Rev Counter (Tachometer) Resistor or Wiring Diagram

[tonycharente]

Hello All,
Am trying to help a French friend with a problem on his Elan +2 S130/5. His Rev Counter (Tachometer) stopped working following an electrical problem. His garage examined the Rev Counter and found the resistor to have burnt out. [I would have thought there'd be more than one resistor, but I'm just reporting what my friend was told.] The guy was unable to read the colour coding of the burnt out resistor because (you guessed...) it was burnt out. I have tried to find a wiring diagram of the Rev Counter internals, without success.

Please can anyone tell me what the resistance should be, and/or provide such a wiring diagram, please?
Many thanks,
Tony

[Higs]

The following page contains an internal wiring diagram for the rev counter near the bottom (don't be put off by the pages name!):

http://freespace.virgin.net/tommy.sandham/alternator_conversion.htm

You were correct - there is more than one resistor!

Hope this helps

Richard

[tonycharente]

The following page contains an internal wiring diagram for the rev counter near the bottom (don't be put off by the pages name!):

http://freespace.virgin.net/tommy.sandham/alternator_conversion.htm

You were correct - there is more than one resistor!

Hope this helps

Richard

Hello Richard,
And many thanks for your rapid reply. I'm forwarding the diagram "gif" part of the link to my friend!
Thanks again
Tony

[alan71]

There are two types of rev counter, this is the later one.

Alan.

[tonycharente]

There are two types of rev counter, this is the later one.

Alan.

Many thanks Alan,
Have forwarded your attachments to my friend.
Thanks again
Tony

[bob_rich]

Hi

I think the circuit in Alan71 post is not correct. I have attached a link to a page from a book review that features the single transistor RV1 tacho. I would imagine that the burnt out resistor is R1 the 39 ohm as this passes the full meter current . I guess, irrespective of any debate over which circuit is correct, if the 39 ohm resistor is changed it would be put back where it came from so circuit knowledge would not be needed to correct the fault. As an aside if the unit is taken apart I would change the capacitor C1 as this being low ( value tend to go off with age) can make the tacho response very uneven with a tendency to misread when other electrical circuits are operated.

best of luck

Bob

http://books.google.co.uk/books?id=9kQ9 ... &q&f=false

[tonycharente]

Hi

I think the circuit in Alan71 post is not correct. I have attached a link to a page from a book review that features the single transistor RV1 tacho. I would imagine that the burnt out resistor is R1 the 39 ohm as this passes the full meter current . I guess, irrespective of any debate over which circuit is correct, if the 39 ohm resistor is changed it would be put back where it came from so circuit knowledge would not be needed to correct the fault. As an aside if the unit is taken apart I would change the capacitor C1 as this being low ( value tend to go off with age) can make the tacho response very uneven with a tendency to misread when other electrical circuits are operated.

best of luck

Bob

http://books.google.co.uk/books?id=9kQ9 ... &q&f=false

Many thanks Bob,
I've forwarded your reply to my friend too! I expect he's a bit confused by now, but I'm seeing him tomorrow!

Thanks again,
Tony

[alan71]

The diagram is something I found on the internet a while ago and saved , I haven?t checked it.
Looking through some photos I took when I had one apart the 2 resistors seem to be red/red/gold/silver = 2.2 Ohms and orange/white/black/silver = 39 Ohms.

Alan.