_______________________________
/ \
| _________________|___
| \ 1o 2o 3o o o / DB9
| \ | o|7o| o o / Soldering side view
| \_|__|_||_______/
| | | ||
| ________________|__/ ||
| / ___________________|/
| | / |
| | | |
| | | ________________/
| | | /
| | | | D3 R1 4.7V
| | | `-->|---+-----+----/\/\-------+-------------------.
| | | 1N5819 | | 47R | |
| | | | | | |
| | | | | 1C1 |16 _ 4.7V
| | | | | .------+------, D4 ^ 400mW
| | | | | 2| VCC | |
| | | | `--------|v+ | |
| | | | C4 4| MAX |1 |
| | | | .--)|------|C2+ 232 C1+|--- |
| | | | | 1uf 5| |3 |
| | | | `----------|C2- C1-|--- |
| | | | 14| |11 |
| | | | C2 ---|232-01 TTL-11|--- |
| | | _ 13| |12 |
| | | @ 1uf ---|232-11 TTL-01|--- |
| | | | 7| |10 |
| `|----------|--------------|232-02 TTL-12|-------+----+---- MBUS
| | | 8| |9 D5 | |
| `----------|--------------|232-12 TTL-02|----|<-' |
| | 6| | 1N5819 |
| | ,------|v- GND | |
| | | `------+------' |
| | | |15 |
| | | | |
| | C3 @ | |
| | - 1uf | |
| | | | |
\______________|_______|_____________|________,__________/---- GND
V
https://www.petervis.com/electronics%20guides/Nokia%203310%20Customisation/serial.html