Issues with New Radio in BT7

[APM]

I have installed a new Sony radio/CD/Ipod in my 3000 Mk 1 BT7. The car is positively grounded and I have installed the radio using a voltage inverter using the same connections that were used on the older (late 80s) radio that I removed in working order. The insallation works pretty well but....

1 These modern radios have memories with pre-set stations, since I've hooked it up through the ingnition, I lose all the pre-sets and clock time each time I turn the car off. I suppose I could run a dedicated line from the battery to the voltage inverter, bypassing the cutoff switch, however I'm concerned that this may drain the battery. I can live with losing the pre-sets etc but any suggestions would be welcome.

2 The more annoying issue is that the radio seems to switch off/stop working sometimes, particularly when I step on the break (but not always). It does start back up again on the same station and still remembers the pre-set stations, so it's not as if the power has been lost to a degree that would lose the pre-sets. I've checked all the connections which seem good and the wires don't run close to the brake peddle. The radio is well grounded and I've put a voltmeter across the terminals which shows good voltage, but it does seem to dip momentarily on occassion. One thing I thought of is that I have a rubber cover on the accelerator but not the brake peddle. Any ideas what's going on?

Many thanks for any help you can give, Andrew

 

[GregW]

Hi Andrew,
If you use the cut-off switch in the trunk, a bypass wire is about your only solution. If you don't, you could run a wire from the brown wire (always hot) on the ignition switch to the mem input on the radio.

Depending on how much power the radio is drawing, there is a possibility that you are maxing out the generator when you add the brake lights into the mix. I'd guess this happens when the RPM is lower since you've taken your foot off the accelerator, thus generator output would be reduced.

 

[APM]

Thanks Greg, that makes sense, although I'm a little surprized that the radio and brake lights are maxing out the generator, I hope I'm not doing any damage with this setup. Thanks, Andrew

 

[glemon]

The other Greg is right, I have tried the voltage inverter on a couple of Lucas electric cars and had the same cut out issue, especially when applying the brake lights--BT7 is mechanical tach right? if so the conversion to negative ground is very simple-the inverter may draw down current as well if you have it hooked up to the battery direct, I always hook my radio direct to the battery (off the fused circuit to the horn works, brown wire I beleive)

 

[APM]

Thanks Greg. Yes, the tach is mechanical. Unfortunately, I recently had a fairly expensive new fuel pump put in which I beleive means that I can't do the negative ground conversion. So if I hook the voltage converter to the horn that may solve my first problem with the pre-sets, however it might well drain the battery - is that right? Did you find a solution to the cut out issue other than converting to negative ground? Many thanks for the help, Andrew

 

[GregW]

Hi Andrew,
The current draw from the radio memory should be minimal. If you are worried about draining the battery over time, you might want to get a battery tender. The tender will also remind you to turn off the cut-out switch. If you run a bypass wire for the radio and forget the cut-out switch is on, you'll melt the bybass wire when you try to start the car.

What type of fuel pump did you get? I believe the SU pumps that Moss sell have conversion boards that allow you to change polarity for less money than getting another pump.

 

[Ed_K]

