http://www.hifi-remote.com/wiki/index.p ... Interfaces
Chip_partner is no longer selling FTDI FT232RL cables, but other FTDI cable should work instead.
Another option a Prolific PL2303HXD USB to RS232 TTL Cable. This cable usually has a pink casing. It comes with a 1*6 solid DuPont connector, which will need to be replaced with a 2*3 connector.
The key to searching for cables yourself is to check that the RTS line is present, which usually means you need a 6pin cable.
 
The pin codes for these cable are (NOTE: colors can vary in different cables):
pin - type - color
1 - (empty):VDD
2 - RTS (usually Yellow)
3 - GND (usually Black)
4 - TXD (usually Green)
5 - (empty)
6 - RXD (usually White)
CTS (usually Blue, not connected)
5V (usually Red, not connected)
Special note: If your remote has a 24-pin S3F80P5X chip, like the URC-2020B0-B1, URC-2025, URC-2060BC0 and URC-625000-04R00, connect the RTS line to pin1 instead of pin2, and take the batteries out of the remote when programming it with RMIR. (More info: here).
If your cable has pink and grey wires, this might be the pinout:
Red 5v
Black GND
White RXD
Teal/Green TXD
Pink CTS (instead of blue)
Grey RTS (instead of yellow)

For remotes with a 5-hole connector (like the URC-2025):
[NOTE: remove the batteries while using RMIR]
1 - RTS (usually Yellow)
2 - (empty)
3 - GND (usually Black)
4 - TXD (usually Green)
5 - RXD (usually White)
If you need to make it work with older EEPROM based JP1 remotes, you'll need a DIY Gadget JP1 EEPROM programming adapter $18 (+ $4 shipping):
https://www.diygadget.com/remote-contro ... p1-adapter
These adapters usually do not have pin1 marked. To find pin1, feel the adapter over the heat shrink tubing and you'll notice that one side is flat whereas you can feel the components on the other side. Looking at the flat side, pin1 is marked with white dots in this photo:

You can also use an Arduino cable as an EEPROM adapter, details here:
http://www.hifi-remote.com/forums/viewt ... p?t=102890
http://www.hifi-remote.com/wiki/index.p ... er_remotes
If you want a 6-pin plug for the end, click here (select 2x3P, 6 pins):
https://www.ebay.com/itm/304102714605 (10 for $10.17, US shipping)
https://www.ebay.com/itm/263051820184 (40 for $4.94, China)
To remove the existing Dupont connector, use a blade and pop up the plastic tab over each connector and then pull the wire out. With the new connector, just slide each wire into the appropriate slot, with the connector tab facing up so that it pops out of the little window.
The following pic shows how the pins are numbered for the 6-pin connector in the remote itself:
 
This video shows you how to connect the cable:
https://www.youtube.com/watch?v=cLYzsh-usTo
See this for other cheap cable sources:
http://hifi-remote.com/forums/viewtopic.php?t=16200
