Hi there, first post here so thanks for letting me join, and apologies in advance for what are some dumb questions from a diesel mechanic. I have a Scania truck air suspension control unit that is only partially working. I have opened it up and identified the fault but im having trouble finding the components to repair it. I have spoken to a number of electronic component distributor's but no one could give me a definite answer. The only markings on the smd components are RJ 91 and the Vishay symbol. It does have a line at one end like a diode but I need to be sure I get the correct parts as Im at the edge of my comfort zone here

 

It looks a lot like a diode. Similar to other Vishay diode pics i found online.

 

Welcome to AAC!

Couldn't find anything in my SMD references. Have you tried contacting Vishay?

The polarity marker could indicate a capacitor or diode. How many leads does the device have? What makes you think it's bad?

Do you have a schematic for the board?

You should contact a moderator and try to have your member name changed. It doesn't take too much of a leap to see that it's an email address.

 

Check the physical size of the diode and compare with Vishay RS1J, RS2J, and RS3J diode.

https://www.vishay.com/docs/88707/rs1a.pdf
https://www.vishay.com/docs/88708/rs2a.pdf
https://www.vishay.com/docs/88709/rs3a.pdf

http://matthieu.benoit.free.fr/cross/competitive/general_semi/marking.pdf

 

It's a diode, made by general semiconductor (now Vishay as you pointed out). Look:



Here's the datasheet

https://www.vishay.com/docs/88697/rgf1.pdf

Yours is (I think) RGF1J, manufactured in Jan 2009.

Here's the docs for the marking variants

https://www.vishay.com/docs/88912/diodesgroupbodymarking.pdf

 

Hey guys/ girls thanks for getting back to me so quickly. The problem I have is that I found a data sheet with the RJ on it, but vishay called it a "surface mount fast switching rectifier" whatever one of those is? I cant get hold of Vishay and nobody in Australia seems to carry their range. I'm in remote northern Western Aus So I need to be sure I order the right things before I wait for freight. There are 5 of these on the board and some have flow both ways and some don't and one has no flow either way. I have a tester that allows me to test on the board. I don't have a schematic for the board as auto manufactures keep that a closely guarded secret and replacement involves programming the ecu to operate in the can bus system which is expensive and difficult given our location. I have done maybe 75 similar ones over the years and only failed on one which was too badly damaged due to an electrolyte drink getting into the box

 

I have a tester that allows me to test on the board

In-circuit testing doesn't always give reliable results. Only the diode that doesn't conduct in either direction might be a correct indication. Removing to test would be more definitive.

 

I cant get hold of Vishay and nobody in Australia seems to carry their range.

standard recovery diodes recover in about 1ms. this is fine for mains frequencies.
fast recovery diodes are some 10x faster.

surface mount is type of package format (no leads).

since actual rated voltage is not clear, go with higher, specially since you may only use couple of them and the price difference is negligible...
standard electronics suppliers carry Vishay product. they are literally everywhere, apparently down under as well...

for example:

https://www.digikey.com.au/en/products/detail/smc-diode-solutions/RS1K/5993443

https://au.mouser.com/c/?q=RS1K&_gl...T*MTcxOTE4NTAzMi40LjEuMTcxOTE4NTM2OS41Ni4wLjA.

 

First question is why do you think that the diode is failed??What test have you done?? What is the symptom in more deatil thatn "Not working."