COB build flickering again..

heckler73 · Sep 26, 2015

Al Yamoni said:
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 · Sep 26, 2015

heckler73 said:
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 · Sep 26, 2015

Al Yamoni said:
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 · Sep 26, 2015

heckler73 said:
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 · Sep 26, 2015

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 · Sep 26, 2015

Al Yamoni said:
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 · Sep 26, 2015

Al Yamoni said:
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 · Sep 26, 2015

Al Yamoni said:
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 · Sep 26, 2015

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 · Sep 26, 2015

SPLFreak808 said:
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 · Sep 26, 2015

Al Yamoni said:
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 · Sep 26, 2015

SPLFreak808 said:
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 · Sep 26, 2015

heckler73 said:
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 · Sep 26, 2015

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

Getgrowingson · Sep 26, 2015

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 · Sep 26, 2015

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

FranJan · Sep 26, 2015

Al Yamoni said:
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 · Sep 26, 2015

FranJan said:
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 · Sep 26, 2015

Getgrowingson said:
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 · Sep 26, 2015

Getgrowingson said:
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?

COB build flickering again..

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