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MG Midget and Sprite Technical - CAR RADIO TESTING.

Hi all, I have 2 old car radios in my workshop, I would like to test them to see if any of them are working. How could I do this without blowing something. I have a spare 12v battery. I want to try and do it without putting them into my midget.
Padrig.
P Jeremiah

wire them correctly and use a fuse
Mick - trying to sort the wiring

Thanks Mick, now surprise surprise, how do I know if I'm wiring them correctly? is there a standard colour code?
Padrig
P Jeremiah

The main issue is: are they + or - earth radios?

60's or before likely to be +ve; later ones will be -ve earth. If you get this wrong, you will destroy many of the semi-conductors in them, and unless you're competent with the soldering iron they will be scrap.

There should be an external indication of which polarity they are.

I don't think there's a standard wiring code - and even 'professionals' can get it wrong, ie. around 5 years ago my son took a CD-player from one of my cars to install in his own; the idiot at Halfords who sold a conversion kit and was assigned to fit it assumed brown wire was earth (when for that player is was +ve supply) and that was the end of it; he said of course the player was faulty, despite being removed from my car in working condition.

Then you have the issue of speaker connections; for old radios, there's normally only one speaker so connection should be obvious... maybe you can test using an old speaker.

A
Anthony Cutler

speakers.....
get a speaker, it will have a pos, and neg. side, look on the radio it will have a pos. and a neg. speaker wire, hook up pos to pos and neg to neg.

antenea...
get car antena and look for a big cable on the back of the radio that looks like the antena cable

Powering the radio
look for the pos. and neg. power wires on the radio, hook up a 12v inline fuse on the pos. powwer wire, then hook the neg. wire to the neg barrty side, and the positive with the 12v inline fuse onto the pos. side of the radio.

turn on radio, tune into good 80 hairband station, pump up the volume and head bang cause "You got a right----To PARTY!!!!

As to the inline fuse, not really needed, if the radio is going to blow the fuse, and the radio is set up correctly, then the radio is thrash, but with an inline fuse you can keep it alive long enough to get 5 dollars at a pawn shop

Also on the back of the radio there will be 2 sets of "Channels"aka 2 speakers or 4 channels aka 4 speaker set up, for testing it dosnt matter, which speaker channel as long as its a pos. neg. from the same speaker channel

prop
Prop

Mmmm i didnt think of the positive earth ...good point. Here in the states, something like that is ither really old and rare, (Im 44 and only seen 1 in my life time) or extremely brand new...who knows what auto enginerrs are doing to cars these days

most of the time there is a wiring scematic glued and yellowed to the casing somewhere

Prop
Prop

Padrig -- post a photo it may help!
Mick - trying to sort the wiring

This thread was discussed on 02/05/2009

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