KES-400A Breakdown Voltage

[Ryo]

I was wondering how do you determine if a KES-400A Diode is good?
I recently ordered 3 PHR-803A KES-400A sleds from Daedal.  I harvest them from their sleds, and wanted to determine if they are good.  So I decided that the best way is to take my trusty Fluke 189 and measure the diodes.  Here are my results:

		#1	#2	#3
Pin	Desc	BDV	BDV	BDV
1	VLD (Blue/Violet)	3.26V	OL	OL
2	IRLD (IR)	1.45V	1.45V	1.45V
3	PD	0.88V	0.94V	0.86V
4	RLD (red)	1.77V	1.77V	1.77V

Since the Blue/Violet diode portion gave me OL reading on 2 of the diodes but a 3.26V value for #1.  I did noticed all 3 lit up when the diode's breakdown voltage was being measured.

Does that mean 1 or 2 of my Blue/Violet LD is bad, or measuring the BDV not a valid way to check if it's a good diode?

Thanks.

FYI:

 

[Ryo]

Hmm.. guess no one has ever measure the breakdown voltage of a good blu ray diode?

 

[pullbangdead]

I'm confused...are you you measuring a PHR-803T diode that you ordered from Daedal, or are you measuring a KES-400A diode to practice first?

Or are you saying that you were able to successfully measure the voltage of all 3 PHR-803T diodes but now 2 of the KES-400A diodes you have don't work right, and you don't know why?

 

[Ryo]

Maybe I'm confusing myself... but I thought the PHR-803T sleds used the KES-400A diodes.  

All 3 diodes from the PHR-803T/PSXBoy sleds are "new" from Daedal.  I am planning to mount them in to a Aixiz housing, but I wanted to make sure that they work before I did it..  I was using my FLuke multimeter (in diode mode) to measure the breakdown voltage of the laser diode.  The values I measure using my Fluke MM is listed in the table I made.  Any case I am trying to find out why 2 diodes have breakdown voltages different from a third one.  

I haven't powered any of these yet so they can be good or bad. I was hoping someone had measured the breakdown voltage of a known good one..

FYI the Fluke MM in diode mode limits the current to 1mA, not enough to drive the laser, but enough power to actually cause the laser to emit.  THis is why I know my BluRay LD isn't dead for all 3, but didn't know if I got any that became a nice LED.

 

[pullbangdead]

KES-400A is the sled from the PS3.  It has one can with all 3 colors of laser light (IR, red, violet) incorporated in the one can, so it has 5 pins.

PHR-803T is the sled from some HD-DVD players and some other Toshiba drives.  It has 2 cans: 1 is 3 pins, and that one is JUST violet.  The other can has 4 pins, and that one can has both IR and red laser diodes in it.  


Did your PHR-803T sled come with 1 diode can, or 2 diode cans?  Does the diode from it have 5 pins like the layout you pictured?



Edit to add: Really, to check if the laser diode still lases (isn't just an LED), you need to give it current above its threshold current. If it's a PHR-803T diode, just rig up your driver, so some other simple one, and give it some real current - 50mA, 80mA, whatever; you can go 100mA with no real heatsinking for a second or 2 just to see if it lases. I don't remember off the top of my head where threshold is for them, but give it some real current above threshold is the easiest way to check if it's all good.

 

[Ryo]

Thanks for clarifying.. I do have a KES-400A diode since it has all 3 laser diodes (5 pin). I don't know where I got mixed up then.. Shows how much I know about the diode model #. Everyday I'm learning. Well if powering it up for less than a second is the way to do it.. then I guess I have to do what I have to do. Good thing is I have a Fluke Calibrator 5520 which is very accurate. (used in all cal labs)

Would I just power up the diode by clicking the on and off button from the calibrator or would I just touch the lead of the diode with a live voltage coming from the current limited power supply? I would think the latter would be bad.

I'm also assuming I would be using 4.6 volts to power the bluray LD.

BTW when I was talking about LED.. I was talking about a laser being damaged and functioning like a LED..

 

[pullbangdead]

Yep, that's what I meant about the LED as well, that as long as it still lases it's not just an LED, and that's a good thing. We're on the same page there.

Since it's a KES-400A, don't give it more than maybe 40mA. Many give it 38mA since that's an easy value to get with an LM317-based driver (33ohm resistor, if I remember correctly).

About the voltage...well generally, for laser diodes it's better/easier to worry about current control. If you feed it a controlled current, it will take the voltage it needs as long as you supply an excess of voltage. With the drivers in use on here, you supply an excess of voltage and the exact current, the diode takes the voltage it wants, and the excess is taken up in the driver so it doesn't damage the diode. You can theoretically run with a constant-voltage source, especially if you're monitoring the current and ramping up the voltage slowly, but it's generally accepted around here to do it with constant-current control. Remember diode behavior is exponential, small changes in voltage are huge changes in current, so it's much easier to control the current rather than trying to find the right current by adjusting the voltage. If you're ramping up a constant-voltage supply, just be REALLY careful to go really slow.

As far as the power supply to test it, just using the switch is fine I guess, I don't recognize the device you're using in particular. Or, I have soldered all joints but one and then just used that one broken joint as my switch for a quick'n dirty test.

 

[Daedal]

Thanks for clarifying.. I do have a KES-400A diode since it has all 3 laser diodes (5 pin).  I don't know where I got mixed up then..  Shows how much I know about the diode model #.  Everyday I'm learning.  Well if powering it up for less than a second is the way to do it.. then I guess I have to do what I have to do.  Good thing is I have a Fluke Calibrator 5520 which is very accurate. (used in all cal labs)

Would I just power up the diode by clicking the on and off button from the calibrator or would I just touch the lead of the diode with a live voltage coming from the current limited power supply?  I would think the latter would be bad.

I'm also assuming I would be using 4.6 volts to power the bluray LD.

BTW when I was talking about LED.. I was talking about a laser being damaged and functioning like a LED..

I'm sure the 5520A is a great way to calibrate equipment, and I'm also certain (from experience) that it's pretty stable on the output. But I honestly cannot speak much for its ability to power up a laser diode safely. I have no idea how the start-up of the signal takes place on it as I have never tested it myself. With a diode like the ones you have, I would be careful, and I would personally advise using some external capacitors... just in case

Good luck;
DDL

 

[Ryo]

Will do, thanks for the warning.

 

[viroy]

Say, theres used KES-400A lasers on ebay right now for $30 with shipping from the usa.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290258034514#description