COB build flickering again..

[heckler73]

When I turn the multimeter to the 2k ohm setting it reads 1. When I touch the + lead to the + on the led and the - lead to the - on the led it still reads 1 on all 5 cobs.

Could you explain further what you are asking me to do with the pot wires?

What happens when you touch the leads together on your meter?

 

[Al Yamoni]

What happens when you touch the leads together on your meter?

on the 2k ohm setting, once the leads are touching each other it reads zero. I have a 1w chip here and if I touch it with the leads properly it lights up.

 

[heckler73]

on the 2k ohm setting, once the leads are touching each other it reads zero. I have a 1w chip here and if I touch it with the leads properly it lights up.

I think he may have wanted you to check the voltage drop across your LEDs, not the resistance.

 

[Al Yamoni]

I think he may have wanted you to check the voltage drop across your LEDs, not the resistance.

Is that a different setting on the multimeter?

 

[Al Yamoni]

If I had one of these suckers overheat and become damaged, could that be what is causing the flickering and the 35watt draw issue?

 

[SPLFreak808]

When I turn the multimeter to the 2k ohm setting it reads 1. When I touch the + lead to the + on the led and the - lead to the - on the led it still reads 1 on all 5 cobs.

Could you explain further what you are asking me to do with the pot wires?

Ok so it seems your led's are not leaking. eliminate the chips one by one and see if the flicker stops. If it still flickers then try this, Use the VDC setting( or VAC if your input is not direct current) check the power input of the driver, if the voltage is steady when the chips flicker then the power supply is good, This pretty much points to the driver.

 

[SPLFreak808]

If I had one of these suckers overheat and become damaged, could that be what is causing the flickering and the 35watt draw issue?

Yes that could cause problems, if. The led overheated, you can try measuring voltage drop per driver.

 

[heckler73]

Is that a different setting on the multimeter?

Yes...I think it is on the left side of your meter, with the big V on it.
Try turning that to 200, and put the positive lead on the positive side of the LED, and the ground on the negative part.
Read the numbers on the display.
Record the numbers by first selecting a writing implement of your choice. I would recommend a pencil.
Utilize that writing implement to scribble a happy face on a piece of paper.
Write the number you read on the meter onto the paper below the happy face.
Rinse and repeat.

 

[Al Yamoni]

I've just rebuilt the entire thing.. a faulty cob or a faulty driver? Am I wrong to narrow it down to these two just yet?

 

[Al Yamoni]

Ok so it seems your led's are not leaking. eliminate the chips one by one and see if the flicker stops. If it still flickers then try this, Use the VDC setting( or VAC if your input is not direct current) check the power input of the driver, if the voltage is steady when the chips flicker then the power supply is good, This pretty much points to the driver.

Ok, will do! Thanks for the details. I really hope it's just one of the cobs at this point..

 

[heckler73]

I've just rebuilt the entire thing.. a faulty cob or a faulty driver? Am I wrong to narrow it down to these two just yet?

What do you know? Did the situation change when you "rebuilt" it?
Have you tried changing the wiring order of the chips?
Do you have voltage readings? I'm afraid to tell you how to read current.

 

[Al Yamoni]

Yes that could cause problems, if. The led overheated, you can try measuring voltage drop per driver.

Can I just wire the cobs to the driver one at a time to test, or do I need to wire more than one because of the power of the driver?

 

[Al Yamoni]

Yes...I think it is on the left side of your meter, with the big V on it.
Try turning that to 200, and put the positive lead on the positive side of the LED, and the ground on the negative part.
Read the numbers on the display.
Record the numbers by first selecting a writing implement of your choice. I would recommend a pencil.
Utilize that writing implement to scribble a happy face on a piece of paper.
Write the number you read on the meter onto the paper below the happy face.
Rinse and repeat.

The voltage readings were all slightly different negative numbers -.3to-3

 

[Getgrowingson]

You have the positive lead to positive side of the chip and the negative lead to the negative side of the chip?

 

[Getgrowingson]

You should have +36v or +72v across each led when powered on. If you have the leads on the right sides you shouldn't have negative voltage and you definitely shouldn't have only. 3v

 

[CanadianONE]

If you want to test the voltage drop across each COB turn you multimeter to the diode setting bottom right.

 

[FranJan]

The voltage readings were all slightly different negative numbers -.3to-3

If you're getting negative numbers when testing your circuit without the driver connected that probably means you have it wired wrong or you're shorted to the heatsink. Take your probes and place them on your heatsink here and there. If you're getting readings after a moment you're shorted to the heatsink somewhere.
Pictures Al, pictures please.

 

[Al Yamoni]

If you're getting negative numbers when testing your circuit without the driver connected that probably means you have it wired wrong or you're shorted to the heatsink. Take your probes and place them on your heatsink here and there. If you're getting readings after a moment you're shorted to the heatsink somewhere.
Pictures Al, pictures please.

when testing the cobs I only get readings of 1. When I place the leads on the heatsink I get a reading of zero.

 

[Al Yamoni]

You have the positive lead to positive side of the chip and the negative lead to the negative side of the chip?

Yes I do.

 

[Al Yamoni]

You should have +36v or +72v across each led when powered on. If you have the leads on the right sides you shouldn't have negative voltage and you definitely shouldn't have only. 3v

On which setting?