Led4power.com : LD-4 CC linear drivers, ILC-0/1 illuminated tailcaps, optics, MOSX, copper DTP MCPCBs...

You only drill the X6 shelf enough to fit the bolt so head of the bolt presses on the bottom of LED shelf. The inside of the spacer is threaded so it grabs onto that and pulls spacer toward top of LED shelf

With hollow bolt method assembly is much easier because once you install spacer with bolt and tighten it, spacer cannot move or spin because clamping force is big which is also good for thermal transfer between spacer and body. After that you can easily install mcpcb and driver.

With traditional spacer this is more complicated/messy since everything is loose and can move - source of clamping force is bezel (force "travels" through optics) - not optimal IHMO.

Hello!
I bought some of the last ld-b4hv, but I have a problem with the gate solder pad coming off the pcb. Happened on two different driver boards while I was soldering.

Figured I could solder the wire on top of the resistanse in the photo because it looks like they are connected (measured for continuity on a third driver board which I have not done anything to yet).

Google Photos

Then something strange happened.

I’m using the mosx board with FET. When I measure for continuity without wires attached I have connection through the LED between + and “m” and no connection between + and -

Google Photos

As soon as I connect the gate to the mosx the FET is shorted out and I have connection between + and - even when the FET is not energized.

What is going on. Is my point for gate on the driver wrong?

The third picture I have attached (this is something led4power posted earlier in the thread) - why is there a wire on the m pad ?

Google Photos

I never had problems with pads coming off pcb, it seems you are using way too high soldering temperature, do you have any pictures of your soldering work?

You can solder wire to those resistor pads, but be careful, if you are holding soldering tip for too long or temperature is too high, you could easily desolder/remove resistor since it's very small.

Which mosX board and which 6V LED are you using? "M" pad is connected to LED cathode. There should be no continuity between + and M, maybe you've soldered LED rotated by 90deg? You should check LED and MCPCB first, of course driver can't work if LED pads are shorted.

In third picture is Luxeon MZ (3V LED) driven by LD-B4 driver (not LD-B4HV which is >1S driver), LD-B4 has moonlight support so M wire is for moonlight modes.

Thanks for quick reply! :slight_smile:

My soldering is probably the cause :slight_smile:
I’m using a regular 25-30W soldering iron without temperature control. Heating the wire/pad until the solder is melted and then let go.

I might have soldered the LED wrong also, but if M is connected to LED cathode there should be continuity between “+” and “m” on the mosx when measure through the LED? Like in the photo:

Google Photos

Don’t know if this is usual, but the LED lights up when I use my voltmeter on continuity setting so I know the LED is working at least. Just like in the picture when I measure between + and m.

And at first I did connect battery and all and discovered I wasn’t able to adjust brightness or enter setup mode. The LED was running direct drive I guess. Luckily the battery wasn’t full and I jused just thin wires to test with. It was bright :smiley: :smiley:

The LEDs are a XHP70.2 6V on the mosX connected in series with a XHP50.2 6V on separate pcb. Driven by 4 samsung 18650 batteries in series. The driver is the 4s/6A version.

The curcuit seems to be fine when the gate wire is not connected between driver and mosx. When this wire is connected it seems like the FET is shorted or connected somehow, like this:
Google Photos

Try to measure exact resistance (instead of continuity) between + and M pads, with LED should still see high resistance. Best way to set LED is to set multimeter to diode test, if LED is ok it will emit some light, but that usually only works for 3V LEDs.

Since you are running 2 LEDs on separate PCBs, how did you connect those PCBs? Diagram for one LED looks ok.

Ok, thanks again!
Will see when I get home.

Btw when I say continuity I mean diode test. Sorry :slight_smile:

Added the other pcb/LED to my scheme :slight_smile:

Google Photos

This other LED did come on sinkpad pcb. It’s only the XHP70 og mosX i did myself.

Measured resistanse between + and M. Even at 20M it is out of range.

Tried new driver. Soldered gate very carefully :slight_smile: went ok.

Same result though when I have my meter on diode test and measure between + and - on mosx the LED lights up as if the FET is on.

Adding some pictures. Is it possible the LED itself sit wrong on the pcb allthough I cant measure any shorts?

The driver
Google Photos
Google Photos

MosX
Google Photos

From led4power website to see how the pads look
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XHP 70 datasheet shows what is anode and cathode
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I followed this video on how to flow the LED onto the mosx. Only difference was that I did it in the kitchen using an old frying pan (don’t use it for cooking anymore :wink: ).

Used low temperature solder paste. I don’t think the solder on the fet melted while I did it.

So your FET is in series with two leds? Does it get the right voltage to function?

Yes it is. Input voltage on the driver is 16V. Two series LEDs in series.

Maybe I should switch them around so the mosx is closest to ground?

But this was my next question: do I need to hook up the battery for the FET to function? I thought it was normally open curcuit. A bit scared to power on after yesterday when I think it was direct drive…

mosX board should be last in chain from battery + to gnd (or closest to gnd), so if you connect it like in diagram it's not good.

Cool. I’ll try :smiley:

FET is normally open (high resistance) but if gate pin is free floating it can be charged for example via testing with mulitmeter and FET will be in closed (low Ohm) state for quite a few seconds even without any voltage applied to gate becasue of gate capacitance.

Actually this is the way I test mosX boards with FET: I charge gate by applying x.xV for 1-2sec, and then I connect mosX board with LED to power supply to + and - pads like standard (non mosX ) MCPCBs.

Worked like a charm! Excellent, thank you. :slight_smile: :slight_smile:

Some test fitting while I wait on LEDs

New LD-B4 12A 20MM. The pads are huge on this and easy to solder. Looking forward to finishing this build…

Finished product:

LEDs: 6x LH351D 3500K 90CRI

12A CC mode
~11.55A tail - 3,205lm

FET mode (VTC5D)
~19.4A tail - 4,370lm

Was there never a MOSLED Extreme 4*XP*? Only the black board one was made?

Yes, no 4xp mosX in 20mm size.

The black mosled should be ok with M2 quad at 12A right? Sitting on big chunk of copper

Which LEDs?