alan
Well-Known Member
The "strip" with numbers on is just the joint(s) (plug/socket) in the wiring loom between the engine and the control panel.
Alan.
Alan.
Rev Counter failed - how to test for failure point?
- Thread starter Richard10002
- Start date
Andrew_Fanner
Well-Known Member
Do you know that the counter itself is still good? If the engine output is AC rather than pulses it could be a blown bridge rectifier, 26p from Maplins.
Mal113
Well-Known Member
Richard.
Your comment "Quote It's failure coincided with removing the sensing lead from the alternator and extending it to sense at the domestic battery Unquote" This would appear to be incorrect, on most alternators there is a terminal that is marked for sensing alternator pulses that are used for the RMP meter, this is an AC pulse (frequency). The faster the engine rotates the higher the frequncy, this frequency is converted by the RPM meter to read the correct RMP, you may have seen that some RPM meters have an adjustment knob, with numbers i.e. 1, 2, 3, 4 this changes the bias on the internal electronic circuit so the same RPM meter can be used with different alternators and pulley ratio's.
Now if you have moved this connection the the battery terminal I assume you are supplying a DC signal to the RPM? If so it will not work, reconnect the instrument to the alternator sensor terminal.
Your comment "Quote It's failure coincided with removing the sensing lead from the alternator and extending it to sense at the domestic battery Unquote" This would appear to be incorrect, on most alternators there is a terminal that is marked for sensing alternator pulses that are used for the RMP meter, this is an AC pulse (frequency). The faster the engine rotates the higher the frequncy, this frequency is converted by the RPM meter to read the correct RMP, you may have seen that some RPM meters have an adjustment knob, with numbers i.e. 1, 2, 3, 4 this changes the bias on the internal electronic circuit so the same RPM meter can be used with different alternators and pulley ratio's.
Now if you have moved this connection the the battery terminal I assume you are supplying a DC signal to the RPM? If so it will not work, reconnect the instrument to the alternator sensor terminal.
Richard10002
Well-Known Member
[ QUOTE ]
Richard.
Your comment "Quote It's failure coincided with removing the sensing lead from the alternator and extending it to sense at the domestic battery Unquote"
Now if you have moved this connection the the battery terminal I assume you are supplying a DC signal to the RPM? If so it will not work, reconnect the instrument to the alternator sensor terminal.
[/ QUOTE ]
It was the battery sensing lead that I moved, not the Rev Counter sensing lead... although I can see how what I posted could be misinterpreted.
I didnt disturb the Rev Counter lead... which is what is frustrating!
Richard.
Your comment "Quote It's failure coincided with removing the sensing lead from the alternator and extending it to sense at the domestic battery Unquote"
Now if you have moved this connection the the battery terminal I assume you are supplying a DC signal to the RPM? If so it will not work, reconnect the instrument to the alternator sensor terminal.
[/ QUOTE ]
It was the battery sensing lead that I moved, not the Rev Counter sensing lead... although I can see how what I posted could be misinterpreted.
I didnt disturb the Rev Counter lead... which is what is frustrating!
Richard10002
Well-Known Member
[ QUOTE ]
Do you know that the counter itself is still good? If the engine output is AC rather than pulses it could be a blown bridge rectifier, 26p from Maplins.
[/ QUOTE ]
Do you mean the Tachometer as a whole, or the engine hours counter?
I dont know if the Tachometer is good, and one of the things that would be handy would be a test to see if it is.... e.g. could I feed it with 240V A.C. to see if it registers anything
DONT WORRY - I'm sure I cant do the above but, if it is fed with AC from the Alternator, it must be possible to feed it with an AC current of some kind from some other source.. so I'm wondering what kind of AC, (Volts and Hz), and what kind of source could provide that.
Hope that makes sense.
Richard
Do you know that the counter itself is still good? If the engine output is AC rather than pulses it could be a blown bridge rectifier, 26p from Maplins.
[/ QUOTE ]
Do you mean the Tachometer as a whole, or the engine hours counter?
I dont know if the Tachometer is good, and one of the things that would be handy would be a test to see if it is.... e.g. could I feed it with 240V A.C. to see if it registers anything
DONT WORRY - I'm sure I cant do the above but, if it is fed with AC from the Alternator, it must be possible to feed it with an AC current of some kind from some other source.. so I'm wondering what kind of AC, (Volts and Hz), and what kind of source could provide that.
Hope that makes sense.
Richard
kaysveistrup
Member
Don't know if this may help but similar probs with Vauxhalls. If the alternator stops working or charging you lose the engine rev counter. so it goes to say that either the alternator is knackered, not charging or the sensor for detecting the charge rate is not positioned properly. Run motor and check voltage at batts, should be 14.2 v. If not its an alternator problem. If approx 14.2v then look to sensor. Good luck