burnt out diode??

How could you tell if the diode has blown?

recently, my leadlight started playing up by suddenly turning off while pressing the button. after a few clicks, it would come back on.

initially, i thought the switch was faulty.

but today, it's had it's last day.

i've taken it apart to test the switch by shorting the two contacts at either end of the switch. it worked momentarily, but then it wouldn't come back on again.

so now that i've eliminated the possibility of a faulty switch, i need to find out where the fault lies. how can you tell if it's the diode, or some other component on the PCB?

many have experienced fluctuations in their beams, but i've never had any history of any fluctuations. i've always had the pot turned to minimum to prevent killing the life of the diode, so i don't think it's due to over powering the diode.

does anyone have any suggestions?
warrenty has been void as i've taken it apart already

thanks

Check the spring length, and any mods you have done for bad solder joints. If it works intermittently, it is probably not the LD.

The switches are pretty much junk, and you were right to suspect it.

good luck

HI Corona,

Thanks for the tip, but i know it's definitely not the switch.
i've connected the positive to the body, and bypassed the switch by connecting the negative to the actual contact on the switch.

upon closer investigation, i did notice quite a few tiny tiny solder balls over the circuit board. the balls must have shorted out the IC or some other component.

looks like i'll have to save up for a new laser, or replace the IC.

i'll try resoldering everything on the board. don't know how i'm gonna resolder the legs on the IC as they are so close.

try resoldering everything but the IC's. Unless, of course, the IC's are also suspects

Checking diodes for failure is easy, diodes block current in one direction and allow it in the other direction.if it permits flow in both directions or blocks flow in both directions scrap it.

Actually, a laser diode can still act as a semiconductor diode (pass current one way) and yet be busted. One common failure mechanism is due to optical degradation, where the laser facets are ablated (cratered) by excessive power density at the exit mirror. It will still emit plenty of IR energy in this condition, so you can't even test it with an IR sensor card or IR-sensitive CCD camera and know for certain.

The only way to know for sure is to operate the diode above the threshold current and measure the IR output power with a laser power meter. If it measures within spec, it is good. If it measures really low, it is toast.

Or you can shoot it through a known good crystal set and look for green