The BLF GT70 "Giggle Monster" is here! 7,500lumens, 1,500m throw! Group buy Closed!

Update on the conversation with lumintop. After a while of back and forth emails with them they are going to send me a new driver. For $20… Just waiting by the mail box now. As I’ll now have a spare driver that only requires a FET replacement, can anyone point me to what FET I should be looking for? I figure there’s no loss if I kill it now so I may as well try fixing it.

I can’t remember what the driver looks like, but with most of TA’s FET drivers he uses this style FET.
http://www.mtnelectronics.com/index.php?route=product/product&path=25_76&product_id=565

There’s a few really good MOSFET models out there like the Infineon BSC009NE2LS5IATMA1, for instance. I’m not sure what’s available near you, though. The genuine ones can’t usually be bought from China. Hopefully some Australians can point you in the right direction where to buy some good ones. They are cheap so you can buy several as extras.

Yeah, there are a lot of FET’s out there that will work just fine. The Sir800 / Sir404 are good options. the BSC009NE2LS5IATMA1 is better but harder to find.

In a pinch these should work as well:

PSMN1R7-25YLDX
PSMN1R5-30YLC

Thanks so much for the info lads. I’m really grateful you are here and helping a newb such as myself. Hopefully my next update has the GT all repaired.

So Lumintop are being quite slow with the replacement driver. I’m not sure when it will be here. I did however receive the new fets in the mail along with some solder paste, and some braid for solder removal. I watched some youtube, did some reading, and practiced for a while on an old video card removing and replacing small surface mount components. I found it was basically impossible for me to move anything larger than about 2mm without hot air. And my hot air gun is better suited to melting poly pipes for plumbing than microscopic circuit board components.

Nevertheless I thought it would be worth a go, and I thought I had a reasonable chance of success. It was time to have a go at the GT itself. Quite a daunting task for a total noob such as me. I was as precise and careful as my fat fingers would allow and in the end it looked kind of ok… put it all back together and…… same exact issue. The light fires up fine, and on ramp it just reaches the same dim level it did before the fet swap.

Anyone have any other ideas? Did I roast the fet, or install it wrong? Can I check it with a multimeter? Sorry to be a pest I’m just at a loss of what else to do.

before:

after:
!https://drive.google.com/file/d/0ByQSXXcbJReWdUR1Zm5sU0NIR0lGdHcxZ01CdnNxN3N1WFZz/view?usp=sharing https://drive.google.com/file/d/0ByQSXXcbJReWSW1YM2FuN1dFSjJFOEVQekw1NkMtVUI3aS1J/view?usp=sharing https://drive.google.com/file/d/0ByQSXXcbJReWS043S0RLZk1fTE0zWFZ5c2xBRTZZN2N6NGxN/view?usp=sharing!
ready to turn on again …
https://drive.google.com/open?id=0ByQSXXcbJReWYUNYT2J1eVQ2RWw3Q2d5LVYxLVpvOUdnRHNz

It doesn’t look too bad. I usually take my iron and go along the sides if the FET to remove any excess solder. It looks like all 4 of the small feet got soldered.

I’m not sure why that didn’t fix it. I use leaded solder for its lower temps and only get the components hot enough to melt the solder. No extra heat is desirable.

Maybe the driver is not putting out a proper signal to the FET. It’s the FETs that are most sensitive, though so they tend to be the first thing that goes bad.

In the last picture it looks like there is a broken trace where the MCU mounts, that particular pin doesn’t go to the FET IIRC but if one pin is bad it is not a strech to think another might be. It could very well be something in the path to the FET that is the issue.

If you have a bench power supply there are some tests you could run but without it you would need some way of providing power to the driver while it is out of the light.

hmmm. I don’t have a bench power supply. I guess this repair was a bit too much for me :frowning: back to waiting by the mailbox.

Is there something wrong on this component or is this an artifact of the photo or a piece of black thread?

Yes, that is what I was referring to. That particular pin should not cause the issues he is having IIRC but if one pin has an issue it is possible others do as well.

@lawallac:

I cannot see your photo.

Ok tried to relink it with sharing.

Now I see it.

I think I’m going crazy.

The replacement driver (finally) arrived today and I was very keen to swap it in. All the hard work of pulling the light apart was already done so it was a very quick job, just a couple of wires and it was ready to go.

To my dismay it behaved exactly as it did beforehand. Blinks on when batteries are in as expected, then in ramp mode it just stops at about 10% power and then blinks again about 3 seconds in to the ramp. Double click only reaches the same low power mode.

When it was suggested that I could replace the FET and it would fix it, I ordered a few FET’s and a spare xhp70 12v emitter as well. So having a spare XHP70 I thought perhaps it’s just the emitter. I popped in the new emitter and …. full blast activated! for about 1/2 a second. then it was back to low power.

Again , it would ramp to about 10% and never get brighter. Something different about the mtnelectronics xhp70 was that it only lights 2 of the 4 sections of the die in moon mode, then 3 , then all 4 as it gets a little brighter. quite odd.

Have I just got a magic touch and am destroying these parts as I touch them? Could it be my batteries? Does the driver sense any weakness in the batteries and refuse to go full power? Please guys- any suggestion is welcome at this stage I’m at my wits end.

Again, sorry for being such a newbie.

It’s kind of normal if moon mode only lights a few dies. As long as all 4 come on just above Moon mode. The driver provides a really tiny amount of power at it’s lowest so the dies just barely light up.

Are you using 4 or 8 batteries?

What voltage does it blink out after 3 fast clicks?

Make sure the battery tube is fully tight to the head first, then tighten the tail.

Man, I don’t know what to think.

You didn’t accidentally get the drivers mixed up and put the old one back in, did you?

Is the aluminum shelf the driver sits on nice and clean?

All screws in the battery carrier tight?

One more thing, your using unprotected batteries, right?

When I first had problems I checked the voltage of each cell, checked the voltage of each carrier, with a multimeter and with the voyage test mode of the light. Over 16 volts from memory. No cell was out by any notable amount.

I have since got the short tube and tried to use 4 cells. Same problem.

I’m sure I didn’t mix up the drivers. The whole thing is spotless, brand new. Connections are clean as.

I’m starting to lean towards the batteries being the problem. They are unprotected, they were flat tops and I soldered a blob on the top of each of them to make them button tops. I guess they are the problem…. what else could it be?

One of the solder blobs may be just tall enough to touch, but not touch strongly. Maybe the jolt of high amperage causes the connection to break.

I’ve seen this happen on high powered lights where the tail cap or head wasn’t getting a good connection to the battery tube or the battery ends or spring ends were dirty.

I don’t suppose your charger shows internal resistance? I’d wondering if maybe the batteries got damaged when you were doing your solder blobs. You do have to be pretty quick and deliberate because it can quickly damage the cells. It certainly wouldn’t hurt having 4 or 8 good ones as backup. What cells are you running anyway? Thanks.

Using some “Panasonic-Sanyo
NCR18650GA 3500mAh” …. care of eBay …

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com.au%2Fulk%2Fitm%2F152713100141

Being that I’m having issues I’m starting to question there legitimacy…

That ad looks correct.

Did you check that your solder blobs are sized so that it has the right width and height? You might have to shine a light in there to check the gaps.

You want to see a tiny air gap all around the shoulder of the battery and on the sides of the solder blob. That way you know the spring is pushing the solder blob into the terminal with force.