Help identifying Motorola diode.

Do you have a question? Post it now! No Registration Necessary

Translate This Thread From English to

Threaded View
Hi all,
I'm trying to identify a Motorola surface mount diode.

The code on the didoe is 607 with a datecode of 9318. It's a Motorola from  
the logo. I've not had success with google trying to find it, would anyone  
have any ides? I think it's azener, or perhaps a schottky.

Thanks
Greg
(sorry if this posts a second time, tpg doesn't seem to post out)  



Re: Help identifying Motorola diode.
Quoted text here. Click to load it

I can find a Motorola reference referring to their 1N607 and 1N607a diodes,  
which the reference states can be replaced with a 1N4001 - far from a Zener!  
Whether the "607" on your device refers to 1N607 or something entirely  
different though, is anyone's guess.

The reference sheet's here; click the thumbnail to download the PDF -
http://www.datasheetarchive.com/dataframe.php?file=DSA8580006665.pdf&dir=Datasheets-X1&part=1N607

You might want to contact WES in Ashfield (Sydney) and ask for their  
thoughts; though I haven't dealt with them in several years, I remember  
their staff being very knowledgable.

--  
Bob Milutinovic
Cognicom


Re: Help identifying Motorola diode.

Quoted text here. Click to load it
Hi,
no it's not a 1N400x type didoe, it wouldn't have broken down at around 15v.  
See my reply to Phil, I expect it's a 15v Zener. Also, looks like the 1N607  
is a DO-4 case style, not an SMA or SMC surface mount type case.

Thanks
Greg  



Re: Help identifying Motorola diode.

"gcd"

Quoted text here. Click to load it

 ** Why not test it  -  if it still functioning.



...   Phil




Re: Help identifying Motorola diode.

Quoted text here. Click to load it

Hi,
 I'm reasonably sure it's damaged.

I didn't reverse engineer enough of the circuit  and found this diode  
directly across a filter cap after a 2 diode rectifier in a smps after it  
heated enough to melt the solder on the board. (wound the external supply  
up to 15V with 100-150mA current limit set).

 So the diode now measures around 0.7V forward and breaks down at around  
17-18v.

In the circuit it's directly across the  filter cap with no current limit  
resistor so I've either damaged a  15v zener or I've damaged a 15v schottky  
that was there for some unknon reason.

I've checked all the smd code websites and pdf that I can find but no  
reference to a motorola diode with code 607.

I'd suspect a 15V zener but I'm loathed to put one in there with no  
resistor. The smps circuit maintains it's fault without the diode, so I can  
still do some fault finding.

Greg  



Re: Help identifying Motorola diode.


. . .

Quoted text here. Click to load it

Transient suppressor maybe?

Did you try searching for Onsemi instead of Motorola?


Andy Wood
snipped-for-privacy@trap.ozemail.com.au

Re: Help identifying Motorola diode.

"gcd"
Quoted text here. Click to load it

** SMPS often have sacrificial zeners across DC outputs.

When the PSU goes haywire and the DC voltage rises out of control, it fails  
short and prevents harm to the attached load.

A crude crow-bar circuit, in fact.


...   Phil  



Re: Help identifying Motorola diode.

Quoted text here. Click to load it

zener it is then, wasn't aware that such techniques would be used,  
particularily as this smps is form a rather expensive hf receiver.

thanks
Greg  



Re: Help identifying Motorola diode.


Quoted text here. Click to load it

Phil is probably right with "crude crow-bar" - the not so cheap & nasty  
version uses a zener (taking Vgate into account) to latch a SCR across the  
rail, a fuse is pretty much essential.  


Re: Help identifying Motorola diode.


Quoted text here. Click to load it

Sounds like maybe a zener, while regular diodes can drop as much as 1.1V at  
max rated current, 0.7V is regarded as "nominal". In actual fact; a DMM  
diode check is likely to show nearer 0.65V (even lower for fast diodes) -  
the diode check will actually show 0.7V on a zener.

Shottky-barrier diodes vary considerably depending on current rating, I've  
measured as low as 0.1V for big stud mounted rectifiers, and (I think) about  
0.4V for the likes of a 1N5817 etc.

The low reverse breakdown adds credibility to the idea of it being a zener.  


Re: Help identifying Motorola diode.

Quoted text here. Click to load it
Hi,
the 15V breakdown also made me consider the schottky, that's a typical  
schottky breakdown voltage.
But a zener sounds more logical than a schottky. However such a brute force  
approach is likley to cause collateral daamge within the smps than something  
more elegant.

Cheers
Greg  



Re: Help identifying Motorola diode.

"gcd"

Quoted text here. Click to load it

** Like hell it is.

Quoted text here. Click to load it


** Wired in parallel with an electro -  of course it's a zener.



...  Phil





Re: Help identifying Motorola diode.


Quoted text here. Click to load it

Hopefully your SMPS has an overcurrent trip.

BTW: you're unlikey to find many SB diodes less than 20V, except in VHF/UHF  
small signal applications.

They do however get used as sacrificial crowbars - I've found them  
occasionally protecting the G-S of the SMPS MOSFET in PC monitors - more  
often than not regulation failure caused core saturation and blew the  
internal structure of the MOSFET and/or the source current sense resistor,  
if the clamp diode protected anything at all - it was usually the SMPSU  
chip.  


Site Timeline