Duckpit Posted June 8, 2017 Share Posted June 8, 2017 I have had my Smiths rev counter repaired by John Ostick, but unfortunately it works for about 10 seconds and then goes to zero. John was adamant that the repair was OK & suggested I go direct to the coil and connect up. But the problem persists.As I know how good John is I thought I would give it a try on my Alpine V before I went back to John and of course it worked perfectly.!!The dizzy has electronics from Simonbcc onboard as does the Alpine I think..Any ideas appreciated?Nick Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted June 8, 2017 Member Share Posted June 8, 2017 How strange. When you connected it directly to the coil were you using the existing power and earth or did you rig something new? Have you tried wiggling bits to restore function? The engine runs normally as that 10s expires? Do you have a multimeter?JonathanPS: Alpine V as in Sunbeam? Link to comment Share on other sites More sharing options...
Duckpit Posted June 9, 2017 Author Share Posted June 9, 2017 Hi JonathanWhen connecting direct to the coil I did not use any of the current wiring, so wiring is not my problem. My next step is to put a diode in line to prevent any bouncing pulses and I may even try a resistor these items cost pennies, then I guess change the coil and finally the electronic gizmo.Yes I have a Sunbeam as my dry day normal use car, it rattles a bit but much nicer than than a modern tin topNick Link to comment Share on other sites More sharing options...
Duckpit Posted June 13, 2017 Author Share Posted June 13, 2017 I have found the problem but do not know how to sort it.When I disconnect the dynamo the rev counter works fine ??Any ideas Nick Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted June 13, 2017 Member Share Posted June 13, 2017 Well done. Is it really a dynamo and does it have a separate voltage regulator?And do you have a multimeter?Jonathan Link to comment Share on other sites More sharing options...
Duckpit Posted June 13, 2017 Author Share Posted June 13, 2017 Oh yes, a dynamo with a separate voltage regulator, but I dont know how to sort the problem. One suggestion is that the voltage at the battery is too high, so am off to borrow a multimeter.If it is too high, can I adjust at the regulator ?Nick Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted June 13, 2017 Member Share Posted June 13, 2017 We don't know what the cause is yet, especially as it recurred with that direct connection. But today's discovery is going to help a lot in diagnosis.Do you have a wiring a diagram that matches the car?Is it positive or negative earth?Jonathan Link to comment Share on other sites More sharing options...
revilla Posted June 13, 2017 Share Posted June 13, 2017 It would be interesting if John Ostick could tell you what the actual trigger condition is for the rev counter, then get an oscilloscope on the signal voltage being fed to it. For (a completely made up as i don't know the actuals, but it illustrates the point) example if it counts the number of times the voltage crosses upwards through 5V in a given time, and your signal voltage is swinging 4.5V to 10V, it will work fine but be a bit marginal; if a 1V increase in battery voltage then had it swinging 5.5V to 11V it would then read zero as the voltage would no longer pass through the 5V trigger level. A friend recently had a similar issue and it was a simple matter of adding a pull-up or pull-down resistor (costing pennies) to match the gauge to the signal. The problem may be gathering the data; if you managed to get a scope trace of the tacho signal you are getting, John would probably be able to tell you if the gauge should be able to work with that or if not, what it would take to match them properly. Link to comment Share on other sites More sharing options...
Duckpit Posted June 13, 2017 Author Share Posted June 13, 2017 OK so I have over 16V at the battery, and when I discharge the battery the rev counter works for longer. I think that there are too many volts.Fortunately there is a good video on Youtube which shows how to adjust the voltage so I will give that a try.Unfortunately John hasn't exactly been helpful, my last response from him was just a load of ??????????????????????? Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted June 13, 2017 Member Share Posted June 13, 2017 Fortunately there is a good video on Youtube which shows how to adjust the voltage so I will give that a try.That's what I'd do next.Jonathan Link to comment Share on other sites More sharing options...
revilla Posted June 13, 2017 Share Posted June 13, 2017 16V does sound a little - enthusiastic! Let us know hoq you get on. Link to comment Share on other sites More sharing options...
Duckpit Posted June 13, 2017 Author Share Posted June 13, 2017 Sorted.The voltage actually went up to 17.5V before adjusting. When adjusting down came the volts and up went the revs.I had to buy a new voltage regulator when I was restoring the Lotus and now find out that these are not plug and play like modern devices but need calibrating. I guess I am lucky that I didn't burn out any other electronics.Nick Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted June 13, 2017 Member Share Posted June 13, 2017 Well done.Jonathan Link to comment Share on other sites More sharing options...
revilla Posted June 13, 2017 Share Posted June 13, 2017 Yes well done. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now