit for high lamp count strings. If so, the cap can't go away.

I'll have to think about it some more while I'm up on the roof replacing yet another failed string... :P

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Phred,

I know you have posted in the thread that I am going to give a link to. However, based on your comment about mapping out the circuit, the circuit in the previous bad strings was mapped out in this thread.

http://forums.planetchristmas.com/showthread.php?t=24389

Starting about page 17 in that thread people on this board have reversed engineered the previous lights.

Also, in your post you state the Cap could be needed in the longer strings. The longer strings say 100 ct are basically wired the same as 2 50 count but connected by wire instead of plug and sockets.

That has been my experince with lights in the past anyway. If that is the case for like a 100ct string then each 1/2 of he 100ct string would have a capaitor for it's realm of 50.

Just food for thought.

Chuck

Edited by cmoore
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This question is probably best answered by Paul. Are all the strings 100ct in the test? I am curious if Paul got samples of in the 50 ct. strings and if we will be hearing about those.

Two of the testers have mentioned they received 100ct strings. The thread that became quite lengthy about the failures was dealing primarily with the 50 ct M5 in red.

The information released so far has been very informative. Keep up the good work. I thank all of you for taking the time to test these, especially during out busy time.

Chuck

All samples were sent out as 100 count. At my end, this was the biggest problematic string. I have a request in to China about the capacitors. They were supposed to be left off of these samples but it looks as though they may have put them on. I also got some C-6 and 5MM multi color samples for a couple of upcoming shows in January. These react much better (perfect to be exact) when plugged into an outlet and uplugged. I'm thinking at this point that they don't have the capacitor's but waiting for a reply.

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My strings came Wednesday. However so did my first child (2 weeks early!) so my test time will be a little sporadic for a while.

I did plug the strings in and noticed the same thing everybody else is reporting, a significant fade off in all but the red strings. I haven't put them on my LOR setup yet, but it doesn't bode well for the red fading the same as the other colors.

As for the capacitors, in the 100 count strings, if you want a series string of 100 LEDs you have to use capacitors. The 3+ volt drop of the non-red colors requires 300+ volts across the 100 count string. The 2 volt drop of the reds requires 200V. The only way to achieve that is with voltage multiplication circuits, and the only way to do that that I'm aware of is with capacitors.

Looking at the circuit board that was posted, It looks like a voltage doubler, basically the same circuit as last years lights without the extra set of diodes (which were pretty pointless anyway). Here's the basic circuit: http://www.coolcircuit.com/circuit/voltage/vd.GIF

The actual implementation has a bleed resistor across the cap (so it discharges when unplugged) and what looks like a resistor on the input and output. The input resistor will soften the inrush to the cap when it's charging. This helps with the noise put back on the AC side. I had to add this to the refits I did for this year 50 ct. reds. AT certain fade levels, the noise they were putting out was enough to trigger the triacs on other circuits on my LOR causing other strings of LEDs to flicker, and incandescents to glow dimly. The input resistor (only 2 ohms) took care of this problem.

They could eliminate the capacitors if they went with smaller numbers of LEDs in parallel strings. Say 4 strings of 25. Of course this would require 4 times the amount of wire in each string, much costlier than a few 20 cent caps.

Lastly, I'm a little concerned that there aren't any 50 count strings to be tested (especially red) or even smaller count strings since they produced the most problems this year.

I'll post more as I get a chance to really play with them...

--Paul

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They could eliminate the capacitors if they went with smaller numbers of LEDs in parallel strings. Say 4 strings of 25. Of course this would require 4 times the amount of wire in each string, much costlier than a few 20 cent caps.

--Paul

You can break down a 100 count string to four 25 counts strings and still keep the three wires in the string. However it would then take the wiener on the wire to accomplish it. I have done this adding a additional 25 light string to a 50 light string using a small bridge rectifier, except the Red's which also takes a dropping resistor (3.3K) in series with the LED wire. I had to have 75 light strings and wanted to eliminate the receptacles and plugs from the strings.

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Hmmm. Now that I've had a few minutes to think about it, I may have to hedge my bets. I haven't had a chance to tear open my defective strings to sketch out a schematic of the circuit. It's possible that the capacitor shown in the previously posted photo is part of a voltage doubler circuit for high lamp count strings. If so, the cap can't go away.

