There are 3 connectors that interface between the modem board and the the main board.
 

CN5	serial connection to the modem
1	DSR
2	CD
3	RTS
4	RXD
5	CTS
6	TXD
7	RI
8	DTR
9	not connected
10	not connected
11	GND
12	not connected

CN7	this connector leads to the 2 telephone jacks
1	phone tip
2	line tip
3	not connected
4	line ring
5	phone ring

CN9	power connector
1,2	+5V
3,4	-12V
5,6	GND
7,8	+12V

The hack is basically a ribbon cable that connects between CN5 on the main board of the cable modem and your external modem. On one end, we have a 12 pin (or greater) IDC connector, and on the other end, a 9 or 25 pin D-sub. The internal 14.4Kbps modem is no longer used, and can be either removed, or left inside.

Here are the pinouts for 9 and 25 pin connectors:

CN5 on the main board	Description	9-pin dsub	25 pin dsub
1	DSR	6	6
2	CD	1	8
3	RTS	7	4
4	RXD	2	3
5	CTS	8	5
6	TXD	3	2
7	RI	9	22
8	DTR	4	20
9	not connected
10	not connected
11	GND	5	7
12	not connected

I cut the end off of a joystick port connector and used the ribbon and 16 pin IDC connector.
There were rows left open at the end, but that was ok. Soldering this to a 9 pin male dsub
is recommended because most of the wires line up and fall right into place.

After you are done, plug the connector into your external modem, plug your phone lines, network lines, and
cable lines into the whole contraption and then power cycle your HYBRID CCM-202. You
should hear it dial in and then you are ready to upload 2-4x faster.

 
 

CCM-202 Hybrid Cable Modem

see the boards again ->