Topeak Whitelite 1W LED Cycle torch

[andypandyplod]

Hi,
I am trying to repair a 'Topeak Whitelite 1W LED Cycle torch'which is powered by a 3.7 volt CR123 battery.
I had to replace the Luxeon 1 watt LED.It works correctly at full brightness when connected to a 5v supply to the 3.5mm socket (allows a separate 5 volt battery to be connected).The push button allows Full on,Flashing and off.I found the 3 pin SMD device marked 015PB,(M1 on PCB),was open circuit.I have managed to get the torch to work by replacing it with a BC327 PNP transistor on short leads,because of its size.It appears the brightness is down 50%?.I cannot find any info on the faulty device,and wondered if it was a digital transistor,or a mosefet?I know there is a LD1117 3.3v output,used a constant current device,and a 5104A device used to boost the 3.7 volt battery to 5 volt. I have attached a PCB photo,and a circuit,which may not be completely correct.Any ideas please?

 

[large_ghostman]

I think M1 is something like this **broken link removed**
its probably a mosfet, although I doubt its the one in the data sheet. I had trouble finding the exact part number. I think maybe you have the pins wrong on the pnp, without seeing how you have it wired I cant tell, maybe one the smart people can help

 

[andypandyplod]

Thank you for your reply,I could not find anything with an 015 part number,and you have.The rough sketch I drew could well be wrong,it was just to find out what the device did,I know there are two main circuits.One is producing 5 volts from a 3.7 volt Lion cell. The second is a constant current circuit to drive the 1 watt LED at 350mA . It is only the upc which as usual a black blob with inputs and outputs which is hard to see what it is doing.

 

[large_ghostman]

A couple of decent pics of the front and back of the board might help, it would at least give an idea if you have the transistor back to front