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Triumph TR6 - convert tach to electronic

Has anyone converted their old mechanical tach to electronic possibly by taking the guts out of a modern electronic tach VDO Autometer? I have a tach converted by Revington that worked great for about a year and just died. All that seems to be in it is a small circuit board which I have no hope of fixing. I don't really want to send it back to England cost would be in range of $150 plus shipping. Any ideas.
Richard Porter

Richard, I ran across these guys when searching for electronic tach conversion sources as I have been thinking about going the that route myself. Don't know anything about them except what you will find from their web pages. If you wind up using one of these guys, please let us know how it goes.

Does it have the "orignal workings" in place, and if so it can be Fixed in Melbourne Australia for about 85 Australian dollars. My tacho stopped working a month or so again, and I took to a Tacho/Speedo shop not far from home and it was back in two days, and it works like a bueaty.
KG Farley

I did just what you discribed with my tach.
I bought a an electronic tach at the auto store and removed the housing and face plate, did the same to the original tach and attached the original face plate to the electronic tachs guts then wired it up according to the directions with the new tach.
Simple, works very well.
Christopher Trace

I sent an e-mail to Revington and apparently the circuit board is available for about $50.00. I may go that route because I think it is just a simple pull old and put in new I hope. Cheaper than guts of new put in my old tach. I really like the rock steady needle of the old tach when working.
Dick Porter

dumb question # 1000

when you convert to the electronic tach, what is the signal thats srives it?

Bob Craske

can't find my tach instructions at the moment but from memory the new tach picks up signal from the coil.
Christopher Trace

The tach does pick up signals from the coil and I was doing research yesterday and found an article on the web and it notes that you need to find a tach with the same degree in sweep as the stock. Has anyone found this to be not true?

Don, I just bought what ever was there and it works fine. However, because I picked up a fairly cheap unit
the accuracy is out by a couple of hundred RPM at high revs. I found this out when I had the car dynoed 4-5
years ago, but revs up to 4000 were accurate to with in
25 RPM which is fine for my use.
I have to admit that I'm not sure what "degree of sweep" refers to, can you explain?
Christopher Trace

Chris- might be easier to read than explain.

"The reader should study the gauge in need of service. Measure and record the needle’s degree of angular “sweep” over theface and the maximum reading on the gauge face. One of the most common Smiths/Jaeger tachometer configurations has a range of 7000 RPM with approximately 270o sweep of the needle. The reader should seek a suitable, voltage sensing, donor
tachometer having the same range and sweep. If the reader cannot obtain a donor tachometer that matches the sweep and range of the Smiths unit, they should find a donor with MORE sweep for the same maximum RPM (i.e. 7000 RPM with 280o sweep). Alternatively, seek a donor with the same degrees of sweep but with a slightly lower maximum RPM (i.e. 6000 RPM with 270o sweep). Donor tachometers can usually be found at the same sources listed in the previous paragraph. The donor tachometer may be either a “sealed” unit from a manufacturer such as Smiths, VDO, AutoMeter, Sun, etc., OR in some instances part of a later car’s dash IF the tachometer is not driven by the donor car’s computer. (Unsuitable donor tachometers will NOT have a tachometer circuit board attached, they will only have the needle movement with connection."

Well I got the new circuit board from Revington and was pretty easy to install. Pegged the needle the first time but there is an adjustment and now my old rock steady tach is back. This time however the needle seems to not react to engine speed near as fast as the prior board. Who knows why.
Dick Porter

This thread was discussed between 16/03/2006 and 27/03/2006

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