Driver not putting out full power

[irishluck]

If you hook the X-Drive up to your test load NOW, and measure the current, is it still supplying 200mA?

Yes. It is still supplying 200mA.

But before when I connected up the diodes, it was very bright, now my diodes are very dim.

 

[The Lightning Stalker]

There are many different types of 12V wall power supply. Can you describe it in more detail? Pictures
would be most helpful, especially clear readable ones of the label.

 

[Benm]

I know this because the first couple I tried were very bright and the voltage drop was from 12v to about 7v.

The last couple ive tried are very dim and the drop is from 12v to about 2v.

So I know these are suppose to be alot brighter.

7 volts across a ML101U29 would be extremely unlikely. At operating current (say 200 mA, but also pushing it towards 300 or so) the voltage over the diode should not be over 2.5 volts or so - certainly NOT something like 7 volts.

Also, 7 volts is so much too much i'm not inclined to believe your measurements were correct with functional red diodes as the load. Perhaps you measured at the wrong point, or your meter was thrown off by the high frequency output of the driver.

I'm not sure how well the x-drive would tolerate being operated at open circuit, but it is possible you have damanged it by running it without a load. Linear drivers usually don't have any problem with that, but switching drivers can be damaged by operating them unloaded if no provision is taken in their design for that condition.

 

[rhd]

I'm not sure how well the x-drive would tolerate being operated at open circuit, but it is possible you have damanged it by running it without a load. Linear drivers usually don't have any problem with that, but switching drivers can be damaged by operating them unloaded if no provision is taken in their design for that condition.

I don't think he damaged the X-Drive, I think he damaged all of his diodes.

I keep coming back to this statement:

12v going into the driver, and 12v coming out of the driver when no diode connected.

I'm not entirely clear on where this phrase is coming from, but I get the strong sense that in some way, shape, or form, the driver was given power, without a load connected. There is no other way in which this statement would make sense. With "no diode connected", if he had a test load connected, the output would not measure 12V. Basically, the only way I can think of to get a measurement of "12v coming out of the driver" is if you just hook up DMM leads to the output, and turn it on.

I think the OP did exactly that, and ended up charging up the output capacitor on the driver in the process. Then, he connected up his diodes, and discharged the caps into each one, causing them to go LED.

That's my theory based on the fact that his driver still works and outputs the correct current when he tests it on a test load.

He killed his diodes. That's my theory. Happens to everyone at some point.

 

[irishluck]

I don't think he damaged the X-Drive, I think he damaged all of his diodes.

I keep coming back to this statement:



I'm not entirely clear on where this phrase is coming from, but I get the strong sense that in some way, shape, or form, the driver was given power, without a load connected. There is no other way in which this statement would make sense. With "no diode connected", if he had a test load connected, the output would not measure 12V. Basically, the only way I can think of to get a measurement of "12v coming out of the driver" is if you just hook up DMM leads to the output, and turn it on.

I think the OP did exactly that, and ended up charging up the output capacitor on the driver in the process. Then, he connected up his diodes, and discharged the caps into each one, causing them to go LED.

That's my theory based on the fact that his driver still works and outputs the correct current when he tests it on a test load.

He killed his diodes. That's my theory. Happens to everyone at some point.

The cap cant be charged because before I connect up a new diode, I touch a bleeder resistor to the driver to discharge it for safe measures.

BUT you could be right that I attached my meter to the driver and turned it on. I cant recall if I did but im not saying I didnt either.

 

[rhd]

The cap cant be charged because before I connect up a new diode, I touch a bleeder resistor to the driver to discharge it for safe measures.

BUT you could be right that I attached my meter to the driver and turned it on. I cant recall if I did but im not saying I didnt either.

Regardless, the bottom line is that your driver still works when you test it by connecting to a test load.

If the driver still works, there's only one other piece of the puzzle - the diodes.

 

[irishluck]

That just dont make sence. Why would they be bright then all of a suden all be dim?

 

[rhd]

That just dont make sence. Why would they be bright then all of a suden all be dim?

This is why \/

I don't think he damaged the X-Drive, I think he damaged all of his diodes.

It's the only explanation that does make sense. You LED'd your diodes. If the driver is still working, I don't understand where you think another point of failure could be hiding, if not in the diode? It's not the power source either, because if there was a problem supplying enough current, you'd see that deficiency on the test load.

There are a limited number of points of failure, and all can be ruled out by the diodes, no?

....I suppose you could have black sharpie on your lens....

 

[The Lightning Stalker]

Where did you get the diodes?

 

[irishluck]

This is why \/



It's the only explanation that does make sense. You LED'd your diodes. If the driver is still working, I don't understand where you think another point of failure could be hiding, if not in the diode? It's not the power source either, because if there was a problem supplying enough current, you'd see that deficiency on the test load.

There are a limited number of points of failure, and all can be ruled out by the diodes, no?

....I suppose you could have black sharpie on your lens....

well if that's the case, I still have diodes that I haven't tested yet. how do I prevent LEDing them or what ever you call it to the remaining diodes I got.

 

[Benm]

Power them from a current-limited lab supply and slowly ramp up the voltage (make sure to start from zero volts, confirm output voltage is zero with a multimeter when controls are set at zero).

As for what has happened so far: If you measure 7 volts across a red diode you can safely assume that diode is dead (or connected in reverse). It would be a shame if you blew up several diodes, but it IS possible. If the driver still provides properly limited current into a test load, yet your diodes only light up like dim led's this probably is the case.

If it is, stop what you have been doing: it managed to blow out those diodes before, so it will likely blow out any new diode you try in the same setup.

 

[Speedy78]

Are your diodes in any sort of heat sink?

 

[irishluck]

Id like to update this post to find out if I can still find out the issue with my diodes.

I have images this time as well.

I hooked up the test load and had the pin set on the second pin.
My meter measures at .200

I took my meter off the test load, the test load still connected, and measured the voltage before the test load and it measured at 2.41v.

So how do I explain that my first couple of diodes were bright and all the rest are all dim?

 

[The Lightning Stalker]

Before you connect a diode, you have disconnect the power and short the output of the driver to discharge
the capacitor. If you did all that before attaching the diodes, then there is something more going on that
the multimeter doesn't show. I have heard of fans causing spikes on supply rails and killing things. The
driver could also be introducing transients. These things are all too fast for the multimeter to catch.

 

[BShanahan14rulz]

Reds are pretty sensitive, red open cans even more sensitive. My only high power reds were LOC, and of the 5 I had, I killed 2 or 3 of 'em. Now, I had five, so I wasn't as cautious as I could have been, but things you can do to protect your diodes from ESD is you can wrap a strand of wire around the pins, tight enough so that they are electrically connected, but loose enough that you can detach the wire strand after you've soldered the diode to its final place, or when you are about to test it. Idea is that any electrostatic charge across any pins on the diode will be equalized across the wire rather than through the laser chip.

And what Lightning Stalker said. Be sure that you are discharge your caps before adding diode. If there is no load, t he cap will basically charge up to whatever the max voltage the driver can put out with no load. Then, when you attach load, the cap discharges at that voltage, which will be too much for the diode.

 

[irishluck]

Long story short with this one, I had some bad diodes.