For the long term, you would be better off converting to neg. ground. I think your car has a mechanical tach so it is a piece of cake to convert to neg ground. As Greg has said, most of the newer replacement fuel pumps can be used with either polarity. In your car, the fuel pump would be the only possible item that would have to be addressed but it would not be that difficult to modify if it were in fact a polarity sensitive pump.
... I am not familiar with these polarity swapping devices as you are using. In a negative ground car, I would echo what Greg said about connecting a wire from an "always on " wire of your car to the memory lead of your radio....
But you don't have a negative ground car so if you connect a wire to the + memory ( keep alive ) " of your Sony, it may let the Lucas smoke escape from your new Sony !
... For anyone with a modern radio installed, you need to connect a wire from an " always on " wire on your car to the memory keep alive of your new radio so you won't loose the station and setting presets. I installed an ATO fuse holder around my battery cutoff switch and installed the smallest amp self resetting fuse/circut breaker that was available. I think it was either 8 or 10 amps. When the battery cutoff switch is turned off, everything still has voltage in the car including the memory of your radio. If someone tries to start the car with the battery cutoff switch turned off, you hear some buzzing but the starter doesn't even try to engage and you won't loose your station presets. The longest I have ever gone without starting up my car was two months with the memory keep alive attached on my car. I had no problem starting it right up. Those radios do not draw very much current in the memory keep alive circuit. Use a battery tender if you don't start your car all winter. Your battery life will probably be a lot longer. My jet ski battery would only last two years before I bought a battery tender. I am still on the same jet ski battery since I started using a battery tender, ( at least 4 years ), all winter.
Don't be afraid to change over to negative ground. You will be glad you did and never look back.

 

[APM]

Thanks guys. I don't actually know which veriety of replacement fuel pump the garqage fitted, I will ask them. If I change to negative ground is that going to solve my radio cut out issue or am I still going to be maxing out the generator/alternator output? Many thanks, Andrew

 

[GregW]

If I change to negative ground is that going to solve my radio cut out issue or am I still going to be maxing out the generator/alternator output?

That would be a big maybe. It depends on the current draw of the inverter and radio. Another option would be to switch to LED brakelights, but they are polarity sensitive too. They do draw a lot less than the original bulbs though. So that might work with a polarity change on the original generator. So many options, and you just wanted to listen to the radio.

 

[APM]

You got it right GregW - I snuck out in the Healey between doing leaf duty this afternoon - I didn't even think of the radio but just enjoyed the great Healey note. I do like the LED suggestion, I'm not at all familiar with LED, you say they are polarity sensitive, can I get positive ground LED? Many thanks, A

 

[Michael Oritt]

If I change to negative ground is that going to solve my radio cut out issue or am I still going to be maxing out the generator/alternator output? Many thanks, Andrew

------------------------------
I don't think your problem is maxing out the generator so much as the consistency of the voltage and nature of the wave being supplied to the radio. Nevertheless if you switch to negative ground you should definitely go for an alternator.

 

[GregW]

you say they are polarity sensitive, can I get positive ground LED? Many thanks, A

Hi Andrew,
I did a little digging and the only available positive ground LEDs I found were for 6 volt systems. They didn't look like they were particularly bright either. I'd think it would have to be a modification of an existing neg. ground bulb to work and isolate it from the car body. So maybe more trouble than it's worth.

 

[healeynut]

There are people that sell Positive Ground tail lights. That being said, I believe most are of the variety that put out very low levels of light and aren't all that safe:

https://www.norbsa02.freeuk.com/goffyleds.htm

You want a CREE, Luxeon or other 1157 bulb that draws at least 1 watt or more of power. Your typical dome shaped LED will not put out that much power and I would not recommend putting on your car.

Seems to me the problem is your connections are corroded, causing resistance in the circuits somewhere, which is causing your problem.

Either your brake light connections are corroded, your radio line, or even the connections on your charging circuit.

I would go through the process of disconnecting and reconnecting every bullet, screw or blade connector in each of these circuits and see if that solves your problem.

Good Luck!

:thumbsup:

 

[glemon]

I don't know what radio you are using, but I have tried an inverter/radio in a couple cars (not healeys, but same lucas generator and voltage regulator unit) and had the same cut out issues, switched to negative ground and it went away and radio worked great.

If you like originality the grounding switch is less noticeble than the inverter box.

 

[APM]

A lot of good info here. I hope Healeynut's right about corroded connections - I'll definitely check that. Micahel, I was wondering if it might be a slightly wobbly voltage inverter, I guess I can check that by seeing if I get steady voltage across the terminals before engaging the inverter. I see a weekend under the dashboard in my future. I like the idea of the LED lights and appreciate the link. Many thanks to all for the ideas, Andrew