Driver running extremely hot

[REVENGE]

I'm noticing that my rckstr driver is extremely (painfully) hot to the touch, even though I'm only reading ~23mA of current load with a PHR attached.  Is this something to be expected?

 

[daguin]

Something is shorting out somewhere.

Peace,
dave

 

[REVENGE]

Something is shorting out somewhere.

Peace,
dave

With the diode soldered on, is there anyway I can tell if those two joints are shorted out? I'm inspecting it visually, and I see nothing suspect.

 

[REVENGE]

Also, I ran a continuity test, and got that the joints joining the positive and negative pins of the diode to the driver pads are continuous. Is this normal?

 

[rkcstr]

Well, first, how are you measuring 23mA of load?  What are you connecting where to measure the current?

Next, when you say the pads are "continuous", is that with the laser diode attached?  Also, have you tried resistance?  That will tell you if there is a short, if it is 0 ohms or very low resistance (ie less than 1-2ohms, depending on your meter's resolution).

 

[REVENGE]

For load, I'm measuring with my multimeter leads connected to the positive/negative solder joints on the pads, with the PHR soldered on.  Yes, the continuity test is with the diodes attached, and once again with the leads on the positive and negative pad joints.

 

[rkcstr]

Depending on your multimeter's load for measuring current, you may (and probably will) not be getting an accurate reading. Your meter must get the full current going through it, which means it has to be in series with any other load, or be the only load connected to the driver. When you are measuring across the pads with the diode connected, that's a PARALLEL load. To be in series, you'll need the positive terminal of one load connected to the negative of the other, with the other leads acting as the positive and negative connections to the driver (if that's confusing, google it). Or simply just connect the multimeter wires alone to the driver (use wires soldered on to connect it).

It would be better to test for shorts by measuring ohm's rather than continuity. Continuity just means it is passing current, but it may still be passing current through the diode rather than a short. If you simply measure ohm's you'll know if it's a short or not.

 

[Mohrenberg]

i once had the pos. wire cross onto the mosfet "thingy"......it make the laser beam flicker a little....so i open up the laser, and pressed the module up to my mouth (seems my lips are a good judge of heat)

and i burned the crap out of my lip......it actually charred the pcb board...stuck up my hour and my hands......but the driver still worked and my diode even lived (after cutting away some of the board and bridging over the mosfet) ;D

 

[REVENGE]

Depending on your multimeter's load for measuring current, you may (and probably will) not be getting an accurate reading.  Your meter must get the full current going through it, which means it has to be in series with any other load, or be the only load connected to the driver.  When you are measuring across the pads with the diode connected, that's a PARALLEL load.  To be in series, you'll need the positive terminal of one load connected to the negative of the other, with the other leads acting as the positive and negative connections to the driver (if that's confusing, google it).  Or simply just connect the multimeter wires alone to the driver (use wires soldered on to connect it).

It would be better to test for shorts by measuring ohm's rather than continuity.  Continuity just means it is passing current, but it may still be passing current through the diode rather than a short.  If you simply measure ohm's you'll know if it's a short or not.

No, that is not confusing at all, I was totally being a dumb*ss and the fact that I was happily measuring a parallel load without it crossing my mind for some reason is a little disturbing. XD

Thanks, I'll go and do some proper testing later.

 

[REVENGE]

i once had the pos. wire cross onto the mosfet "thingy"......it make the laser beam flicker a little....so i open up the laser, and pressed the module up to my mouth (seems my lips are a good judge of heat)

and i burned the crap out of my lip......it actually charred the pcb board...stuck up my hour and my hands......but the driver still worked and my diode even lived  (after cutting away some of the board and bridging over the mosfet) ;D

I can only wish that either my diode or my driver survives after this.

 

[rkcstr]

Well, the drivers are pretty tough to destroy unless you physically damage them.  The diodes aren't quite as durable, though.  Hopefully you weren't overdriving the diode beyond its capability.  If not, it's probably just fine.

And, my driver does get hot (possibly VERY hot, upwards of 120C) during use.  This doesn't really hurt the driver, but it may hurt you!  So, be careful!  And, don't forget to heatsink that diode  

 

[Mohrenberg]

heh it was just the pos. wire crossed onto the pin on the mosfet that leads to the - wire, and it harred the pcb black and completely destroyed the mosfet.......

i desoldered it, wiped it with a q-tip and then bridge the pads where the mosfet is suppose to be and it works fine.......i still have it actually.....since i can't sell it now.

 

[rkcstr]

If you do that, make sure you don't accidentally short the ground pin for the MOSFET too, otherwise you'll probably end up popping that small trace since it will short the battery.

Otherwise, the MOSFET isn't necessary... just don't reverse the polarity or you'll probably damage the driver and cause it to put out an unpredictable amount of current (probably around 300-900mA).