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Japanese import FM tuner conversion

nzlamb

This post describes how to modify a McIntosh PF-2142I (often but incorrectly referred to as PF-21421) JDM car radio to natively tune from 87.5-108MHz as used in most countries around the world. This model of radio is fitted as standard equipment in many JDM Subaru Legacy and Outback cars manufactured between 1998 and 2003.

Most Japanese domestic market import car radios are designed to tune from 76-90MHz which means they will not work natively in any other country. You can of course buy a so-called band expander but these usually result in nasty RF harmonics, poor reception and reduced sound quality. They also still restrict you to a 14MHz segment of the 20MHz public FM band and don’t display the correct frequency on the radio. This modification allows the radio to tune local station and display the correct frequency without the need for a band expander!

Update: I’ve also added a more generic guide here.

The information here certainly applies to virtually any Clarion or McIntosh JDM radio using a Clarion 80-2082AT tuner module. I’ve also successfully applied this to the Clarion PF-1572I and PF-2143I as well. Most minidisc players are designed specifically for the JDM only and cannot be modified.

This modification works because Clarion (and other manufacturers) often produce a base head unit design for the international market. The FM band it can tune is simply set by using a specific tuner module and setting the right jumpers to match. While I’m sure I’m not the first person to have figured this out, I dare say it’s the first time someone had decided to publish this information freely on the internet!

What you need:

If you are modding a McIntosh like this one you will also need a suitable amplifier for bench testing as the stereo does not have one inside it. Any type will do; simply use pins 1 and 3 for audio and 6 for ground on the 13-pin audio output connector.

Disassembly

Remove the top screw and pry the top cover off using flat screwdriver in each of the four slots. Do the same for the bottom cover.

Remove the volume and fader knobs followed by front panel. It is attached via two black clips on each side. Use a small flat screwdriver to push these inwards and carefully slide the panel off. Try to do this evenly to avoid damaging the connectors.

Disconnect the ribbon cable from the front then remove the four screws holding the CD player module in. These are the top two screws on each side of the unit. Lift the CD player out from the top.

Remove the screw from the each side of the lower rear panel. Leave the panel in place for now.

Remove the remaining two screws on each side of the unit. The outer sides and upper rear panel should now lift off the base in one piece.

Undo the four screws holding the cassette desk in and carefully lift it out.

Modifications

Locate the area selection jumpers. Move the jumper shown in the photo to select area 2 (NZ and most other countries). Move the jumper to the right instead instead to select area 1 (North America). The rest of the modification is the same regardless of area.

Desolder and remove the metal bracket that runs across the middle of the PCB.

Desolder and remove the tuner module. This is quite difficult and time consuming! You may need to loosen the volume pot in order to get the tuner out.

Replace the four varicaps on the tuner PCB with SVC203 types. The original varicaps usually bear the marking V4 or F0.

Desolder the tuner shield and remove it.

Locate the small black coil shown in the photo and desolder it.

Note that it has three terminals; only two are used. Cut the wire leading to the top of the coil and remove one and a half turns. Solder the wire to the previously unused terminal. Solder the coil back in place. The photo below  shows the modified coil installed back into the tuner.

Reattach and solder the shield to the tuner. Install the tuner back onto the main board.

Testing and Adjusting

I’m not exactly a radio buff so here’s how to adjust the radio the kludgy way without any fancy test instruments! If you are a bit more clued up in this area you might have a better way of doing this.

Attach the front panel being careful not to damage the two connectors. It should sit in place without any additional support but be careful not to knock it.

Connect power, an amplifier and an antenna to the stereo and confirm that the FM tuner now searches the frequency range you expected. Try auto seeking for an FM station. The tuner should do this quickly but may not lock onto a station by itself at this stage. If it suddenly slows down you need to retune the coil in the tuner as described in the previous section. Remove more winding to shift the reception up the band.

If all is well tune manually into a local station and confirm it sounds OK and gets stereo reception.

Mark the position of the top coil indicated in the photo. Tune into a known weak station. Slowly adjust the coil until the signal appears to be at its peak. You will probably find this is close to its maximum clockwise position. Be careful not to over  tighten it as it is very easy to damage; the moment you feel the slightest change in resistance on the screwdriver you have reached the maximum.

Now try seeking stations. You may find this works OK for strong stations at the lower end of the band and then gives up. Use a small plastic object to widen the gap of the lower coil marked in the photo. Do this in small increments until the radio seeks properly across the entire band (or as much as possible).

Once down, power cycle the radio and confirm it still appears to operate at its peak performance and that the stereo indicator comes on when you tune into a sufficiently strong station.

Once you are happy with the radios performance, take a moment to rework the solder joints where the metal chassis components are soldered to the PCB, and also the joins on and around Q408, Q423 and Q424 as these can often crack a little over time.

Finally I’d recommend checking that all of the features (CD player, controls, backlight, etc) still work as expected before installing it into a car!

If you install the modified radio into a Japanese import car the reception may not be as good as you would get from a car produced for the local market. This is because the antennas in JDM cars are usually tuned for the 76-90MHz range and often use horizontal polarisation.