PWM BNC Stray voltage

[Toolboy]

HI

Having an issue with stray voltage that I just cant figure out. I've got a std reef angel with a pwn addon unit. and standing barefoot on my tiles

Ive managed to track it down to something to do with the ELN drivers and the ph probe. If only the power to the drivers is connected. The pwm unit is not powered only the USB cable to the powerbox, and the ph probe is in the water. If i put my hand in the water i feel current. Even when i take the probe off the BNC connector and touch it without touching water i still feel current. And obv if there is no power on the ELN drivers the probe/BNC dont have that current on them

So some how power is traveling between the PWM unit through the USB cable to the plugbar then through to the Ph BNC/probe

Ive had this problem ever since I went LED with the PWM unit, so Ive been pulling my hair out trying to figure this out for over 6months now

Can anyone see what Im doing wrong as I doubt its the RA stuff otherwise this would have happened to many other ppl before

[rimai]

I've heard of this before. It does come from the meanwell drivers.
Interestingly enough, not all drivers have this problem
So, I'm not so sure what they did on their drivers that some have and some don't.
It happens because the entire system is using the same DC ground.
The newest dimming module revision has a built-in opto-isolator to break this DC ground sharing.

[Toolboy]

Thanks Roburto.

Cant say im overly pleased about the news. My only option would then be to move over to the LDD type drivers which shouldnt be a problem except my pwn unit outputs 10v and LDD uses 5v. If i understand it correctly. Without having to buy another a new pwn unit is there any way to get my pwn unit to work with LDD drivers

Or do you know of a different idea

[rimai]

With the new dimming module, you would be able to still use your current LED system.
The opto-isolator breaks this DC ground sharing and the stray voltage won't travel through.
Besides the opto-isolator, you also get the ability to change signals. It comes with user changeable jumpers that you can use to change the signal type of each channel individually. So, you can choose to have any of the 4 choices in each channel: 0-10V PWM, 0-5V PWM, 0-10V Analog, 0-5V Analog.
But, if you do decide to move to LDD and still want to use the old dimming module, we can also make it work.
You would need to unmount some SMD components from the pcb board though, or send it back for me to do it.

[Toolboy]

Good news that I can still use my current unit. Im no electronics boffin. More likely to burn through the board than anything else. Luckily my brother in law does electronics if you could send me instructions and whatever else one would need to do this ill ask him if he can do it otherwise ill send it to you

[rimai]

Can you let me know what revision board you have?
Open the case and it should be written in the board.

[Toolboy]

No problem. Will do it for you tomorrow

[Toolboy]

I have pwm expansion 2.1

[rimai]

Remove R1, R4, R8, R10, R12, R14
Short out the pads of the resistors you took out.
It may be possible to create the short even without taking the resistor off, which is ok too.