Rec counter. Defective.

[Nightwatch]

After many years of it working, it's decided not to. 

May I ask the question where is the feed for this. Is it of the alternator? Or somewhere else. I've had a fiddle to no avail.

 

[WotEver]

Rev counter?

W terminal on the alternator feeds it. Check the multipin plug on the engine first. If that seems okay then check for a voltage on the Rev counter input - it’ll usually read over 7V (it’s a pulsed waveform so won’t read 12V). If you read the voltage then it’s a fair bet that the Rev counter has indeed died. I had to replace one on WotEver. 

[mrsmelly]

11 minutes ago, Nightwatch said:

After many years of it working, it's decided not to. 

May I ask the question where is the feed for this. Is it of the alternator? Or somewhere else. I've had a fiddle to no avail.

 

What engine? The Isuzu ones ALL fail at some time, some seem to last ages but one day...................that's the hours recording counter or do you mean REV counter?

[WotEver]

1 minute ago, mrsmelly said:

What engine? The Isuzu ones ALL fail at some time, some seem to last ages but one day...................that's the hours recording counter or do you mean REV counter?

Clue: C is next to V on a keyboard

[mrsmelly]

5 minutes ago, WotEver said:

Clue: C is next to V on a keyboard

Oh yeah..............it is innitt.................

[Nightwatch]

5 minutes ago, mrsmelly said:

What engine? The Isuzu ones ALL fail at some time, some seem to last ages but one day...................that's the hours recording counter or do you mean REV counter?

REV counter. Barras Shire. 

Another question. I have two alternators, A big one and a not so big one. Big one above the not so big one. Which one will have the W terminal? 

[WotEver]

4 minutes ago, Nightwatch said:

REV counter. Barras Shire. 

Another question. I have two alternators, A big one and a not so big one. Big one above the not so big one. Which one will have the W terminal? 

The one with the wire connected to the Rev counter...

[Nightwatch]

Dead giveaway eh! Can you tell I'm not electrically trained? I shall have a look in a mo or two.

[zenataomm]

X is also next to C on the keyboard, which is why when I went up the Ashby my counter only showed one.

[Tony Brooks]

You may well find the other alternator also has a W terminal. If so it might be quicker to jury connect the revcounter wire to the other alternator and see if it works. IF yes then you almost certainly have a faulty alternator (diode failed). If no then its the wiring, the revconter, or a failure of the 12V +  or - at the revcounter.

I would expect the wire to be on the engine alternator and they are often not monitored so once the instruments come out stick a voltmeter across the engine battery and rev the engine. If the voltage dopes not rise then the alternator has failed (probably brushes). That test will not identify  a failed diode because the alternator will still charge but at reduced current.

[alan_fincher]

39 minutes ago, Tony Brooks said:

You may well find the other alternator also has a W terminal. If so it might be quicker to jury connect the revcounter wire to the other alternator and see if it works.

In which case it's probably worth pointing out that if both alternators have a "W" terminal and you swap to the other one, and the rev counter then springs back to life, it may not actually be giving the right reading, (if it was before).  The rev counter will be calibrated for a particular set up, to include number of poles and (particularly) pulley size.  Unless all attributes of both alternators are identical, it is unlikely that if it read the correct RPM on one that it will then still do so on the other, without recalibration.

[Flyboy]

1 hour ago, Nightwatch said:

REV counter. Barras Shire. 

Another question. I have two alternators, A big one and a not so big one. Big one above the not so big one. Which one will have the W terminal? 

It will be the smaller one on a Barrus.  The black/blue wire.

[Nightwatch]

It's numpty time folks.

Rev counter/tachometer still not working. However, I suspect the smaller of my two alternators is not working as it should. I have noticed recently the engine has not been starting as lively as it does normally. I have a Victron battery monitor and the starter battery, aux, is only showing as 12.30. After engine running for nearly two hours it only reads 12.37. I think the alternator is the problem.

i have a multimeter. Sadly I'm not sure how to use it to test the alternator. To what setting do I turn the dial to, and where do I probe my probes. I apologise for being a bit slow on the uptake. Any 'patient' advice is gratefully accepted. 

[mrsmelly]

Turn it left to the 20 if ya stuffs 12 volt and if the alternator is working it should waz up to somewhere over 14 volts with engine running if mines owt to go by. There may  be a much better way to do it but as u say if its down at 12.3 either the battery is stuffed or the alter thingy is stuffed. Red probe onto positive batt terminal black on tuther end but it doesn't matter it will just read minus if you putt em on ttut wrong ends in reality.

Edited January 24, 2018 by mrsmelly

[Nightwatch]

Thanks Tim. I can never remember where to turn the dial. No reading from any battery 12v or AA. So I now have either a duff multimeter of duff batteries,which is more likely. I normally have a good supply of batteries. I only have one AAA battery. Sod's law strikes again.

Shopping tomorrow it is then. What a sad fellow I am.

[Flyboy]

Is your engine alternator warning light working ? If the bulb has blown the alternator may not be exciting. 

[Tony Brooks]

37 minutes ago, Nightwatch said:

Thanks Tim. I can never remember where to turn the dial. No reading from any battery 12v or AA. So I now have either a duff multimeter of duff batteries,which is more likely. I normally have a good supply of batteries. I only have one AAA battery. Sod's law strikes again.

Shopping tomorrow it is then. What a sad fellow I am.

When you turn the knob to 20v DC does the display start displaying. If not then the battery in the meter probably needs changing.

If it does display you MIGHT have a broken probe wire or a loose connection into the meter.

On 20v DC the meter should show some sort of display even with no cables in it.

[Señor Chris]

58 minutes ago, Nightwatch said:

So I now have either a duff multimeter of duff batteries

Or a duff multimeter fuse. Test it with a meter.

 

[WotEver]

4 minutes ago, Señor Chris said:

Or a duff multimeter fuse. Test it with a meter.

There’s a hole in my bucket, dear Liza, dear Liza...

[Tony Brooks]

10 minutes ago, Señor Chris said:

Or a duff multimeter fuse. Test it with a meter.

 

I doubt the voltmeter part is fused, its usually just the ammeter part - says he who has had countless such meters apart because students will insist on connecting the ammeter up like a voltmeter.

 

When do we point to the cycle computer to rev counter topic?

[philjw]

38 minutes ago, Tony Brooks said:

If not then the battery in the meter probably needs changing.

Check the size. A lot are the 9v volt ones which you see in smoke detectors. I still think of these as PP3 but they're not called that anymore.

[mrsmelly]

6 minutes ago, philjw said:

Check the size. A lot are the 9v volt ones which you see in smoke detectors. I still think of these as PP3 but they're not called that anymore.

Yep me too. pp3........u2..........etc etc

[philjw]

11 minutes ago, mrsmelly said:

Yep me too

I bet you put your tongue on the PP3 electrodes to test the charge too.

[mrsmelly]

7 minutes ago, philjw said:

I bet you put your tongue on the PP3 electrodes to test the charge too.

Yep u got it orrible metallic taste tingle wasn't it!!

[philjw]

1 minute ago, mrsmelly said:

Yep u got it orrible metallic taste tingle wasn't it!!