UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Wiring 'Aux-in' (iPod) connectors to Car radios

gfiandy · 30th Oct 2012, 6:01 pm

Just though I would add my experience modifying a much later unit and try and collate the information.
I bought a Radiomobile K200 new old stock for £16.
The plan is to modify it for a iPod and then replace the DIN mount unit.

Modifying it took ages as it needed quite allot of reverse engineering to work out the combined on/off tone and volume control, especially as the tone control feeds into the volume control carbon track. Very clever but confusing. Practical upshot was the iPod needs to be feed through the same input resistance as the radio section for the tone control to work. The control had three rows of pins, 3 pins (Tone) 4 pins (Vol) and 2 Pins (on off). I went through with a multimeter to identify what each set of pins did by changing the controls and identifying which control affected which reading. I also worked through the circuit and made drawing of what was going on.

Once I had identified what the circuit was I made a jack plug up with two 100R resistors to mix the signal to mono then a 33K resistor to feed into the volume control. This worked but cause the radio to pick up quite allot of noise from the iPod lead. So I introduced a micro-switch which is activated by tuning to the far side of the dial to switch between the iPod and radio into the volume control circuit. Problem is now solved, I also updated the lead I had used to a properly screened one.

Next problem was I did not have a radio plate to mount the twin spindle radio. Fortunately another forum came to the rescue and provided a drawing of the original item so I manufactured a simplified version in a bit of aluminium plate. It has no recess in it but this doesn't seem to be needed as there is plenty of space between it and the gear stick.

Currently the radio plate is just in the aluminium finish, I have ordered some sticky backed leatherette vinyl to cover it but decided to dry fit it to check it is strong enough and fits properly.

I have the reverse engineered circuit, I can't guarantee it is correct however it was good enough to do the modification, if anyone is interested it is attached.

Some photos of the modifications and the installation.

30th Oct 2012, 6:01 pm	#3
gfiandy Retired Dormant Member Join Date: Jan 2008 Location: Cambridge, UK. Posts: 8	Re: Wiring 'Aux-in'(iPod)connectors to Car radios Just though I would add my experience modifying a much later unit and try and collate the information. I bought a Radiomobile K200 new old stock for £16. The plan is to modify it for a iPod and then replace the DIN mount unit. Modifying it took ages as it needed quite allot of reverse engineering to work out the combined on/off tone and volume control, especially as the tone control feeds into the volume control carbon track. Very clever but confusing. Practical upshot was the iPod needs to be feed through the same input resistance as the radio section for the tone control to work. The control had three rows of pins, 3 pins (Tone) 4 pins (Vol) and 2 Pins (on off). I went through with a multimeter to identify what each set of pins did by changing the controls and identifying which control affected which reading. I also worked through the circuit and made drawing of what was going on. Once I had identified what the circuit was I made a jack plug up with two 100R resistors to mix the signal to mono then a 33K resistor to feed into the volume control. This worked but cause the radio to pick up quite allot of noise from the iPod lead. So I introduced a micro-switch which is activated by tuning to the far side of the dial to switch between the iPod and radio into the volume control circuit. Problem is now solved, I also updated the lead I had used to a properly screened one. Next problem was I did not have a radio plate to mount the twin spindle radio. Fortunately another forum came to the rescue and provided a drawing of the original item so I manufactured a simplified version in a bit of aluminium plate. It has no recess in it but this doesn't seem to be needed as there is plenty of space between it and the gear stick. Currently the radio plate is just in the aluminium finish, I have ordered some sticky backed leatherette vinyl to cover it but decided to dry fit it to check it is strong enough and fits properly. I have the reverse engineered circuit, I can't guarantee it is correct however it was good enough to do the modification, if anyone is interested it is attached. Some photos of the modifications and the installation. Attached Thumbnails