Electronics > Repair
Identify chip L7c - Siemens kitchen appliance (oven) repair
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pplaninsky:
Hello,

It’s a control PCB from an kitchen oven.
The issue it lost comms with the user interface board on the front panel.

The chip is on the TX path of the data line (single wire for TX/RX running on 50Hz clock, generated from the mains).
The obvious purpose is to buffer that line as the other side is pulling the same wire to ground when transmitting.
[At least it’s what I think.]
However, it seems that at the moment this chip pulls down the line constantly to 2.3 volts, which is too low compared to the 5 volts level observed otherwise.

However, I couldn’t find any datasheet that matches the pinout.

Anyone - can you help me identify this chip?
suntime:
Hi,

Maybe it is: NL17SZ07DFT2G
https://www.lcsc.com/product-detail/Buffers-Drivers-Receivers-Transceivers_onsemi-NL17SZ07DFT2G_C113255.html

Regards.
pplaninsky:
Seem to match the pins and purpose.
Thank you.

I am wondering, if I can just temporary shunt the buffer - just to test the functionality of the PCB.

My guess is that if you connect just 2 devices, the sink current on the MCUs should be good enough.
This buffer is probably for over voltage protection and when you chain more devices
pplaninsky:
As I couldn’t find such replacement chip, I bodged a 7407 and used one of the six buffers from it.
Works perfectly.
fzabkar:

--- Quote from: pplaninsky on September 15, 2024, 02:51:09 pm ---As I couldn’t find such replacement chip ...
--- End quote ---

https://au.mouser.com/c/?q=NL17SZ07DFT2G
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