The usual voltage doubler circuit uses two caps. Does anyone know if there is perhaps another cap at the other end of the string?

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The usual voltage doubler circuit uses two caps. Does anyone know if there is perhaps another cap at the other end of the string?

There was in the 2008 strings, so I'm assuming there is for these 2009 testers. I'll break the other end down this weekend in my evaluation.

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... based on your comment about mapping out the circuit, the circuit in the previous bad strings was mapped out in this thread.

http://forums.planetchristmas.com/showthread.php?t=24389

Starting about page 17 in that thread people on this board have reversed engineered the previous lights....

Thanks, Chuck. I was under the mistaken impression that circuit shown in that thread was just for the 50 count strings - not the 100 count strings that have been causing me so much grief.

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There was in the 2008 strings, so I'm assuming there is for these 2009 testers. I'll break the other end down this weekend in my evaluation.

I am going to breakdown the RED string this weekend, it works faster than the other colors.

I have measured the voltage across all 100 LED's it came out at 189Vdc, so there has to be a voltage doubler in there also.

Come to think about it, to eliminate the voltage doubler circuit we could power the controllers at 220Vac and not 120Vac. just a wild thought.

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The usual voltage doubler circuit uses two caps. Does anyone know if there is perhaps another cap at the other end of the string?

You're right, pshort. There must be another cap in the other end of the string. That's the only cheap way of building a voltage doubler that I'm aware of.

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The usual voltage doubler circuit uses two caps. Does anyone know if there is perhaps another cap at the other end of the string?

Yes, there is. Basically the other half of the voltage doubler. Looks the same except fot the polarity of the diode and capacitor. Same value resistors at both ends. I made a quick schematic showing what the circuit looks like. I hope it's right - I was in a hurry, you know, trying to earn a living.

LED_BLU_100CT_M5.pdf

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...The only way to achieve that is with voltage multiplication circuits, and the only way to do that that I'm aware of is with capacitors...

Agreed, Paul.

I think I'm finally getting up to speed, now. You guys check me. Are the following statements true?:

1.) The 2008 strings contained one or more under-sized resistors (wattage-wize), and this is what caused the strings to fail.

2.) In the new, 2009 strings, these resistors have been replaced with resistors with a higher power dissipation, eliminating the problem.

3.) Due to the fact that voltage doublers are employed in the higher lamp count strings, the turn-off time is excessive. But, this problem can likely be eliminated (or, at least helped) by using a dummy load at the end of the string.

Did I get that right?

I'll bet the wheels in Darrly's head are turning right now. Who wants to bet he'll be selling pre-wired dummy load plugs next season? :P

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Yes, there is. Basically the other half of the voltage doubler. Looks the same except fot the polarity of the diode and capacitor. Same value resistors at both ends. I made a quick schematic showing what the circuit looks like. I hope it's right - I was in a hurry, you know, trying to earn a living.

Let me get this straight. Did you actually disassemble both ends of a string and carefully examine it to come up with the schematic, or did you use some other method to come up with the schematic? Is it based purely on observation or on some combination of observation and supposition? Don't take this personally, it's just that I am a firm believer in starting with the basics and taking one thing at a time.

--

Phil

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My general opinion on a voltage doubling circuit is WHY? I'd rather see rectifier blobs in each end and middle of a string than work with fading issues caused by the capacitors. Sure the astehtics of the string would change slightly, but simple full bridge rectification, segmenting strings as required based on the LED count, would work best imo. Sorry I haven't posted my testing results yet, that will happen this weekend.

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Agreed, Paul.

3.) Due to the fact that voltage doublers are employed in the higher lamp count strings, the turn-off time is excessive. But, this problem can likely be eliminated (or, at least helped) by using a dummy load at the end of the string.

Did I get that right?

I'll bet the wheels in Darrly's head are turning right now. Who wants to bet he'll be selling pre-wired dummy load plugs next season? :P

If you are talking about placing a resistor across the female plug at the far end of the string, I don't think that will have much effect. The diodes pretty much isolate the LEDs and the caps that are supplying current to them from the effects of anything else on the line.

