Stage Lighting? Certainly not going to be old style LED's. The super bright LED I just tested had no problems with 24V reverse volts.

I agree with your caution, especially with old red LED's. But we're not dealing with old red LED's.

I'm still trying to find a reference that would give an idea of what LED reverse current breakdown voltages are. But since the resistor is dropping so much voltage the reverse shouldn't be anywhere near breakdown.

The test could be done with SIX volts AC and 100ohms and it would be safe for all.

 

The test could be done with SIX volts AC and 100ohms and it would be safe for all.

VERY true. All I have for AC is 24VAC. However, testing at 6V 100Ω with a Vf of 2.0V still runs 40mA through the LED. 500Ω would be better since all you want to do is light the LED. That should be around 8mA, enough to light the LED and not burn it up. 250Ω would result in 16mA, making any LED bright enough to be seen in ambient light conditions.

The key is testing with AC prevents accidentally testing with the wrong polarity and coming to the wrong conclusion.

 

And now we're off topic.

Back to the basic poser - did the TS test with the correct polarity on the LED's? Since ALL LED's showed being dead - that's a HUGE pickle to swallow in one gulp.

 

REally, the big question is about the specifications of the new panels. How do those specs differ from what the drivers want to deliver??? OR, are they somehow the same??

 

94/35 = 2.6V (new board)
94/45 = 2.1V (old board)

The second is about the right voltage for amber LEDs of that type. 2.6V might be right for higher power amber LEDs.

It is a bit of a puzzle that all 45 LEDs would blow at the same time without obvious physical damage.

I presume you checked the LEDs with both polarities, right?

Yes, I did check last night, with both polarities. (to be clear so I don’t confuse yall, I used a Radio Shack multi-voltage wall wart, set to 4.5 volt setting—next step was 6volts—along with the resistor MrBill mentioned before.) I then turned the old panel over, lamps down, and then touched the positive probe/resistor to the first leg of an LED, the negative probe on the other leg. I started this on the first LED of each loop and went to the end. I’m assuming that if any had lit I could see some result. I did that to the backside of the new board on a couple, and could clearly see the light underneath…Like you and the others, I just can’t get a grip on how all would be bad at the same time, unless there was something wrong with the inbound power connector. But again, I tried the other three panels on this connector/string, and they all worked fine.

 

Wondered the same thing. THAT inspired me to imagine a 24VAC source with a 1K5 resistor. 16mA shouldn't hurt an LED. The reverse voltage shouldn't cause any problems either. And regardless of the polarity the LED will still light.

Going to test this in minutes.

Yes, I did try flipping my power leads around and no difference.

 

REally, the big question is about the specifications of the new panels. How do those specs differ from what the drivers want to deliver??? OR, are they somehow the same??

You lost me on this one—I’m not sure what it is with the “drivers want to deliver”

 

Stage Lighting? Certainly not going to be old style LED's. The super bright LED I just tested had no problems with 24V reverse volts.

I agree with your caution, especially with old red LED's. But we're not dealing with old red LED's.

I'm still trying to find a reference that would give an idea of what LED reverse current breakdown voltages are. But since the resistor is dropping so much voltage the reverse shouldn't be anywhere near breakdown.

About the “stage lighting”…this original set was purchased new about 2009. And on this same panel it also has one of the panels with one loop out (Now I want to pull it back out and probe that loop on back of that panel) and I think the green panel has some out, in the same loop. But not every one. I want to look at that one too. LOL…just to satisfy my curiosity, even though I’ve decided to just relamp the bad panel and see what happens.
On another note, this new bank of lights is so typical to me—they look to be cheaper made, smaller overall and lack the function of being able to hook up a floor switch panel to change scenes. They’re pretty cheap though, at 65 bucks per unit. One unit for each side of stage, powered by extension cords, and switched by using a built in microphone for single sequential lights, or flip an onboard switch to light up all. I guess that’s why they call them “DJ” lights—only lighting up one person.

 

[edit] ignore the followng , I posted to the wrong thread.
It's just a drawing. One of the two coil wires is connected to positive and the other to negative. Since it's a horn relay it's unlikely I'll ever be replacing it with anything other than a generic relay without diode. And if I DO put one with a diode - I'll blow the fuse quickly.

 

As far as the reverse breakdown issue goes, keep in mind that there is not much voltage drop until current flows, and with reverse breakdown, once the breakdown happens it does not matter much about the current because the damage is done.

