9two8

Can someone tell me where the radio fuse would be located on my 80my 928 S Blaupunkt Melbourne. The radio/cassette has stopped working, ie, zero illumination and the electric aerial that usually extends via radio switch no longer functions.
I looked in my fuse diagram and my year car doesn't show any radio fuse listed on the fuse board ?

Note, I have not done any electrical or other work in the vicinity.

Ken
80 928 S
5 Speed
UK

dr bob

Without booster:

The electrical diagram for your 1980 car is less than specific on this. The diagram shows an inline fuse downstream of an inline suppressor, with power source described as "ignition/starter switch (r)". The fuse is not shown in the fuse panel. The color code for the wire from ignition switch to suppressor, and again suppressor to fuse, is red-with-black-tracer in 1.0 mm^2 size. No color description for the conductor from switch to radio. This is the ignition trigger wire that tells the radio it's OK to operate.

The primary power to the radio is via CE panel connector F4, red 0.5 mm^2.

With booster, the circuit adds power via the rear wiper circuit and fuse 15, a 16A fuse with feed directly from circuit 30 and battery positive. 2.5 mm^2 conductor feeds the booster, which then supplies power to the radio unit. This still has a suppressor before the booster, plus the suppressor and inline fuse for the head unit as described above.

----

For what it's worth, I've found the wiring diagrams for my later (1989) car less than precise around the audio system. Keep that in mind as you trace and troubleshoot the system. I wanted to leave all the factory wiring intact and unmolested when I upgraded the head unit and disabled the booster. I ended up with a mating conector for the harness to pick up the ignition-on signal, while all the rest of the factory power supply wiring is no longer used.

9two8

Thank you, I have removed the radio and found the 2amp inline fuse is blown, and as you say there is a little "black box " thing a couple of inches along past the inline fuse, untill I get a replacement fuse I can't try it to see if it fixes it, there's another fuse built into the end of the set which says 5amp, I removed that and it was intact. Unfortunately these type of electrical faults are a bit above me, however a good friend of mine an ( Auto electrician ) has promised to have a look at it for me later this week, so hoping he can find any problem that just a 2 amp fuse won't fix ?
Once again thank's and I will show him the advice you have posted, very helpful indeed.

Ken
80 928 S
5 Speed
UK

dr bob

For future browsers:

The wiring diagrams show a "radio prep" option which has nothing more than the 4 speakers pre-installed and wired. The two radio options are head unit without booster, and head unit with booster. In both, the power for the head unit is shown but the actual connections to power buses in the CE panel are left out. For cars that have the added booster, there is a primary connection as mentioned in my post above, but still no source for the ignition-switched wiring to the head unit. That would most typically come from bus X in the CE panel rather than the ignition switched (15) bus mentioned but not diagrammed.

It almost looks like the audio packages were intended to be dealer-installed, where the installing tech had some latitude in where he grabbed ignition switched power. I can't think of any other reason why this connection would be left out.

9two8

Well I got some 2amp glass fuses, tried one in and no dice, look's like I'll need my auto electrics guy to help out,, last time I used the radio, it worked as normal including the mast lowering and raising from switch on, zilch from either now ?

Ken
80 928 S
5 Speed
UK

dr bob

Try unplugging the antenna power from the head unit, and see if a new fuse survives. A short in the antenna or wiring can blow a fuse easily. It's quick troubleshooting for the cost of a fuse.

9two8

.., I will be away from the car till end of week, good info again. Hopefully keep you posted !
Thank you for your help.

Ken
80 928 S
5 Speed
UK

9two8

Finally got my radio/cassette back today after repair, turned out the problem was a faulty chip and capacitor causing fuses to blow.



Ken
80 928 S
5 Speed
UK

dr bob

9two8

Your certainly right there, old guy I finally found was almost 70, A friend told me about him tucked away in a little alley way office upstairs, with an amazing range of different radio stereo sets that he's collected over the years almost touching the ceiling, I did notice a touch of OCD with him as his desk and other things on it were meticulously set out in order. All he wanted to do was talk about the old days and how his trade had changed beyond his recognition and frankly his caring.
He was quite impressed with the overall condition of my Melbourne model, telling me more than I ever knew about the brand, and saying that this model was the flagship model of it's day costing around £500, about $670, and this was around 1985.
Anyhow it's all fixed (fingers crossed) for now thank's.

Ken
80 928 S
5 Speed
UK