Diode identification and car radio repair

SMD markings are difficult because of lots of duplication between manufacturers. It might be this [best to trace out the circuit around it and see if it makes sense with the part in there]

https://docs.broadcom.com/doc/AV02-1320EN

both HSMS2823 and HMS282E use 'C3' code [package size is different, so you could tell which by measuring].

I would not have to high hopes that replacing that diode will fix the problem.... but as it is an easy thing to do if you (or a friend) have a multimeter and basic soldering skills. So it sure is worth to try.

I did not find a perfect match for the marking code. There are a few dual diodes that start with C3 (or C30). The 08 could be a date code. But in this case you are lucky that there are more diodes of the same type mounted on the PCB so you can measure if the diode configuration is either "common cathode" or "serial" with a multimeter that have a diode test.. You could probably measure directly on the PCB, or de-solder it to be safe. The diode test should also show if it is a schottky or silicon diode.

I do think that it is enough to replace the diode with any general purpose diode that have the same configuration and type (eg common cathode schottky in sot-23 package) to see it it works.

It is a good idea of replacing the diode with the general purpose diode. Hope it will work.

Hi guys,

Well I measured the 3 terminals of the diode and only the 2 that are beside each other resulted with continuity. I also noticed that the continuity is because they are both grounded. Another thing I noticed is that the marking is actually "C30B" I mistaken the B for an 8.



Sorry for my bad diagram. So I'm not sure if this part is actually a diode at all. But as Fredrik Andersson said maybe is not worth it to replace this irrelevant part and I should be searching for something more specific.

I think my next step is to identify every IC on the board and then try to find their specific datasheet to figure out if they are doing what they are supposed to.

edumcg I did a little snooping and came up with this link
~~ Cris H.

Thank you very much Cristina! Unfortunately it appears like my radio model number is not there, maybe they developed the radio specifically for Nissan and not for general audience.

Still I am looking for a similar radio in their DB to check if I can find something useful.

Attaching a picture just for the record.

The only thing to be found is by this link

c30B - SmdCode Search - Marking Codes

Hope this can help

edumcg a quick email or call wouldn't hurt.

~~ cris

I don't wish to rain on your repair parade but, I question the suggestion the component D402 (A) is a diode. Diodes typically have two leads and not three leads as D402 has. D401 (B) could be a diode and ZD402 (B) could be a zenor diode (guessing because of the prefix Z). This two component have two leads. D304 & D303 (C) are diodes according to the symbol. Component D305 (D) might be a diode. It is fairly large and just two leads.

There are transistors, I suspect the components prefixed with a Q,  that typically have three leads. D402 having three leads causes me to question if in fact the components is a diode. Maybe someone with SMD experience can chime in on the call.