RS232-Port - solder to the NAS

From NAS-2000.org

On the mainboard of the the NAS2000 there is one RS232 interface which can be accessed through two connectors. It is not a full Serial-Port. There are only the Signals Rx, Tx, and GND.

1. CN6 4-Pin header with VCC-Pin 1 (3.3V), Tx-2, Rx-3, GND-4. The signals are 3.3V CMOS level and are connected directly to the CPU. Therefore you need an adaptor to get true RS232 level. Power for the adaptor may come from the VCC pin.

Do not connect directly to a RS232 without an adaptor! This may damage the NAS's CPU!

There is the possibility to build a simple adaptor by yourself. It is not fully RS232 compliant but it does it's work. The circuit is shown here:

You could take an old serial cable with the right plug on one end. On the other end you connect/solder it to your adapter.

2. COM1 is an unsoldered RS232-Port male connector with the signals TXD=Pin 3, RXD=Pin 2, and GND=Pin 5. If you want to use you have to solder a transceiver chip on the bottom of the board as described below. In that case CN6 cannot be used any more because the signals on CN6 are in parallel to U19!

The way is very easy if you have good eyes and a small soldering iron.

you need:

1x Maxim MAX3232CUE    (I ordered a sample by Maxim for free)
1x 9-Pin D-Sub Male Connector

On the downside of the mainboard solder the MAX3232 on the field with labelled "U19".

(picture is still missing!)

There is another solution to this! For fully function you don't need a 9-Pin-D-Sub on the board. you need:

1x Maxim MAX3232CUE    (I ordered a sample by Maxim for free)
1x 90° single row connector (Reichelt or your personal dealer)
1x old 5-Pin-CD-Rom-Audio-Cable ore something like this

On the downside of the mainboard solder the MAX3232 on the field with labelled "U19". Cut the 90° single row connector to the length of 5-Pin. Solder it from the top of the NAS mainboard like in the following picture:

(picture is still missing!)

Solder the Speaker-Cable to the 9-Pin Connector using the following scheme:

Connect Pin2 of the 5-Pin-cable to Pin3 of the 9-Pin-D-Sub (female)
Connect Pin3 of the 5-Pin-cable to Pin2 of the 9-Pin-D-Sub (female)
Connect Pin5 of the 5-Pin-cable to Pin5 of the 9-Pin-D-Sub (female)

(picture is still missing!)

Note:

The PC's serial port (9Pin-male) is RX=Pin 2, TX=Pin 3, GND=Pin 5.
For proper communication you need to connect NAS Rx - PC Tx, Tx-Rx, GND-GND.

Here are some pictures of the board and its connectors.