Hello All,

I had the same problem as the previous thread.
Can u help me, what is type number of this diode zener with marking " MMM. "?
see the image attachment

thanks.

 

I get no hits on my cross reference. What makes you think it is a zener diode?

 

it is part of a series of communication and connect with MCP2551 IC.
(-)Zener to pin5 and 6 of the MCP2551.

 

CORRECT: .......... (-)Zener to pin 6 and 7 of the MCP2551.

 

What are they doing with a zener in those positions of a CAN transceiver!!??

Pin 6 is CANL, it should be connected to nothing but the bus.
Pin 7 is CANH, it should be connected to nothing but the bus.

A terminator if it exists should be on the cable and not on the PCB of ANY node.
Especially bad is a terminator on the PCB with a JUMPER.

The unit will work just fine without them.

 

The only search results I got were, "24V bilateral MOV".
I think that would fit in your position from CANH to CANL but I have no background in that area.
Refer to Papabravo for better information than I can provide.

 

thanks for your time.

I just saw on the same circuit, may be just the previous model.. MCP2551 connected with a zener diode SOT-23 with marking "EL15" = ESDA14V2L, and it's for ESD Protection.

I wonder,the zener diode breaks down all on the PCB.
I read the datasheet "High ESD protection level : up to 25 kV"

you have a recommendation for replacement parts?

 

CORRECT: .......... (-)Zener to pin 6 and 7 of the MCP2551.

Have you noticed that there is an "Edit" button on your threads? You can make corrections in the original post. Its usual to make a note at the end, stating why you made an edit.

thanks for your time.

I just saw on the same circuit, may be just the previous model.. MCP2551 connected with a zener diode SOT-23 with marking "EL15" = ESDA14V2L, and it's for ESD Protection.

I wonder,the zener diode breaks down all on the PCB.

Does the PCB have a symbol printed on it? Can you provide a picture? Does it look like this:

Then it is a varistor, not a zener diode.

 

Have you noticed that there is an "Edit" button on your threads? You can make corrections in the original post. Its usual to make a note at the end, stating why you made an edit.



Does the PCB have a symbol printed on it? Can you provide a picture? Does it look like this:

View attachment 83313 Then it is a varistor, not a zener diode.

no,just"DZ.."