 

I took another look at things today. Rechecked the original problem panel again with power supply. Nothing mad any LED react. But any other panel and even the new full panel, all worked fine when touched with the power supply probes. On the original Bar, the Green panel had a few out, so I took it off and looked into it. One LED was actually bad in one string, and in another string it ended up being a finicky solder joint around the main connector. I stuck a clear-ish LED in that bad one spot, and all of that panel came back to life. I can see now these things are so finicky…
Replacing those 45 lamps in the original panel will be a real pain for me—I tend to shake a lot more these days…I’m sure there will be some screams and some bad words…lol

 

One broken link in the chain and the whole thing doesn't work.
Pay VERY CLOSE ATTENTION to polarity. Get ONE backwards and again the whole thing won't work.

 

Whew! I received the replacement LEDs yesterday and last night cleared off the old ones. Then I set out to check all the traces, holes, etc. All were fine except one—I believe the fault is where it gets its positive input from the onboard connector—but it appears to be UNDER that connector where the fault lies. I could possibly jumper it—unsoldering that connector is three simple legs, but SO tiny, even for my needle iron. Getting it back on with no shorting could be a real mess for me. But my curiosity always gets me and I need to know—WHY is this connection not happening. So I will attempt to desolder it and take a look. Worst case scenario I might have to hardwire the connection in some manner.
And THEN, it’s on to putting in those 45 lamps…I dread that LOL

 

Certainly the difficult part of the project will be removing the present LEDs and making the holes ready for the replacements. I suggest verifying the correct polarity several times during the installation. And possibly not trimming te leads until the correct polarity has been verified.

 

Certainly the difficult part of the project will be removing the present LEDs and making the holes ready for the replacements. I suggest verifying the correct polarity several times during the installation. And possibly not trimming te leads until the correct polarity has been verified.

“Making ready” is done…well, except I need to find why that one string isn’t getting power to the first hole…so I guess I’m really “not ready” LOL…I forgot about that little tidbit for an instant…
Yes sir, knowing me, no matter how careful I think I am, I usually end up forgetting a part, screw, or something backwards. Never fails. I’ll have to come up with a better plan this time…

 

You shouldn't have to desolder the connector if you can jumper the leads to where they go. It would seem to me that there's a faulty trace or fractured solder joint.

 

You shouldn't have to desolder the connector if you can jumper the leads to where they go. It would seem to me that there's a faulty trace or fractured solder joint.

Yes, I guess that would be the smart thing to do, and I’ll tamp down that “curiosity” thing I get a lot.
Come to think of it, I was messing with the whole thing a few nights back when I fixed one string of greens not working, then noticed all the blues were working instead of one string being out too. I guess it has a faulty trace too but for now it’s good.

 

BRING IN THE TRUMPETERS! SOUND THE CELEBRATION! SUCCESS!!
The amber/yellow 45 LED panel has been re-lamped and now lights up. I should have my head examined, making it so difficult, and yet simply replacing the LEDs took care of it. I guess I’ll never change. (If you don’t veer off the main highway sometimes, you’ll likely miss a lot of interesting sites. )
Many thanks to all of you for venturing down this “backroad” with me.

 

BRING IN THE TRUMPETERS! SOUND THE CELEBRATION! SUCCESS!!
The amber/yellow 45 LED panel has been re-lamped and now lights up. I should have my head examined, making it so difficult, and yet simply replacing the LEDs took care of it. I guess I’ll never change. (If you don’t veer off the main highway sometimes, you’ll likely miss a lot of interesting sites. )
Many thanks to all of you for venturing down this “backroad” with me.

Wisdom is not doing the same wrong thing three times. You have acquired wisdom.

 

BRING IN THE TRUMPETERS! SOUND THE CELEBRATION! SUCCESS!!
The amber/yellow 45 LED panel has been re-lamped and now lights up. I should have my head examined, making it so difficult, and yet simply replacing the LEDs took care of it. I guess I’ll never change. (If you don’t veer off the main highway sometimes, you’ll likely miss a lot of interesting sites. )
Many thanks to all of you for venturing down this “backroad” with me.

OK, and now a question: How many of the LEDs were failed?? I wonder about that.
I am asking to see how common multiple LED failures actually are. I have a large stack of dead LED tubes, and of those that I have opened and checked, several have had multiple failed LEDs in each segment of 24 surface mounted LEDs. And since they seem to be glued down they would be a challenge to replace..