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.
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 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.
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.