For documentation purposes this is a Successful project to make a CS44A Phonak converter cable. Also see my Failed attempt to make a CS44A Phonak converter cable by Clicking -> HERE.
You need to start with a 6-wire cable, not a 4-wire cable. Note that this extension cable has the same connections as a computer keyboard or mouse. I got mine for $3.19 each from EBay user pcmicrostore. Here’s a link; http://stores.ebay.com/pcmicrostore
-tools needed- (multimeter) I bought this cheap multimeter at Harbor Freights for $2. Including the 9-volt battery!
-tools needed- (cutting pliers and (optional) wire stripper or some otherr wire stripper tool)
-tools needed- (soldering equipment with rosin core solder)
-tools needed- (heat shrink tubing to provide insulation over soldered joints)
-tools needed- (scissors to cut heat shrink tubing)
Test continuity/Ohms to prove that each of the 6 pins are connected. You only need 4 pins, but you need the correct 4 pins, thus start with a 6 pin cable.
Cut and strip the cable. You also need to cut away the foil/braided-wire shielding and strip the wires.
Test continuity/Ohms again to determine which color wire is connected to which pin. My results were 1=brown, 2=red, 3=orange, 4=yellow,5=black, 6=green). Pins 5 and 6 are not used for programming hearing aids so I cut those wires out.
Ready to solder. Note the small heat shrink tubing must be in place before soldering. Note that the larger heat shrink tubing (bottom of picture) must also be in place before soldering. You will need 4 hands or a soldering buddy. My wife was my soldering buddy (a term that she likes).
Soldering complete. CAUTION: The heat shrink tubing is very sensitive to heat. If you accidentally melt the tubing while soldering then you will need to take it apart to apply new heat shrink tubing. Note the connections for switching pins 3 and 4 (which you can see better in a later picture);
Pin1 brown-to-brown (same as it was before)
Pin2 red-to-red (same as it was before)
Pin3 orange-to-yellow
Pin4 yellow-to-orange
Apply heat to the small heat shrink tubing. I used a Bic lighter.
Slide the large heat shrink tubing over your splice area and apply heat to re-seal the cable.
Here are the DIY Phonak cable extensions connected between the Hi-Pro and standard CS44 cables. Note that Oticon programming cables #3 are standard CS44 cables. Thus, you could use this setup (with extensions) for Phonak and use CS44 cables without extensions for Oticon and other hearing aids.
Here are the DIY Phonak cable extensions and standard CS44 cables connected to Phonak Audeo IXs. The software (iPFG) can now detect, read, and re-program your Phonak hearing aids.
Let me point out that once you discover the the color of the wires for pins 3 and 4 this project becomes simpler. Using this particular brand of cable which has pin3=orange and pin4=yellow I can make another DIY CS44A by cutting only the orange and yellow wires and switch them to Orange->Yellow/Yellow->Orange without disrupting the other four wires.
This is a good post about making converter cables cs44 to cs44a.