SMD code PJ88 Diode SMB8 package

[nevetslab]

I have an IT product on the bench at the moment, helping our IT man that keeps the complex running. A daughter board in this unit (made by Edgewater Networks, Inc. Model 800PoE....a CAT 5 switch of some sort) is full of SMB8 packaged diodes (of type yet unknown). Case Size is 5.2mm x 3.6mm.....believe the package is an SMB8. The SMD Code on it is PJ88. I found the culprit that shut it down, now trying to identify it.

I've only been able to find PJ as a code, which is a SOD123 package, translates to a DDZ20C....20V zener. That's definitely NOT the part in question.

Does anyone have a SMD Code Book that can cross this PJ88 SMD part to it's true identity?

Many thanks,

Steven

[Jazz P Bass]

I don't know if this will help or not.

Transient voltage supressor.

SMB Components.pdf

[mozwell]

I hate SMD codes....
Translated from Romanian
"Diode discussion PD4 , PJ88 written first, second row is usually written on SX34E .
Diode PD5 Pj87 writing inscribed on first and second row iv meets function you mentioned that you were a suppressor diode , equivalent to P4SMAJ20"

Dont know if this helps

What is it next to, what is it connected to
If there are mosfets & a transformer near it, it may be a SMF51A which has a case code JZ (from the Romanian discussion) 51V transorb (transil) transient voltage supressor

[Steve L]

This may be helpful for some SMD parts. I cannot speak for its accuracy since I have not used it much.

SMD Codebook.pdf

Steve

[nevetslab]

The part is most likely a Transient Voltage Supressor as suggested. It sits just past a power supply decoupling stage on the daughter board of the CAT 5 switch. Circuit consists of a 2.4 ohm thermistor, a dual-inductor and a 100uF/100V electrolytic cap, with the TVS sitting across it. I assume it fired and failed shorted from some high transient that came thru and past the external SMPS 'wallwart'. That supply feeds +48V into the package. With the shorted TVS removed, everything powers up.

I searched thru other SMD code books, have a 2007 copy of the Tutura SMD Code book, but didn't find it in there. Searched thru On Semi, Vishay, Fairchild, Central Semi, Littelfuse, many others to see if I could find it, having selected the case size SMB, but never did find any PJ88's, or even PJ's listed. So, I put the system back together, handed it back to our IT guy for re-install....hope there's still enough protection with this TVS now absent. I don't know what would be an appropriate TVS part to install there, not knowing WHAT WAS selected. 48VDC is the nominal voltage, SMB is a 600W rated part (within it's time-dependent rating). Not sure just how to do non-destructive testing of any of the other PJ88's installed to see what it's characteristics are.

If anyone comes across that code and it's true identity, or know what would bypically be a suitable part for that function, I'd be pleased to know.

Thanks,

Steven

[mozwell]

Steven
We have a 100V cap, so the transorb has to be lower than that, and its on a 48V line, so it has to be higher than that.
Rectron transorbs P6FMBJ68 may be what you are after, its a SMB case, but the rectron data sheet doesnt list the code printed on the device
At a guess PJ68 are part of the rectron part number, so maybe its a 68V transorb.....
Is it possible the PJ88 is really PJ68 ?

Further complicating matters, PJ68 GS1G comes up in a search (chinese manufacturers), so thats just a generic 1A diode....
PJ is Diodes Incorporated 20V zener

In either case, a 68V transorb will perform the same as a 1A diode, it will clamp reverse voltages & clamp voltage overshoots.....

[gbono]

Edgewater Networks support : Support - Edgewater Networks outside chance they would supply a schematic or would identify the part off their BOM.

Counterfeit part?

[nevetslab]

Good sound logic in selecting a workable breakdown voltage rating for a replacement part. While my eyeballs are getting fuzzy, with the loupes on, it definitely is PJ88....like all the others on the PCB. I'll add some suitable SMB parts on my next parts order....I know my IT guy would feel better about it as well as myself.

Thanks,

Steven