Trouble Identifing Zenor Diode on automotive ICU board

[Spiderman777]

Question\Help
I am trying to indentify few Diodes on an automotive ICU PC Board and as yet to find anything that even comes close to what in on this board. They appear to be bulb in shape with a grey ceramic body and Orange or Red band with a number printed on the grey side such as 3, or 7. The Icon on the board that it is soldered appears to be the solid black Zener diode symbol such as ---->S but I am having a hard time finding replacements for these that have broken loose at the ceramic part. These are from a 1994 pc board and was looking for some help\ direction on where online I can identify exactly what I am dealing with as I am not that familiar with electronic components such as what I am dealing with on this ICU board.

 

[Harald Kapp]

You have 2 possibilities:

• Find a schematic or Bill of Material for this board that tells you which zener to use. Or
• Find a working board (or someone who has one) so you can de-solder the diode and check for the actual value.

In my opinion no way to tell from the diode housing alone.

 

[Bluejets]

If there are any intact, one could test out of circuit with a component tester such as shown below.
Less than $30.00 and a good tool to have onhand, not only for diodes.

 

[Harald Kapp]

A nice little tester, I have one, too. Really easy to use. About $ 10 from China as kit version.

 

[Spiderman777]

Understood, but these boards are long dealer discontinued and far and few finding any used online and MANY Honda Acura owners are at a total loss and I am surprised no one thought or reaching out to the experts here for advise. Since this is the case for many remaining Acura Legend car owners from 1991 to 1995. Some are working to reverse engineer this board but the 1st major roadblock is the OKI IC. I was thinking same thing regarding testing a fully fuctional one and should have a used one similar but not specific for my Models features but it should have those similar components and figure its worth a try for $20 especially when these Honda ICU modules ran over $500 from the dealer in the day. I appreciate the responses here and glad I found this site. Much thanks for all your inputs here! James

 

[kenny256]

Can you measure the length and width of the glass bead--that will help determine the size, e.g. SOD57, etc.

Here's a link to Vishay datasheet: https://www.vishay.com/docs/85599/bzt03.pdf

 

[kenny256]

Are you able to measure the forward diode voltage drop with a meter diode test function? Even though the lead broke off at the bead, it might still conduct in the forward direction and you could get a reading. Try measuring all of them to get a comparison of data for all the zeners with similar markings.

If you wanted to remove one that is good or that conducts even with broken lead, then mail it to me and i will measure the zener voltage on a curve tracer. Here's an example measurement for a jfet that i did for a fellow.

 

[Spiderman777]

I think it would be best sending you the diodes to you as I am dead in the water and could use the help!

 

[Martaine2005]

I think it would be best sending you the diodes to you as I am dead in the water and could use the help!

Wow, a reply exactly 6 months to the day!!
If I'm honest, you could have replied a lot earlier.

Martin

 

[kenny256]

Martin, you don't know what has happened in his life with respect to job, family, pandemic, etc. so to be honest you don't really have any basis for your statement that he could have replied earlier. Why post crap like that which helps nobody and answers no questions? Better late than never, i'm still willing to help.

You just made the list--members to ignore...

 

[Martaine2005]

You just made the list--members to ignore..

How very grown up of you.