LED power supply

[diif]

Hi Badcappers, I'm after some advice.
I've installed LED strip lighting in my office/workshop, it comes in 5m lengths and i've been powering it off my bench power supply. A 5m length is drawing 2.42A and when i had 10m attached in parallel i've noticed the outputs of my power supply get quite warm/hot.
I decided i needed a proper driver and bought a R-200-12 a 12v 16.5A LED power supply as it seemed as it would have some spare capacity.

Obviously i opened it up as the QC inspected sticker was already broken.

Dongbaohe and Twco caps inside, (i've never heard of Dongbaoe)

I was going to connect the wires from my ceiling light to the L N and earth and connect 3 or 4 5m lengths of the LED strip in parallel to the V+ and COM.

I guess the voltage pot is then adjusted to 12v ?
Am i correct in my way of connecting and setting this up.
Should i replace those caps ?
Thank you.

[ReeceyBurger123]

Re: LED power supply

I have a similar set up, I also use a similar Psu its normal for it to get hot you dont need a driver for those Leds either which is why they are in groups of 3 (4v per Led = 12v) Also yes replace them output caps cheap junk brand. Also make sure to heatsink them Leds ! They get very hot and will fail in no time flat.

[mariushm]

Re: LED power supply

The psu seems to be of decent construction, they use bridge rectifier, they use proper switch for 110/220v, proper Y capacitors for filtering, common mode choke and x capacitor for mains filtering..
The large capacitors aren't subjected to that high currents and ripple, they should last even though they're noname.
The secondary capacitors, feel free to change. You'll increase the reliability. Too bad there's no footprint for additional inductors.
The only other component that you may want to improve would be the D4 diode pack (higher current and voltage) but the one should be rated properly and work properly if it's attached to the case or heatsink.


The voltage pot is there to allow you to adjust the output voltage between something like 10.5v and 13.5v

Your led strips are basically a whole bunch of tiny sections of led strip, each section has a few leds (usually 3) and a resistor to limit the current.
For example, let's imagine 3 leds and a 150 ohm resistor. Assuming 3v drop per led, we have 12v - (3x3v) = I x R , so I = 3v / 150 ohm = 20 mA per led.
Of course, if you power the led strip from only one side, by the time the traces reach the last segments, there's going to be some voltage drop and the last segments will see less than 12v but the leds will still light up. If you want as uniform lightning as possible power the strip with 12v from both ends.

So with more voltage given to the strip, each section will light slightly brighter and the resistor will dissipate a bit more heat. Usually the differences are small.. I'd say just tweak the output to 12.3v or something like that, to account for the voltage drop on the cable between the psu and the strips.

[diif]

Re: LED power supply

Ahhh, the LEDs are mounted onto PVC pipe at present. About 28c. Barely warm.

I've checked the specs of my power supply and its 10A so think the warm connector is due to to the cheap crapness of the banana jack plugged into it.

Thanks for the explanation mariushm.

The diode is marked MBR 30100 H90. There is thermal paste then an insulating sheet with a clamp pulling it onto a heastink.

[ReeceyBurger123]

Re: LED power supply

Probably is the issue, will link video to my set up:

https://m.youtube.com/watch?v=JQjCOH1Robk

Upgrade of the Psu:

https://m.youtube.com/watch?v=PXWJFNX2QBk

[diif]

Re: LED power supply

I was taking the connection on my bench PSU.

[stj]

Re: LED power supply

now THAT is how a psu should be!
caps as far from the heatsink as possible.
i wouldnt be surprised if that ran for many years even with the chinese caps.

[ReeceyBurger123]

Re: LED power supply

They are actually decent Stj you can get them off ebay for cheap. The chassis is the heatsink for the power devices.

[diif]

Re: LED power supply

The Chinese caps have now been replaced with FCs.
It was £12.99 for 200W. Maybe a bit overkill.

[diif]

Re: LED power supply

Finally finished. Excuse the mess.

There will be some some LED lights on flexible arms coming later when they arrive.

[diif]

Re: LED power supply

Well it seems the magic smoke has escaped.
R17 has decided to take a vacation.
Nothing was being touched or played with.
I had the voltage turned down to about 10v.

Can anyone shed any light on why it blew ?

[stj]

Re: LED power supply

not without knowing what it connects between

[diif]

Re: LED power supply

not without knowing what it connects between

Would a better photo of the back help ?

Or do you mean what it was powering. Three 5 meter strings of LEDs. Well one wasn't quite 5m whih is why i had he voltage down a little.

[stj]

Re: LED power supply

oh i see - it's across Q1
if Q1 looks o.k. maybe it couldnt handle the pulse-current.
is the small vertical driver board o.k.?

[diif]

Re: LED power supply

Cheers stj, yes the little board looks ok.
Q1 has a short. It's an 8N60.

[ReeceyBurger123]

Re: LED power supply

Blown already wow did you have thermal paste on it ?

[diif]

Re: LED power supply

Blown already wow did you have thermal paste on it ?

Yes, i put fresh on it when i recapped it. Does look like a generic China special, as there are no logos on it.

Has running this at a lower voltage shortened it's life or have i just been unlucky ?

[ReeceyBurger123]

Re: LED power supply

I dont think so as the feedback circuit would adjust to what you lowered it too. Probably too much load on start up or something. Maybe get another and build a protection relay board so that the Psu starts then the relay does then the Leds ?

[diif]

Re: LED power supply

Cheers Reecey.

The lights had been on for a couple of hours so i don't think it was a start up load issue.

[ReeceyBurger123]

Re: LED power supply

Ahh right, thats odd maybe it wasnt screwed to the frame tight enough as it doesnt look to firmly pressed against it and overheated ? Or maybe the transistor broke though the solder joints causing it to blow ?