Radio Mystery - solved

[zorruno]

Hi Andrew

My radio/cassette (1990 Panasonic) suddenly stopped working .
...there were sparks from the earth cable when I touched the back of the

radio.

Also when I plugged the power into the radio the tape made a whirring

noise.

umm - a multimeter is only $10-$20 - sparks - not good! A multimeter is
also useful for checking fuses, current, etc etc

The fuse inside the radio was fine. ...Noises from the cassette but no

lights.

correct - I've seen this a couple of times

So the 'cigar 15A ' fuse looks after the radio part, and the
'room 10A' fuse looks after the cassette part.

not quite true - but that's how it would seem.

a) The 'room' fuse looks after permanent 12V for radio memory and most other
functions when running.
b) The 'cigar' fuse only has power on whilst the key is on (or ACC) and for
some reason either powers motor drive functions, or there is power back-fed
to the these functions if a) is not present

what you would have probably been experiencing is a blown 'room' fuse (you
don't say which one was dead, but that's what I'm guessing - was it a blue
one you replaced?) which would mean your radio would have power via the
'cigar' circuit, or only when the key was on - but nothing via the 'room'
fuse for vital power functions.

- a bit of a design floor really - as it confuses the %&@@ out of people if
a room fuse goes and they power up the stereo. Most other aftermarket
stereos will do nothing at all if either one of the fuses gos.

My haynes manual is on loan at the moment, but I think their is only one
radio circuit for all Mk1 models. I know my 94 was like this. I have a
copy of it here
http://www.mx5club.org.nz/downloads/spe ... diag_2.gif . A circuit
diagram does wonders for solving electrical problems...!

cheers
zorruno