No radio

[Graeme Head]

I need help... largely thanks to this website...

After reading your section on headrest speakers I decided to buy and install
some, as my 1990 version had none. I found some 3" round speakers at
Surplustronics at the top end of Queen St, City. I wired the first 2 speakers in
and had them running fine, a great improvement in sound. As I disconnected the
headrest speakers so I could properly tidy up the wiring to them and do some
surgery to the seat foam where the speakers sit, I heard a click and the radio
went dead - the clock part also. I know I'm probably a dunce for not turning the
head unit off before I disconnected the speakers, but I can't get the darn radio
to go again. ( Its the factory fitted Panasonic radio )

I have checked all the fuses and have also removed the radio, in case there was
a fuse in the back of it, but can't see one. The miata garage website wasn't
too much help with info on this problem ( but excellent in terms of instructions
for how to remove the radio). I did read somewhere that there is a built in anti
theft code on these radios. Would my radio have thought
that it was being stolen and thus 'terminated' itself, or what?? Any idea on the
'universal code' to get it going again?? Is there anything I may have
overlooked? My cat was playing in the drivers footwell at the time of the click,
but I've checked for any wires he may have pulled out and nothing.

Before I make a probably expensive trip my friendly Mazda service man, can
anyone help? The southern motorway is getting a bit dreary and I've exhausted my
humming repetoire.

Graeme
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[Lindsay Vette]

I managed to confuse my (non-standard) radio by turning it off immediately
aftrer turning it on one day with the same result. After pulling and
checking all the fuses it came back to life - I suspect because it was
isolated from the power source for long enough to reset itself.

You could try disconnecting the battery for 30 seconds to see if you get the
same result.

Regards,
Lindsay

[zorruno]

OK - I'll have a stab...

I found some 3" round speakers
I wired the first 2 speakers in
and had them running fine, a great improvement in sound.

what were the specs of the speakers - power handling? impedance??
did you put your own wiring in? if so how did you wire them? Right seat
left speaker and right seat right speaker in series or parallel?
Or was it the existing factory wiring?

If impedence too low (should be 4-8 ohms seen at the stereo input I suspect)
you will soon destroy the amp in the unit. Two 4ohm units in parallel = 2
ohms. not good for factory unit. Power handling less than about 10W RMS (or
20-30W peak) and the speakers may give up (shouldn't cause your stereo to
die however). I'm not sure how the factory HR speakers are wired - my
manual is at home, but I guess it would be two 4ohm speakers in series
(=8ohms) for left and right channel.

You'll probably notice if your impedence is too low anyway. The amp will
try and compensate, and will be much louder in the headrest speakers than
the doors (until the amp chip overheats and dies or a fuse/cct breaker
pops). Your front/HR knob will be over to the HR more. Note that some amps
are designed to handle low impedances (sometimes less than 0.25ohms) This
one is not.

Also some amps are designed so that their left and right inputs are floating
so you can bridge the left and right channel for more power (but a mono
signal) I very much suspect this one is not. Make sure no leads are
crossed from one channel to the other.

As I disconnected the
headrest speakers so I could properly tidy up the wiring to them and do some
surgery to the seat foam where the speakers sit, I heard a click and the

radio

went dead - the clock part also.

the clock part of the stereo? so there is no lights/display on the stereo
at all? This means it is dead sorry. A click and then nothing doesn't
sound good. (However, at least it wasn't a bang, followed by smoke, and then
nothing)

I know I'm probably a dunce for not turning the
head unit off before I disconnected the speakers, but I can't get the darn

radio

to go again. ( Its the factory fitted Panasonic radio )
I have checked all the fuses and have also removed the radio, in case

there was

a fuse in the back of it, but can't see one.

Are you SURE there is not still a short in the speaker wiring? Modern car
amplifier circuits often have resettable circuit breakers in the outputs, or
current limiters (sometimes built into the amp driver chip as the amp is
usually one ) so they shut down if you try to drive a short. Others have
fuses in the output circuit or power line - sometimes external, but often
internal to the stereo. If you remove the short, it is POSSIBLE that it
might start up again.

I also seem to remember a 10A blade fuse inserted in the back of the factory
unit, but that could have been in my MX6's unit (that I also removed within
1 week of owning it...)

The miata garage website wasn't
too much help with info on this problem ( but excellent in terms of

instructions

for how to remove the radio). I did read somewhere that there is a built

in anti

theft code on these radios. Would my radio have thought
that it was being stolen and thus 'terminated' itself, or what?? Any idea

on the

'universal code' to get it going again?? Is there anything I may have

info on radio code is here http://www.miata.net/faq/radiosec.html
but I would put money on that NOT being the problem, as the radio would
display CODE or similar.

My cat was playing in the drivers footwell at the time of the click,
but I've checked for any wires he may have pulled out and nothing.

Are you sure the cat didn't pull out and swap any wires or fuses?

Before I make a probably expensive trip my friendly Mazda service man, can
anyone help? The southern motorway is getting a bit dreary and I've

exhausted my

humming repetoire.

I wouldn't go to a dealer, for the money you would spend, you could probably
buy a new stereo. They'd probably just order you a new one anyway. I would
(in this order - and stop if any one of these fixes the problem...)

1. disconnect the radio at the back connector
2. test there is Ground, +ve at the accessory circuit, and +ve at the
continuous circuit with a multimeter/voltmeter on this connector.
3. remove the radio entirely, power it up on the bench (I can help you if
you like) and see if it works.
4. Then open the cover and check for resettable/replaceable fuses, or any
obvious circuit damage
5. Then buy a new one (second hand from the MX5 club web site, or buy a new
aftermarket one) and replace it yourself.

In the mean time, I've found that humming '99 bottles of beer on the wall'
can last for hours if you start from a high enough number.

cheers
H.

PS - Jeff Anderson in the US may have more answers, I can give you an email
address if you like, but I would try these procedures first. I also have a
pulled apart Panasonic stereo somewhere at home, so I will have a quick look
for fuses etc.