Nov-Mu Teardown: Fireflies’ new driver and modding

I finally have a powerful enough soldering iron to open up larger lights and boy did the NOV-MU require a lot of heat.

I want to have an option to enable the switch LEDs without charging because I’ve sometimes had difficulty finding the switch in the dark. I’m documenting this process because I’ve found Tom E’s tear down and modding photos really helpful when opening and modding lights on my own, particularly the first few times I modded a light. Thanks Tom E!

I used a big C4 T12 tip cranked up to 400C and just dumped heat into the head of this light to desolder the mcpcb wires. This light has an exceptionally good heat path from the mcpcb to the head and I had to wear gloves because of how hot the head got. My EC03 with a bigger mcpcb doesn’t take nearly as much heat.

There was a lot of thermal paste under the mcpcb and shelf is more than a centimeter thick, about 1.1-1.2cm.

I’m not quite sure what material the mcpcb is made out of. The bottom has a colour like that of brass, but very dull like you’ve turned the saturation in a photo down. The sides are a grey shiny metal which makes me think aluminum. The mcpcb is also very lightweight compared to other mcpcb I’ve held. This isn’t a DTP mcpcb because the E21As don’t have a thermal pad, but from how much heat I had to dump into the head, and how hot the head got, I’d say the thermal path is excellent.

Here’s a look at both sides of the driver. This is Fireflies’ new 6A buck driver designed by Loneoceans which fireflies is presumably using in all their new lights. Some lower powered lights like the T1R will probably have the fet disabled.

It includes the two resistors to enable C-C charging.

Here are the components I’ve identified

It uses two identical p-mosfets, one for Reverse polarity protection and one to do switching things.

TPS62480 Synchronous Buck


BQ25616 charging IC

I left off tonight with analyzing the switch LED leads and how they connect into the charging IC.

One thing to note is that the switch LEDs share a common anode (+) instead of the usual common cathode/ground (-) of aux LEDs.

This complicates things since both LEDs connect to VCC of the USB charging, and I can’t just connect an attiny1634 pin to the VCC of the charging IC because that would result in…

since the battery would then be charging itself (I think).

So I believe my best option is to connect the common anode to an attiny pin, the blue switch LED’s (-) to ground, and keep the red LED’s negative connected where it is right now, as an indicator for the charging.

This would result in a blue switch LED which I’d have to figure out how the programming for, and a red charging indicator LED that can only be turned on when the blue LED is also on. There might be a problem with this arrangement but I don’t have the electronics knowledge to figure out why this shouldn’t work.

A more pressing issue is the fact that the Attiny 1634 is on the opposite side of the driver and I can’t just connect a pin over from the spring side to the top side of the driver. Loneoceans did write that there were several jumper pads unused in his github code but I haven’t investigated where those jumpers are or if they even exist.

It’s a bit tricky because I think this is a pcb with more than 2 layers since some drilled holes just exist with seemingly no connection on one side.

Anyhow, that’s an adventure for tomorrow and I just wanted to get this out here since I don’t think we’ve seen any pictures of fireflies’ new driver.

If it ain’t broke, don’t fix it :laughing:

Thanks for the teardown.

I think that would work, but can you not disassemble the switch to rewire the LEDs ?

Indeed, but if Loneoceans designed the board you could maybe ask him if there is an area only with GND pour on the 4 layers where it would be safe to drill.

Aside from that I’d be interested to know how deep the driver cavity is.

Thanks for this. I don’t have this flashlight brand or model, but your insights are valuable nonetheless. Pictures are high quality. Thanks.

I reassembled the light without making any changes. The switch is press fit in and I’ve never really learned or acquired the equipment to remove press fittings and to press them back in so that’s a dead end for me.

I don’t want to drill a hole in the pcb to pass wires through since reliability would be a real concern imo. Loneoceans did mention jumpers 1-4 but I didn’t see any potential locations for where they might be.

Alright.

Was the driver retention ring difficult to unscrew ? i haven’t been able to move it on my E12R.

The ring was glued in. You need to break the glue with some force using your pliers. I didn’t pay attention to the driver cavity depth but looking at my photos, it doesn’t seem very high.

Ah that’s what I feard, I’ll put some heat to soften the glue. Thanks for the info.

Happy to help! The glue wasn’t really tough on both my lights and just a bit more force with pliers was sufficient with my lights.

At least we know why Fireflies has shortage now, that TPS is backordered hard. *Attiny too

Thanks for the teardown! Good to know these new FF lights have exceptionally good heat path from the mcpcb to the head!

You are a brave person Sunnysunsun to take this flashlight apart! The E21As look amazing and everything looks very clean and meticulous.

Too bad about the lighted switch though - that would’ve been nice.

Hi guys, i have a question.
NO charging battery after i mod the E07X.
I never try to charge a battery before the mod so i don’t know if the flashlight usbc port was functional before the mod but now not work.
I use an usb meter between torch and charger but the meter does only a blink (and immediately black screen) and not charge the light.
It is a wire problem or chip problem? Can you help me to find a solution? Anyone can help me?
Thank you

Hi!

I need to disassemble my Nov-Mu after a bad resoldering job. I had replaced the emitter pcb. During the process I mangled up the wires pretty badly. I want to solder new wires, is it possible to pull the driver out of the host far enough for me to resolder the wires? Since I don’t have any methods of removing the switch.

From your pictures it looks like that’s possible.

Thanks