Still buzzing and flickering LED cob fixture

Problem: When at max power the LED's flicker and the driver makes a buzzing noise. If I remove a COB or dim it down then everything works great.

Things I've tried:
Removing all cobs from heat sinks, cleaned and reassembled. Checked wires.
Replaced 2 cobs that where questionable.
Removing the dimmer

Things I've measured:

• The voltage at max power on the 2 new cobs was 34 and the 2 slightly older cobs were 34.8. When very slowly turning up the dimmer I was able to get a max of about 35.3 volts before the buzzing/flickering started.
• The voltage and amps across the driver measured 152V and 2.1 amps. Which is what its rated for.
• Checked the volts from the metal cob holders to the ground wire and never got anything more than 20 mV.
• At the AC side I measured 300 watts and 118 volts at max power with all the LED's on.

Other info:
(4) 3000 K Cree CXB3590,
HLG-320H-C2100B
Fixture is a few months old
I'm stuck

Teag said:

Problem: When at max power the LED's flicker and the driver makes a buzzing noise. If I remove a COB or use the dimmer everything works great.

Things I've tried:
Removing all cobs from heat sinks, cleaned and reassembled. Checked wires.
Replaced 2 cobs that where questionable.
Removing the dimmer

Things I've measured:

• The voltage at max power on the 2 new cobs was 34 and the 2 slightly older cobs were 34.8. When very slowly turning up the dimmer I was able to get a max of about 35.3 volts before the buzzing/flickering started.
• The voltage and amps across the driver measured 152V and 2.1 amps. Which is what its rated for.
• Checked the volts from the metal cob holders to the ground wire and never got anything more than 20 mV.
• At the AC side I measured 300 watts and 118 volts at max power with all the LED's on.

Other info:
(4) 3000 K Cree CXB3590,
HLG-320H-C2100B
I'm stuck

Click to expand...

How old is the build/driver/cobs? When you run wide open without the dimmer, theres no issues?

HydroRed said:

How old is the build/driver/cobs? When you run wide open without the dimmer, theres no issues?

Click to expand...

They are a few months old. Wide open with or without dimmer causes issues.

Nothing normal about a buzzing driver. My opinion is that a replacement is in order. Even the mighty Meanwells occasionally fail.

When you measured 152V were your COBs at 35.3V?

Is your fan wired into your driver or does it have its own AC cord?

At 152V you're hitting the upper bounds in voltage for your driver. It could be just maxing out, but at 35.3V you should only have 141.2V, not 152V. If you have 152V your wiring/dimmer is eating 10+ volts, too much for either and might be a factor depending on why (unless fan run off driver?). I'm thinking you're maxing it out and it's just humming when switching at that rate but can't say for certain.

Where'd you get the driver? This is the 2nd meanwell I've heard about that is buzzing or humming within the past month or so. I think it's probably just a coil inside that's oscillating creating the noise, but idk for what reason. If you can, I'd return it for a new one and not have to worry about it again..

have you tried a different outlet receptacle in your house or possibly a different house?

I don't know much about these but i figure it's worth a shot.

You said you removed a cob and everything worked great? At max?......that would be over voltage on the build, not driver.

But like chief said 10+ volts of resistance is high, something is off

Ya your drivers got too much voltage on it. Simple as that.

ChiefRunningPhist said:

When you measured 152V were your COBs at 35.3V?

Is your fan wired into your driver or does it have its own AC cord?

At 152V you're hitting the upper bounds in voltage for your driver. It could be just maxing out, but at 35.3V you should only have 141.2V, not 152V. If you have 152V your wiring/dimmer is eating 10+ volts, too much for either and might be a factor depending on why (unless fan run off driver?). I'm thinking you're maxing it out and it's just humming when switching at that rate but can't say for certain.

Where'd you get the driver? This is the 2nd meanwell I've heard about that is buzzing or humming within the past month or so. I think it's probably just a coil inside that's oscillating creating the noise, but idk for what reason. If you can, I'd return it for a new one and not have to worry about it again..

Click to expand...

The fan is AC and not hooked up to the driver. I measured the driver when everything was disconnected. I'll do some more measuring and see if I can find where I'm losing the 10V.
Thanks for setting me in the right direction everyone! Will update unless I electrocute myself later.

So the image below shows the two different ways I measured and the measurement points.

The 142V measurement is the highest volts I can get while turning up the driver and all 4 cobs installed before the driver starts buzzing and limits(?) the volts to around 138.
This doesn't make sense to me....help.

Teag said:

So the image below shows the two different ways I measured and the measurement points.

The 142V measurement is the highest volts I can get while turning up the driver and all 4 cobs installed before the driver starts buzzing and limits(?) the volts to around 138.
This doesn't make sense to me....help.

Click to expand...

Have you tried removing the aftermarket dimmer?

Try just having the dimmer leads hanging and not hooked up, so they're creating an open loop or a broken cct. Then see if the hum persists. I'm wondering if the frequency on the dimmer (if PWM) is causing issues. Running your driver at full blast without the dimmer would rule that out. If no hum then it's your dimmer Hz or dimmer something, if it still hums then I'd suggest trying to get a new one.

When a device makes a noise its from a mechanical vibration somewhere. Somewhere something is vibrating and at a low enough Hz to be audible. This is usually a coil or some sort of inductor on the PCB, but who's to say why exactly or which one without opening up the case. It could just have less dampening material and so it's vibrating more than some of its brother components, but it could also be a malfunctioning switching cct.

Your COBs look to need ~142V total to flow 2.1A. When you're measuring V without the cobs in series you're measuring what the max V that the driver can produce is, this is different than what the the COBs need to operate per se. When measuring the current (and Io POT turned up all way) without the COBs in series you're measuring what the max current can be output by the driver.

The driver puts out a max of 2.1A, but your COBs only need 142V to flow 2.1A (35.5V each) so that's why you read 142V when COBs are installed, vs 152V when they're removed. At 152V your COBs would flow more current than 2.1A, so your driver can't produce any more V than 142V because its limited to 2.1A output. If you took out 2 of your COBs, the entire string would then only need 71V to flow the 2.1A. If you wanted to use all 152V you'd need to add another COB in the string, but then your limiting reactant isn't current, but rather V. It would take more than 152V to flow 2.1A through 5 COBs. It would take (142V ÷ 4 = 35.5V) 35.5V × 5 = 177.5V to flow 2.1A with 5 COBs.

The V seems correct now that you explain, but Id just try 1 more test before trying to get the refund/replacement.

ChiefRunningPhist said:

Have you tried removing the aftermarket dimmer?

Try just having the dimmer leads hanging and not hooked up, so they're creating an open loop or a broken cct. Then see if the hum persists. I'm wondering if the frequency on the dimmer (if PWM) is causing issues. Running your driver at full blast without the dimmer would rule that out. If no hum then it's your dimmer Hz or dimmer something, if it still hums then I'd suggest trying to get a new one.

The V seems correct now that you explain, but Id just try 1 more test before trying to get the refund/replacement.

Click to expand...

I removed the dimmer and same problem. I'll get into contact with meanwell.
Thanks for your explanation!