Hi,
Last year I bought a Eunos 93 MK1 1.8
The radio was dead. I visually checked the fuses, and they looked ok, I tried my best to follow the wiring diagram, but it’s not very clear. I re-checked the fuses, but by continuity this time, and found 2x fuses, that look ok, were corroded through, so the were open circuit.
Now replaced, the antenna goes up and down, the Cd slot accepts a cd, the display shows frequency, very faintly, and there’s noise for the speakers, which gets louder, if I turn the volume. The is no signal, so no music. The radio is an od Sony, complete with compact disc player, so it’s pretty old, and the wiring has been adapted to work it, but the original sockets are still there.
I don’t want to spend too much time on it, and am quite prepared to buy another.
What is the best way to go please?
Cheers, Camerart
Sounds like you know what what you want to do but want some confirmation it’s the best thing.
Well, I for one agree that buying something that works is the best thing 
Depends where you live. I’ve got an old working Pioneer single din cd radio that you can have for £10 plus postage,.
there are usually loads for that sort of price on Gumtree, sphock etc.
Halfrauds had new ones c£20 recently too
First I would plug in another aerial directly in the back of the radio (any old bit of wire a couple of metres long into the middle of the socket would do for a test), it could be that the mast or any of the several contacts along the way or even the lead itself are damaged or corroded.
Also, did you actually try playing a CD?
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Hi M,
I live in Dorset, and I make take you up on your offer, although it may add up to the Halfords price with the postage.
C.
Hi M,
Your aerial test is a good idea, which I’ll try.
I did try the cd, but I couldn’t hear any spinning noises, or music.
Thanks C.
Hi M,
Thanks for the link, I’ll get one if the existing one proves no good.
C
Hi R,
With a wire plugged in, I got stations
I don’t think the CD works, also there is a compact disc player, which lights up, but of course I don’t have any. No matter.
I’m not sure how the lead connects to the aerial, as it’s a bit cramped. I tried a continuity test from the outside of the lead, to GND and it showed K Ohms.
Cheers, C.
Good. At least the radio is working. And you know the mech accepts and ejects the CD so some of CD and the controls work.
CD often has a dirt problem on the laser system, can sometimes be cured with a cleaning CD. At worst take the lid off and clean the lenses very, very gently with brake cleaner and cotton bud or tissue. Don’t dismantle any of the CD mech.
The aerial end should be earthed to the bodywork securely, sometimes (depending on year) there is even an extra wire to a grounding tag. If there is no connection on the outer from one end to the other then it is ether broken or unplugged (but mast goes up and down so likely OK). There is normally a plug into or near the aerial, and another behind the trim by the driver’s right knee as well as the one into the back of the head unit.
The fact the aerial goes up and down means the power lead from the head unit and ground are connected somewhere, so all that is left is the signal wire and the connection to the mast itself. Test this by tagging that test aerial wire onto the inner at the plug at the aerial end of the body wire.
See the manuals on Mellens for connections and where they are located, (US oriented, but most of it is the same except for mirroring around the dash etc.) Top level index is here in the link below, and it is worth looking at the Extra Manuals as well.
http://www.mellens.net/mazda/index.html
The specific year manuals below might not have what you need, so look around the other years as well, most of it is much the same.
http://www.mellens.net/mazda/Mazda-Miata-1991-1993/index.html
http://www.mellens.net/mazda/Mazda-Miata-1991-1993/1991_wiring.pdf
http://www.mellens.net/mazda/Mazda-Miata-1991-1993/electrical_component_locations.pdf
Hi R,
Thanks for the links to manuals. I have a manual, plus I’ve been searching for other wiring information. Much of it is not as clear as I would have liked.
To clarify, when you say “head unit” do you mean the aerial itself? If so then I have disconnected it also at the radio end, and there’s not continuity of the inner or outer of the coax, assuming it is coax. (I’m reluctant to cut the insulation, just yet)
Does the coax go under the car, or is it inside, under the carpet etc? I’ve yet to find the ‘by the drivers right knee’ connection ( I assume you mean left knee in the UK?)
If I can’t find it, can I buy the coax plus both ends, so I can make one up and route it myself?
NOTE: To clarify, the aerial goes up/down without the coax being connected
C
Head unit is the Sony. Aerial is the mast going up and down. The coax will be going along the right inside of the car, under the carpet not sure if under the seat or beside the seat and comes up by your UK right knee. Usually there is a connector near where the dash ends and the side trim down to the floor begins, or somewhere around there maybe a bit lower, however I expect this one is OK.
The most likely failure points are:
the wire is broken inside the plug going into the radio (at the crimp or solder),
or in the plug going into the aerial (same again),
or connecting to the mast itself (corrosion in a couple of places inside the mast unit).
Which is why I suggested trying something other than the mast at the mast end of the wiring.
It is a process of elimination:
start at either end seeing where good or not,
divide in two and check again,
and again in the relevant direction,
work in ever smaller chunks towards the fault.
Good luck and have fun. It is a learning experience, and think of the triumph when you have it working again!
Hi R,
Got it!
I know the coax is broken somewhere, and my usual test is to stick a needle into the wire, bearing in mind the outer and inner, so that I can work along it, and do as little damage as poss.
No wonder I couldn’t find it near my left knee I’ll check the other side tomorrow.
Once fixed, if the aerial doesn’t work I’ll try a wire again. I realise that with the radio on, and the coax ok, then any wire touching the centre would make a noise on the radio.
Can’t fail now 
Thanks for all of your input.
C.
On a ‘93, I’m pretty sure that the antenna cable runs under the carpet along the centre console.
Hi RR,
Ok, thanks. and a nice day for wire searching.
I did note that, following the wire from the aerial into the 'cockpit, it was biased towards the middle, which seems to verify what you say.
C.
Hi R,
Correct, the inner wire at the radio plug. Once shortened and re-soldered, the radio now works.
Thanks for your and others help.
The radio display is very low, but can just about be seen. I’m not too worried, as it has a search and memories, that I have worked out, and this is not my main vehicle, just a bit of fun. Hence the reluctance to buy a new radio, as suggested.
I’ve changed some of the important bits on the car, like some break bits, underseal, and cam belt.
Cheers, C. EDIT: There are speakers in the seats!
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