DAB Radio Upgrade

Thanks to Bryan Barker for this one. (The process he describes works for other makes and models of 1-DIN head unit).

Note - section MH of the service notes deals with the post-86 wiring loom.

This article describes how I fitted a Blaupunkt Bremen SQR 46 DAB Radio, having already upgraded the speakers to modern Alpine items.

Not cheap, but it ticked the boxes of:

1. Having the proper 80s / 90s OEM appearance - the similar looking Blaupunkt Cambridge was certainly on the options list for the Excel around 1987. I believe the later cars may have gone over to Clarions.

2. Having illumination that could be adjusted to match my green dashboard lighting.

Plus of course all the mod cons of DAB and FM RDS radio, Bluetooth phone & streaming, USB & SD Card playback, etc. etc.

One thing I wanted to avoid if possible was the unsightly DAB antenna stuck to the windscreen. After consulting some other owners, it was pointed out the since our car's shell is non-conducting, the antenna could be stuck anywhere inside. However one owner had had success using a DAB / FM splitter / amplifier, which uses the existing FM aerial, and consists of a small screened box which sits behind the stereo - not a space issue since the Blaupunkt (which doesn't have a tape or CD drive) is shallower than the old Panasonic stereo. So I decided to go with this. The shopping list consisted of:

The stereo comes with a mounting cage, a remote (wired) microphone for Bluetooth calling, a remote control, and 2 connectors with bare cable ends, one for power etc., and one for the 4 speakers.

The DAB splitter has an SMA type DAB connector, so it is necessary to buy an SMA / SMB adapter to fit to the stereo. There is another splitter on the website which has an SMB connector already, but it is the wrong gender for the Blaupunkt.

The old Panasonic stereo (also about 1990 vintage, more on this later) came out without too many troubles, I had to move the gear lever back into 2nd to get it out. Thankfully it revealed a professional installation job, using in-line crimps for the speaker cables and bullet connector adapters for the power. Also 2 ground cables screwed directly to the rear casing of the unit.

All the cable colours were as per the Excel MH wiring diagram, with purple being the permanent 12V and yellow being the ignition switched 12V. The Blaupunkt takes its power from the permanent feed, but both need to be connected. It has some clever functionality in that you can switch the radio on while the ignition is off, but it will only remain on for 1 hour to avoid a flat battery.

The quiescent current draw of the unit from the permanent feed is only a couple of milliamps, so nothing to worry about. When the ignition is switched on, the radio will remain on until you turn it (or the ignition) off. Apologies for the appearance of an (unused!) covid mask in this photo, as the old stereo slid out, it brought 30 years of car grot with it - so I grabbed the first thing I could reach in the glovebox in order to put the unit down without marking the leather!

I cut all the connections back to bare ends, leaving them as long as possible, and removed all the Panasonic mounting cage, wiring, crimps, etc. I stripped the wires back about 8-10mm, and checked the phasing of all 4 speakers from their terminals to the bare ends, all were correct. If you have one or more speakers "out of phase" - i.e. connected backwards, the sound will be very thin and the balance control will not work correctly.

Generally the larger terminal on the speaker itself is deemed the positive. I soldered the supplied speaker connector (with its bare wire ends) to them, and added heatshrink sleeving over the joints. I very carefully used a heat gun to shrink the sleeving down, while protecting the dashboard behind with a cloth.

The connections to the power connector (yellow, purple, and black cables) were made similarly, remembering to disconnect the battery first. However there are a couple of extra connections to be made to this connector. One is the power to supply the DAB splitter, which has an active amplifier that requires about 40 milliamps when the radio is on. It has a blue "12V supply" cable, which is connected to the blue "Antenna Power" cable on the power connector. This cable was originally used to activate an electric aerial, but in this case is perfectly suited to supplying the DAB splitter.

The other extra connection is for the illumination. The Blaupunkt unit has two presettable levels - one for daytime driving, and one for night time. It switches to the night time level when a voltage (anything over about 1.5V) is applied to the "illumination" cable. The question was where was I going to get a suitable feed from. Luckily, the cigar lighter is illuminated by a single bulb in a holder. By feeling around through the radio slot and upwards, I found the holder at about the 4 o'clock position when you look at the lighter from the front. Pull the connector backwards (i.e. towards the front of the car) and the bulb + connector will slide out. I managed to splice in an additional length of cable to the red + white stripe illumination cable, and ran this to the illumination cable on the supplied connector. Remember to leave plenty of length in this cable since it will have to run around the back edge of the new radio cage when it slides in. Splicing in this cable was the fiddliest part of the installation.

I connected everything up (including the antenna connections to the DAB splitter, which are self explanatory when you see them) and hit the power button. Fortunately, everything worked first time!

I provisionally sited the microphone (supplied with its own self adhesive pad) on top of the steering column, where it is fairly discreet, and it was easy to run the cable behind the dash to the 2.5mm jack socket connector on the back of the stereo. I'll experiment with the exact positioning of the mic to get the best pickup, before sticking it into place.

I disconnected everything once more, and slid the mounting cage into the aperture. Initially, it wouldn't fit because the aperture was about 1mm too narrow, so I had to file it out slightly. After reconnecting for the final time, all the wiring (now tidily bundled using felt tape) and the head unit slid back into place with a satisfying click... :)

Soundwise, the unit was pretty much as expected. Very clear, but like the old Panasonic unit, not a massive amount of bass due to the smallish speakers I fitted behind the OEM grilles. Tweaking the loudness and EQ settings improved things. It does have a subwoofer output should you decide to add one later. The reception on DAB and FM appears very good. I paired my phone with it easily, although the small 80s style display makes using the phone book / contacts a bit fiddly. You can't have everything! I set the illumination to green and tried to match the brightness of the dashboard, all in all I'm very pleased with the result.