Damaged Sunwayman M25C Ti driver

Flashlight Modding and DIY Parts
1

Dear fellow modders, I once again seek your help.

I have a damaged Sunwayman M25C Ti driver. The output wires got sorted by mistake while I was modding it and now the torch is always on at maximum level and will not respond to the control ring. The way this happened, for anyone interested is that I replaced the MCPCB with a 3535 one and the reflector sorted the wire contact points when the bezel was screwed on. The unlucky thing is that I had covered the contact points with kapton tape, but the tape that covered the positive wire slipped off!

I have emaild sunwayfoto (former Sunwayman) in hopes they may have a driver but I doubt it after so many years. So, does anyone:

  • know if any other torches by sunwayman or other manufacturers share the same or a compatible driver
  • know what component gets damaged on the driver when this happens and can point me to it so I can replace it and possibly repair the driver
  • have an extra driver or two to sell me
  • have an idea that could help

Many thanks

2

Pictures of the driver ?

Edit : it’s a buck driver, it’s posible the high side FET failed from overcurrent and is now shorted.

3

I hope these help.

Actually, I have 2 drivers. I do not know what happened to the first one, probably sorted too, but it is on full when it should be off, then on full when it should be low, then off when it should be mid, then low when it should be high. I replaced the HAL sensors on that one and nothing changed. I got the 2nd driver (2nd torch actually) to replace it and the kapton tape came off and sorted it… Great luck. The 2nd driver is the one I describe above, which is always on full.

Edit: I guess I should remove the coil to offer you a better view?

4

Ok, a bit difficult to see, but the high side FET would be between + and one pin of the inductor. Though it’s possible there is a PFET for reverse polarity protection between it and , Q9 looks like it could be a RPP FET (not sure), it looks connected to and then to a lot of vias to the other side, those via would be connected to the high side FET, this FET could be discrete or integrated in the buck IC which would could be the thing under the inductor.
To see if it’s shorted you would test continuity across it.

Edit : yeah not sure Q9 is a RPP PFET since + is connected to is gate, and the via appears to be gnd.

5

Thank you very much for your help!

I am handy with a soldering iron but not very knowledgeable in electronics. If you are willing to guide me, I will try to get this driver repaired.

First of all, which of the 2 drivers do you think I should be working on? The 1st one that changes output but not correctly or the one that is always on? I think the 2nd is more likely to be an easier fix, but I do not know for sure.

The next step I propose, after you tell me which driver to work on is to remove the coil and send you a better photo of the driver. Then you can tell me exactly what to measure for continuity.

I will need to go out now but I will remove the FET and take the photo later, as soon as you let me know which driver to work on.

Many thanks, I am grateful for your help.

6

Or maybe just bend it.

7

Something like this, try to identify the connections and test continuity across the HS FET or controller depending on case 1 or 2.

The diode (D1 ?) is the big rectangle next to the inductor .

8

Thank you, but I would not really know how to spot all that. Does this help?

9

So the HS FET is Q8 (AO4409), you can see the power traces connected to it. The bottom pins are likely connected to the + button with vias under the FET, and the top pins are connected to the inductor. Test continuity between the two to check if it is shorted.

10

There is continuity between the bottom right one and all the 4 top ones. This is the driver that changes modes but not properly.

There is no continuity the other three bottom ones with any of the top ones.

11

Probably another issue with this one.
I was talking about the always on one.

12

On the always on one, it is exactly like you predicted. The bottome 3 leftmost ones are sorted with all the top ones.

Do you think that replacing the HS FET will fix the driver?

Also, any idea if anything could be done with the 1st driver?

Many thanks!

13

Cool, that’s a reasonably easy fix. You’re in UK so Farnell is good ?

https://uk.farnell.com/vishay/si4463cdy-t1-ge3/mosfet-p-ch-w-d-20v-18-6a-so8/dp/2056686

That’s a better replacement, the original one has fairly high resistance with single cell voltages.

For the one with strange modes I don’t know, though it’s strange that there is continuity between drain and gate.

14

I think it is clear what happened to the 2nd one:

Do you think there is a good chance that the HS FET is the only thing that got damaged and the driver will work if I replace it?

As for the second one, no visible damage and strange behaviour. This one is a mystery…

It would be great if I could salvage that one too…

15

The 1st one has a strange behaviour. When it is supposed to be off, it is on full etc.

Many thanks for the suggestion for the chip. I will order it and hope it will fix the driver.

EDIT: Farnel seems to have introduced a small order handling charge of GBP 9.95! It is very hard to get small quantities of electronics in the UK right now, without paying some ridiculous surcharge or another. I will get it of course, if there is no alternative, but I usually look on AliExpress, believe or not, because even though they ship from China, they turn out to be much cheaper. Any suggestions from them? I am not being lazy, I just would not know what to look for, such as the lower resistance you mentioned.

16

Is it possible that the driver is assembled in the wrong orientation or that the magnet in the selector ring sits at the wrong position? You could check the driver without the host, just a power source and LED/load (make sure that it doesn’t burn out in high modes), using a small magnet that you move around the sensors.

17

SammysHP, thanks for the suggestion. I am afraid that is not possible. It was a similar mistake that I did not notice the first time round that caused the issue with the 1st driver too. It was initially working properly.

18

Yeah there are fees under 30€ with Farnell France too, usually I have other stuff to order to get no fees and free shipping.
Radiospare has a non business website with free shipping during the weekend in France, I don’t know if it’s the same in UK.

Searching on aliexpress is kind of a pain, well there is the AO4409 on there so that’ll work.

The mosfet parameters would be to be

- P-channel

- SOIC/SOP 8 package

- VDS> 10V (for 2S cell)

- VGS> 10V (for 2S cell)

- total gate charge at VGS=‐4.5V similar or lower than AO4409 (around 50nC)

  • RdsON similar or better, preferably with a VGS = –2.5V rating, as you can see in figure 5 of the AO4409 datasheet, the resistance increases a lot below Vgs = –4V
19

Thank you. I will have a look but I want to get something of high quality so I may end up ordering what you suggested and eating the fee...

Your help has been invaluable and is really appreciated.

Do you think that replacing the HS FET on the 1st driver is worth it? Is there a chance that it failed, albeit less spectacularly? It seems more like a logic or sense issue to me rather than a FET issue, that is why I already replaced the HAL sensors on it but the result is the same.

20

After a long search, I came to this conclusion: I can get the chip from AliExpress, but it would be of questionable specs and quality or I can swallow the ridiculous handling fee and get it from Farnell. thefreeman, thank you very much for your help with this. It was very kind of you to share your knowledge. Since I am ordering from Farnell, do you have any suggestion of anything else I could get to try and fix the other driver? Maybe I could read the firmware off the logic chip on the 2nd driver (assuming the only damage on the 2nd driver is the HS FET) and program a new logic chip to replace the one in the 1st driver? I probably have no idea what I am talking about. I would just prefer to get all that I may need to try on one order so I do not have to pay the handling fee multiple times.