5.6 CAN Diode pinout

[steve-o]

Hi All,
Gotta Q:
Are the 5.6 CAN style diode housings standardized or does the pin-out vary from mfg to mfg?
Also, any tips on heatsinking them?
Thanks,
Steve

[mixedgas]

sometimes the PD polarity is flipped and what lead the can is tied to changes, beware of grounding the diode can by accident.
Steve

[The_Doctor]

It's a total lottery, at times. Always rely on the data sheet if you can get one.

Most low power types are positive to can, and the photodiode can be either way round as Steve says. The pin numbering schemes aren't even consistent. There is no substitute for clear diagrams, both schematic symbol, AND mechanical drawing, if you want to be sure.

With DVD types it's far more standardised, because firms didn't want to have to rework a complex design if they were forced to change a diode type. The numbering scheme can still be stupidly variable, but looking from the back, pins oriented like an inverted V, you'll nearly always have postive input on the left, negative to can in the centre, and no connection on the right, because there is no photodiode in the powerful diodes.

There will always be exceptions to the rule, because no-one ever made a rule. One moment makers are fighting to make buyers depend on them, so they make as exclusive and alien a layout as they can think of, the next, they're fighting to avoid losing business, so they adopt someone else's standards to try to get business from their customers.

The easiest way to find out is to track the DVD makers. See who makes what, who's making the drives everyone else puts their little logos and badges on. The net is full of info about this. Track that accurately, and you'll also track what diode standards are dominant, and probably find out what exceptions arise. You might not find who made the diode, but you will find out how it's wired.

And if you buy diodes on eBay and the seller won't give you fully declared data to the best of their ability, ALL bets are off!

[steve-o]

Thanks. I wonder if I could put a dmm on the diode scale across the pins without killing it? Maybe I'll just try to find a datasheet instead and be safe.

[p1t8ull]

There's a good snippit on Sams FAQ that goes over how to determine the pinout of an unknown diode:
http://www.repairfaq.org/sam/laserdio.htm#diodct2

[marconi]

I wouldnt use a DMM, you never know what they use for bias..
Flukes are a good bet but beware.....
Altho, I have done it many times ...there where the few times I actually killed the diode that way, expensive ones at that.
Now, I always use a test driver board and watch the voltage and current and at the same time while hoping for threshold.
Ive had very good luck this way...
of course your milage may vary

[The_Doctor]

Ok, I was going to post and quit thinking it wouldn't be helpful cos it was on shaky ground, but the thread just went the same way I was going to, so...

I tested a couple of Flukes just now, series II, a 77 and 79. Basically, DON'T use the diode test, obvious choice though it might seem. It puts out 2.5V or more (and on the extra, 40 ohm range on the 79), enough to kill a diode if reverse biased in some cases. Maybe safe if you limit the current, but I don't know, never tried.

The low resistance ranges use 1.2V, enough to locate and determine polarity of a photodiode. That's why I didn't post earlier. It won't cut to the chase and find the LD polarity, but it is safe, and it will find the PD polarity and connections, which might sometimes be helpful.

Most resistance test ranges on other meters might be safe, but read the probes with a voltmeter first to look for more than 2V.

[marconi]

"Dont use the diode test"
Thank you... I forgot that one important fact

[steve-o]

The Flukes are at work.. I have a few days off (from work- so I wont be going there ) and all I have here is a radioshack 'micronta') so I'll just sit back and stare at it until I can find some concrrete proof (a spec sheet from mitshubishi) I'm getting tired now so signing off--- even tho it shows I'm still on-line--I just dont log out--thanks Doc--later
S

[steve-o]

Oh I see you chimed in Chuck-- Yeah I thought as much-- I'll hold off on the speculations..