Is there a test I can do to check my tacho in my gauge set. Wiring to it is ok but with engine running the tacho needle does not move.
Aqua
Testing a factory tacho
Started by
_AquaSLR5000_
, Mar 28 2009 01:48 PM
18 replies to this topic
#2
Rockoz
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Posted 28 March 2009 - 01:53 PM
Post a photo of the circuit board.
Its common for a part to fall off rendering them inoperative.
Its common for a part to fall off rendering them inoperative.
#3
_AquaSLR5000_
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Posted 28 March 2009 - 03:43 PM
Post a photo of the circuit board.
Its common for a part to fall off rendering them inoperative.
I can't post a pic, but I pulled the tacho from the rest of the gauge set and evertything looks ok. The transducer has not broke off and I do get a reading with my multimeter from it. I wired it direct to -ve of coil and direct to negative of battery, fired the car and the tacho still does not work?
#4
Rockoz
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Posted 28 March 2009 - 05:34 PM
i think it should be from neg side of coil to pos side of battery
#5
_AquaSLR5000_
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Posted 29 March 2009 - 03:11 PM
When you look at the back of the gauges you have the brown wire from the -ve side of coil and a black wire which is looped to most other parts of the gauges and is tied to ground. Can someone confirm this
Edited by AquaSLR5000, 29 March 2009 - 03:12 PM.
#6
VitcLJ
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Posted 29 March 2009 - 04:22 PM
there should also be a +ve supply (usually a red wire) from the ignition. without it the tacho will not work.
#7
_AquaSLR5000_
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Posted 29 March 2009 - 04:33 PM
This is a factory tacho and does not have a red wire. Brown from coil and black from gauge loom wiring. Nothing else
#8
Rockoz
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Posted 29 March 2009 - 06:56 PM
Put multi meter leads across the wires that go direct to the meter itself.
Mine has a red wire from the PC Board to the meter, which connects to the board behind 6500rpm.
The other wire is white, and connects to the top spade terminal via the board.
Resistance should be around 140 ohms.
Check the face of the tacho. You should get needle deflection.
If the needles goes down, reverse your multimeter leads.
The deflection will vary dependant on the voltage of your multimeter.
If you get no deflection, then the meter section has lost its smoke somehow.
If the meter moves, then something on the PCB has lost its smoke.
Bits on the PCB only hold very small bits of smoke and its easily lost.
Mine has a red wire from the PC Board to the meter, which connects to the board behind 6500rpm.
The other wire is white, and connects to the top spade terminal via the board.
Resistance should be around 140 ohms.
Check the face of the tacho. You should get needle deflection.
If the needles goes down, reverse your multimeter leads.
The deflection will vary dependant on the voltage of your multimeter.
If you get no deflection, then the meter section has lost its smoke somehow.
If the meter moves, then something on the PCB has lost its smoke.
Bits on the PCB only hold very small bits of smoke and its easily lost.
#9
_AquaSLR5000_
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Posted 29 March 2009 - 07:36 PM
Ok, I got 180ohm reading between the said wires, did not gat any needle deflection regardless of which lead went where - Bugger. Can I apply a voltage to these points to see if the needle moves.
Aqua
Aqua
Edited by AquaSLR5000, 29 March 2009 - 07:40 PM.
#10
Rockoz
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Posted 29 March 2009 - 07:55 PM
By using the multimeter you applied voltage.
If you have a soldering iron desolder the red lead from the board to isolate the meter from the electronics and measure again.
I got about 260 ohms.
I have a feeling your movement lost its smoke.
If you have a soldering iron desolder the red lead from the board to isolate the meter from the electronics and measure again.
I got about 260 ohms.
I have a feeling your movement lost its smoke.
#12
Rockoz
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Posted 29 March 2009 - 09:13 PM
Did you get needle deflection?
#13
_AquaSLR5000_
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Posted 29 March 2009 - 09:34 PM
bugger, did not check for needle deflection. Will have another go tomorrow!
#14
Rockoz
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Posted 30 March 2009 - 04:49 AM
Will be away for a few days.
No deflection will mean bad meter movement.
Other than that it will probably be the board.
The pot or the switch may have bad connections.
Moving these may help, but moving the pot will mean a re calibration.
That wont be too hard to do.
No deflection will mean bad meter movement.
Other than that it will probably be the board.
The pot or the switch may have bad connections.
Moving these may help, but moving the pot will mean a re calibration.
That wont be too hard to do.
#15
_Courage_
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Posted 30 March 2009 - 12:50 PM
Guys i followed all of this but "deflection" what does this mean?
#16
_The Baron_
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Posted 30 March 2009 - 01:55 PM
The needle will twitch/move a little/lots
#17
_AquaSLR5000_
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Posted 30 March 2009 - 06:43 PM
I took the Tacho to a gauge repair bloke in Geelong today. He rigged up his test unit to it and the needle moved after he gave it a nugde. It was sticky when in the zero position and hopefully after he cleans it all it will bo ok.
Thanks for all the help and I will let you know the outcome when I do.
Aqua
Thanks for all the help and I will let you know the outcome when I do.
Aqua
Edited by AquaSLR5000, 30 March 2009 - 06:44 PM.
#18
_AquaSLR5000_
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Posted 01 April 2009 - 07:45 PM
Got my Tacho back today. The repair guy cleaned the actual tacho gauge coil. This stopped it from sticking and I fitted it to the car and is now perfect.
Thanks to Rockoz for all your time and help, much appreciated.
"Gauge Works" in Nth Geelong if you have electrical issues with your cars/bikes
Aqua
Thanks to Rockoz for all your time and help, much appreciated.
"Gauge Works" in Nth Geelong if you have electrical issues with your cars/bikes
Aqua
#19
_torbirdie_
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Posted 01 April 2009 - 09:50 PM
Got my Tacho back today. The repair guy cleaned the actual tacho gauge coil. This stopped it from sticking and I fitted it to the car and is now perfect.
Thanks to Rockoz for all your time and help, much appreciated.
"Gauge Works" in Nth Geelong if you have electrical issues with your cars/bikes
Aqua
whilst you have the tacho working, the following my be useful for others.
The suggested testing with a multimeter on the resistance scale would be okay with older 'needle' multimeters, however, the more sophisticated current day ones will not allow a sizeable current to flow and seeing any needle deflection on the gauge would be difficult.
A good test device is an unsmoothed/filtered 12V dc power supply from a budget battery charger, it will mimmick the oscillating 12V value seen at the -ve of the coil. The tacho can also be calibrated using this as the freqency of the supply is also known
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