What I think is happening is that when power is removed from the LEDs there is still a charge on the doubling caps (to the tune of about 360V across the pair of caps). The 100 Ohm resistors allow the caps to rapidly discharge down to the on-voltage of the LEDs (perhaps 300V). At this point the current through the resistors (and LEDs) drops to a fairly low value. This current is perhaps 100 uA. This is probably enough current to keep the LEDs illuminated at a visible level, but low enough to take a significant fraction of a second to discharge the caps.

--

Phil

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My general opinion on a voltage doubling circuit is WHY? I'd rather see rectifier blobs in each end and middle of a string than work with fading issues caused by the capacitors. Sure the astehtics of the string would change slightly, but simple full bridge rectification, segmenting strings as required based on the LED count, would work best imo. Sorry I haven't posted my testing results yet, that will happen this weekend.

The people who make these things aren't concerned with dimming. It is a very small part of their market, and for that matter Paul's order is probably a very small part of the output of their factory.

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#1)

First, My experience with 2008 strings is only the 50-count M5 Red, Green, & Blue strings. I have not used any other color, count, or size.

The only part failing in the 2008 Red 50-ct M5's was a small surface mount resistor on the output of the male plug end of the voltage doubler circuit. If you look at Bob V's schematic (which is very close to the 2008 schematic) it would be R3. It appeared to be an 1/8 watt resistor. Replacing that resistor with the same value, higher wattage, prevented failure. I'm not 100% convinced that the overall component sizing (both power and resistor/capacitor value) was perfect for those strings. In a few tests, replacing the blown resistor with one of equal value, but higher power rating (1/4 watt) didn't result in very smooth fades. In my repairs I ended up going with a larger value resistor (330 Ohms) in that location, because I felt that it gave smoother fades. I've tried as high as 1k Ohms no performance degradation, but that is likely because the voltage doubler circuit provides more than enough voltage for 50 2V LEDs. At some point you have to worry about power dissipation as well.

So in short, yes the larger power rated resistor should prevent the same failure as witnessed in the 50ct. M5's.

2.) I haven't torn one open, but that appears to be true.

3.) A load on the female plug won't help. The female plug's outputs are simply 120AC line voltage run through the 2 wires in the string that don't attach to the LEDs. The voltage doubler circuit is split in half and takes the 120AC input at both ends, and supplies ~340V across the entire string of LEDs. To affect the discharging of the caps, you'd have to modify the circuits inside the plugs. Either reduce the capacitance or use a lower resistance bleed resistor. Both of these could impact how the circuit works in normal use as well.

--Paul

Agreed, Paul.

I think I'm finally getting up to speed, now. You guys check me. Are the following statements true?:

1.) The 2008 strings contained one or more under-sized resistors (wattage-wize), and this is what caused the strings to fail.

2.) In the new, 2009 strings, these resistors have been replaced with resistors with a higher power dissipation, eliminating the problem.

3.) Due to the fact that voltage doublers are employed in the higher lamp count strings, the turn-off time is excessive. But, this problem can likely be eliminated (or, at least helped) by using a dummy load at the end of the string.

Did I get that right?

I'll bet the wheels in Darrly's head are turning right now. Who wants to bet he'll be selling pre-wired dummy load plugs next season? :P

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Looks about right to me...

I haven't torn open a 2009 string yet, but this is the same basic circuit as the 2008's.

With a few differences. In the 08's R4 did not exist, it was shorted. There were also additional diodes on the outputs of the rectifier blobs, would have been just before R3 and just after R4. These seemed to be pointless to me in the '08 strings as they were in the rectified side of the circuit, they should never have been needed, and it appears they have now been removed.

--Paul

Yes, there is. Basically the other half of the voltage doubler. Looks the same except fot the polarity of the diode and capacitor. Same value resistors at both ends. I made a quick schematic showing what the circuit looks like. I hope it's right - I was in a hurry, you know, trying to earn a living.
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True. Probably cheaper than running 4 wires, but still more expensive than the current approach.

--Paul

You can break down a 100 count string to four 25 counts strings and still keep the three wires in the string. However it would then take the wiener on the wire to accomplish it. I have done this adding a additional 25 light string to a 50 light string using a small bridge rectifier, except the Red's which also takes a dropping resistor (3.3K) in series with the LED wire. I had to have 75 light strings and wanted to eliminate the receptacles and plugs from the strings.
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