Hi everyone ordered some parts from mountain to build my own c8 but cant get it to come on.
Driver- FET + 7135 Driver - 17mm - MTN-17DDm
Led- sst40 shaved dome
With the switch on i have 4.2v in between positive on the mcpcb and body but none between positive and negative of the mcpcb. I have continuity from positive of mcpcb and the driver spring. I don’t have continuity from negative of mcpcb and body or the outer ring of the driver(not sure if it’s suppose to or not?). When i select the diode test on my meter the sst40 lights up. Here’s a couple pics lf my crappy soldering job. Any help is appreciated thank you!
Had something similar happen with a C8 recently. Try removing the retainer ring that holds the driver in place and reinsert it. It’s possible that the outer rim of the driver is not making good contact with the host.
You’ll want the driver to sit evenly inside the smaller/deeper recess that’s right there.
Check your negative lead to the mcpcb, try shortening the lead up, keep the wire insulation on top, looks like it’s wrapped around touching the board to me???
Thanks for the replies, i shortened the leads and checked the centering/ torque of the retaining ring but still nothing.
Here are some clearer pics, the solder doesnt look that black in real life. Probably wouldn’t hurt to solder wick it all off and start over but it should still work right?
It appears that the driver isn’t centered, which would explain no connection between the outer rim of the driver and the host. Rather than re torque that retaining ring, try taking the retaining ring off, ensure the driver is sitting evenly in the lowest possible spot and then tighten the ring.
Another option would be to solder the driver into place. Although, that’s more difficult, IMO.
Here’s a picture of a similar build, same host and driver. The driver should be centered and there should be a connection between that outer rim of the driver and host.
I’ve had the same problem before. Try resoldering your wires. I use a pair of tweezers to push the wire down on the pad to make good contact. When the solder melts I hold it for another second or two. The tweezers won’t get stuck in the solder. It might be just a bad solder job not making good enough contact. Even if it looks like it. My very first build happened like that. And a couple other lights I’ve had to resolder the connections on
My bet is your retaining ring isn’t making good contact with the driver. I’ve had that problem with the last few C8’s I built with the newer, thinner drivers from Richard. You can test this by wiggling the driver at the spring. If it moves at all, that’s your issue.
Someone in another thread told me to add solder blobs to the outer ring of the driver and that worked. I now take a piece of 18 awg solid copper wire make it circular at the right size and pound it flat.
Thanks for everyone’s help, finally had some time to mess around with my lights. I changed the driver to a h17f and put the other driver in something else and it works great except for my forward switch set up i got. When i jump the body to negative of battery it works perfect so i know its in the switch. It flickers, doesnt come on sometime and when it does work, momentary doesnt work untill the very end of the push. I have a custom washer i ground out and a forward switch i ordered off mountain. Can anyone suggest a better forward switch set up? Thanks!
