TR4/4A Positive ground inverter

[Marla]

I bought a new Retrosound radio for my Tr4 and have spent a few days trying to figure out why it was not getting any power so I looked at other Retrosound radios on ebay and noticed that the main wire harness had a different fuse set up to the one I received in the box...I ordered another fuse harness that matches the ones I saw and that should have come with my radio and after some thinking I remembered the Positive Ground thingy and what I believed happened was when I ordered my radio they sent me a Positive Ground Inverter...I took 2 photos...one on the left is what I should have received and the one on the right is what I got...am I correct???Marla

 

[TR3driver]

Their records would no doubt show the TR4 as being positive ground; so unless you told them otherwise, I would say the one on the right is "correct" for your application.

If your car has been converted to negative ground (which is certainly the way I would go), then I think you want the one on the left.

 

[Marla]

I never said pos or neg...the ad says negative ground only and that is what I ordered...I called the shop that sold it to me and he asked if it was neg ground...but this was a couple of days later...anyway,thank you for answering this question...Marla

 

[sp53]

It sounds like your car is positive ground and it looks to me like the one on the right is some knida something and probably something to reverse polarity. Back in the day when your car was new the radios had a little switch on the back to change from negative to positive ground and would say that right on the switch . So look on the radio back and see if it has that little switch. Perhaps you could post a picture of the radio if it is not installed or either way. One problem with the negative ground stuff on positive cars is the antenna because the antenna is the often the ground for the radio. I run a positive ground tr3 car with a negative ground radio in the glove box and have for many years without an problems and not using an antenna because I usually listen to CDs anyway and it is my understanding an FM radio does not use that old style antenna.

 

[Got_All_4]

I used this for decades in my positive ground TR3. Now that I converted it to negative ground I don't have any use for it. Worked great with a modern radio.

 

[CJD]

The "thingy" on the right harness looks like a choke to me...that would be for ignition noise reduction, and nothing to do with pos/neg ground.

If you hooked a neg ground radio to a pos ground, the unit may be fried?!?

 

[Marla]

https://www.ebay.com/itm/RetroSound...ash=item3f7955869b:g:GEgAAOSwA29Y5CWU&vxp=mtr...


Actually it works now but I am not going to use it due to the bulk of the wiring...It is the Long Beach model and too much stuff ...Secretaudio SST is for me...ow well another $429.00...not spent well...anybody want to buy a "cheap radio" ?...Marla

 

[sp53]

Anyways, I guess that sst means hidden and that is what I am saying I did. I put cheap 75.00 Sony CD player in the glovebox with the speakers under the dash so they cannot be seen and no antenna. The whole parts job cost about 125.00 and works great. Just drilled some holes in the back of the glovebox for the wirers then bought some 1 inch by 1 aluminum right angle for the speaker frames and screw gunned it to the left and right kick panels. Try and get your money back or credit for a CD player and some speakers because they were not giving you good information. Look at what CJD wrote.

 

[Got_All_4]

That's a lot of money to give up on. There are 3 ways to use that radio. The first is what Randal suggested and that is to convert to negative ground. But if keeping it in the period is more important then using the inverter is the next simple solution. Last is you would wire it as intended positive to positive but you would have to totally isolate the radio from touching any ground including the antenna. I did that at first and cut a rubber grommet out of a rubber inner tube to insulate the antenna washer from touching any metal. Problem there is you loose your ground plane so reception becomes an issue. It was also to nerve racking too to keep it that way as I had to always be careful not to touch the radio with live wires. Then someone suggested the inverter to me which I never heard of before.

My next issue too is my radio. Looking at the reproduction radio consoles but not sure that I want that big thing under my dash. I had mounted my radio under the glove box which of course is cardboard with a metal plate inside to help support the cardboard glove box. It totally isolated the radio too. I drove it for 30 years that way.

 

[Marla]

What happened was when I ordered the radio it came automatically as a positive ground where as my car is a negative ground so when it would not work I ordered a neg ground wire plug in from the company...I agree the radio is too much for the space it would occupy so I am going with the Secretaudio SST...the Retrosound I will keep as we are always buying different cars and one day I will place it in another classic...this radio is adaptable for use in all radio openings due to it's knobs ability to shift...it is a great radio so I am not taking a loss...here is a photo of a Retrosound radio I put in our 1970 C10 2 years ago...Marla