Electronics > Beginners
Lets play name that smd component
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viperidae:
I'm trying to trace out the schematic for part of this board, unfortunately it's 4 layer.

I'm having trouble figuring out what this component in the SOT23-3 package in the bottom right corner is, marked with "563".
The traces connected to the 101 resistors are two data lines that connect to two other processors on separate boards.
I *think* the via's connected to the top (maybe...) pins goes to the +5V supply.

The data bus works by having some kind of pull-up and each processor pulls the lines to ground via a diode. On this board those diodes are *next to* L9002 and L9003.
The lines are read via the 103 resistors.
I think this is the board that supplies the pull-up for the data lines an I don't know how it works - if it's just a resistor or if it's a constant current supply or something.

My goal is to replace with board with my own. To do that I need to reverse engineer this proprietary communication bus.

For reference this is a display controller board from a Honda Internavi navigation system. It is also responsible for the communication between the navigation computer and (via this bus) the HVAC system and (via a different bus) the radio. The big chip in the middle is an OSD controller, the one to the left is some kind of video interface chip, the components on the bottom left are RGBS input related.
The other side of the board just has an RGB TFT controller chip and some flash rom for the OSD controller.
Off to the left out of frame is an NEC microcontroller, an IEBus controller chip for the radio data bus and a high voltage backlight driver.
helius:
Philips PZM5.1NB3 5.6V Zener diodes
Pete66:
Looks like
5.6V 300mW Zener

http://www.marsport.org.uk/smd/mainframe.htm

viperidae:
Now i'm confused... I thought those via connected to pin 1 were going to +5V, which means that's a forward biased zener feeding power into the data lines.
It would make more sense if pin 1 was ground, then it would be over voltage protection.

Back to square one.
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