Lotus Elan

Need Help with Tach signal.

PostPost by: tvacc » Tue Jul 07, 2015 3:29 am

Hi all.

Have a 1966 Elan here. Positive ground. Just had the Tach rebuilt at Nisonger.

Put it back in car and it is still not working. I am missing something. It is wired properly as far as voltage. 12 volts positive to ground and 12 volts negative to power.

I must have the sensor wrong. White wire comes from the coil. From the negative post. Then goes to the ignition switch just like it is supposed to. Here are some pictures. I need help on this. Open to ideas on what I have done wrong or what I am missing.
Attachments
P1040340.jpg and
P1040338.jpg and
P1040337.jpg and
P1040334.jpg and
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PostPost by: lotusfan » Tue Jul 07, 2015 8:12 am

Tony

It looks to me like you have assembled it wrongly. The 'U' shaped metal clip forms part of a transformer core and the coil of wire should go through it. What you need to do is to index you plastic block with the white wire through 90 degrees so that the coil of wire is inside the metal clip.

Clear??
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PostPost by: Craven » Tue Jul 07, 2015 10:25 am

Hi
Yes the metal bridge should fit in the groove on the block, you have it presently at 90 deg to where it fits.
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PostPost by: billwill » Tue Jul 07, 2015 11:30 am

lotusfan wrote:Tony

It looks to me like you have assembled it wrongly. The 'U' shaped metal clip forms part of a transformer core and the coil of wire should go through it. What you need to do is to index you plastic block with the white wire through 90 degrees so that the coil of wire is inside the metal clip.

Clear??


I'm not sure it is a transformer as such. But it is indeed at 90 degrees to its correct position.

It forms a conducting LOOP of metal, which in turn passes through the transformer which is inside the case. AS such there must be good cantact between the bridge piece (that the white wire is wound around) and the two fingers of metal which you can just see in the picture. If necessary clean the contacting sufaces.

On second thoughts, ignore the tiny text above.

It is indeed a transformer, the bridging metal piece and the two tongues sticking out of the back of the tachometer are of magnetic material and form a magnetic loop. The white wire (en-route to the ignition coil) wound around the bridge piece forms the primary of the transformer and the secondary can be seen in the following photo as a coil of fine wire covered by a yellow plastic sleeve.

TachoSignalInput.jpg and
Smiths Tachometer Signal input (RVI type)
Last edited by billwill on Tue Jul 07, 2015 12:15 pm, edited 1 time in total.
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PostPost by: tvacc » Tue Jul 07, 2015 11:45 am

When I bought the car, the previous owner had it this way and the tach was not working. So I sent it out. Probably was ok. Can someone take a picture of how it is supposed to look like? A picture is worth it all on this case. I have not seem one of these set up right since my last S2 which is. almost 50 years ago.
Tony Vaccaro
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71 Spyder Elan, ElanGTS, 93 Caterham, 05 Elise,
99 Elise190, 91 M100 Elan, 74 Europa, 72 Europa JPS #15, 68 Elan Coupe RHD
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PostPost by: tvacc » Tue Jul 07, 2015 11:55 am

OR if someone can point me to an illustration in some book. I probably have all the books.
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99 Elise190, 91 M100 Elan, 74 Europa, 72 Europa JPS #15, 68 Elan Coupe RHD
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PostPost by: billwill » Tue Jul 07, 2015 12:20 pm

This image from the photo library shows how it should be:

Image

See the discussion in this topic:
lotus-electrical-f38/tachometer-reading-too-high-europa-t21763.html
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