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wwwben
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Joined: September 18, 2022
Posts: 28
Location: Upper Peninsula of Michigan
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Dale M.
Samba Member
Joined: April 12, 2006
Posts: 20379
Location: Just a tiny bit west of Yosemite Valley
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 Posted: Mon Sep 26, 2022 7:09 am Post subject: Re: Tachometer not working |
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Did you set both switches to "ON" per instructions?
_________________
“Fear The Government That Wants To Take Your Guns" - Thomas Jefferson.
"Kellison Sand Piper Roadster" For Street & Show.
"Joe Pody Sandrover" Buggy with 2180 for Autocross (Sold)
============================================================
All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ... |
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wwwben
Samba Member
Joined: September 18, 2022
Posts: 28
Location: Upper Peninsula of Michigan
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| Posted: Mon Sep 26, 2022 7:11 am Post subject: Re: Tachometer not working |
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| Dale M. wrote: |
| Did you set both switches to "ON" per instructions? |
Yep sure did ..and When ignition is on i see the needle move slightly to the 0 position .. but it doesn't move after that |
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wwwben
Samba Member
Joined: September 18, 2022
Posts: 28
Location: Upper Peninsula of Michigan
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| Posted: Mon Sep 26, 2022 8:46 am Post subject: Re: Tachometer not working |
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If it helps .. I thought I would mention that there was never a tach installed on this unit
and there is another wire coming from the negative terminal that goes to a metal barrel looking thing attached to the outside of the distributor. |
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Wulfthang
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Joined: August 25, 2018
Posts: 719
Location: Tucson
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| Posted: Mon Sep 26, 2022 10:20 am Post subject: Re: Tachometer not working |
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The metal barrel thing attached to the distributor is the condenser. You're running points, right? The negative terminal on the coil is the one that runs to the distributor. Correct?
Most tachs will have three wires. Ground, Positive and Signal. Signal is the one that runs to the Coil Negative.
Because the needle goes to Zero, I think the problem is probably with the Signal wire. |
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wwwben
Samba Member
Joined: September 18, 2022
Posts: 28
Location: Upper Peninsula of Michigan
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| Posted: Mon Sep 26, 2022 11:05 am Post subject: Re: Tachometer not working |
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| Wulfthang wrote: |
The metal barrel thing attached to the distributor is the condenser. You're running points, right? The negative terminal on the coil is the one that runs to the distributor. Correct?
Most tachs will have three wires. Ground, Positive and Signal. Signal is the one that runs to the Coil Negative.
Because the needle goes to Zero, I think the problem is probably with the Signal wire. |
I am completely new to this sort of thing so I have no idea about "points"
but yes, there is a green wire running from the negative side of the coil, to the condenser on the distributor.
I have check the wire many times and I have continuity all the way from that connector on the coil to the end of the wire inside the tach..
I will snap a photo when I get home ..since I would like some help identifying which engine I have anyway |
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Wulfthang
Samba Member
Joined: August 25, 2018
Posts: 719
Location: Tucson
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| Posted: Mon Sep 26, 2022 3:09 pm Post subject: Re: Tachometer not working |
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| wwwben wrote: |
| Wulfthang wrote: |
The metal barrel thing attached to the distributor is the condenser. You're running points, right? The negative terminal on the coil is the one that runs to the distributor. Correct?
Most tachs will have three wires. Ground, Positive and Signal. Signal is the one that runs to the Coil Negative.
Because the needle goes to Zero, I think the problem is probably with the Signal wire. |
I am completely new to this sort of thing so I have no idea about "points"
but yes, there is a green wire running from the negative side of the coil, to the condenser on the distributor.
I have check the wire many times and I have continuity all the way from that connector on the coil to the end of the wire inside the tach..
I will snap a photo when I get home ..since I would like some help identifying which engine I have anyway |
Well, you may not know about points but that you know about and have checked the continuity on the signal wire puts you way ahead of most!
That being the case and since you're sure it has B+ and B-, return the tach for an exchange! If the engine runs and the signal wire is good to the tach and the tach has proper voltage, it has to be the tach. |
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wwwben
Samba Member
Joined: September 18, 2022
Posts: 28
Location: Upper Peninsula of Michigan
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| Posted: Mon Sep 26, 2022 3:46 pm Post subject: Re: Tachometer not working |
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the white wire in the pic above (the one connected to the coil with the green wire)goes to the signal wire of my tach
is this correct? |
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Dale M.
Samba Member
Joined: April 12, 2006
Posts: 20379
Location: Just a tiny bit west of Yosemite Valley
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| Posted: Mon Sep 26, 2022 6:43 pm Post subject: Re: Tachometer not working |
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| wwwben wrote: |
the white wire in the pic above (the one connected to the coil with the green wire)goes to the signal wire of my tach
is this correct? |
Yes....
Two things... Bad splice on white to green wire at tach or bad unit....
_________________
“Fear The Government That Wants To Take Your Guns" - Thomas Jefferson.
"Kellison Sand Piper Roadster" For Street & Show.
"Joe Pody Sandrover" Buggy with 2180 for Autocross (Sold)
============================================================
All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ... |
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Wulfthang
Samba Member
Joined: August 25, 2018
Posts: 719
Location: Tucson
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| Posted: Mon Sep 26, 2022 7:03 pm Post subject: Re: Tachometer not working |
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Here's how to test if it's a bad tach......if you have a volt meter. Substitute the volt meter for the tach with the setting on at least sixty volts DC. Positive is the signal wire, chassi is ground. Start with the highest setting on the meter in DC and reduce it as needed. (With the engine running) At some setting, the volt meter will duplicate a tach and swing with the rpms.
'Course, you won't know what the rpms are because most meters aren't scaled for rpms unless it's an automotive type meter or a really good industrial grade multi-meter. Regardless, it tells you that all systems are go for launch EXCEPT for the tach unit itself! That's really what it sounds like. |
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wwwben
Samba Member
Joined: September 18, 2022
Posts: 28
Location: Upper Peninsula of Michigan
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| Posted: Tue Sep 27, 2022 3:24 am Post subject: Re: Tachometer not working |
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| Wulfthang wrote: |
Here's how to test if it's a bad tach......if you have a volt meter. Substitute the volt meter for the tach with the setting on at least sixty volts DC. Positive is the signal wire, chassi is ground. Start with the highest setting on the meter in DC and reduce it as needed. (With the engine running) At some setting, the volt meter will duplicate a tach and swing with the rpms.
'Course, you won't know what the rpms are because most meters aren't scaled for rpms unless it's an automotive type meter or a really good industrial grade multi-meter. Regardless, it tells you that all systems are go for launch EXCEPT for the tach unit itself! That's really what it sounds like. |
I did this and here is the result....
(digital meter
hooked up the way explained above the meter zeros out
engine running the meter goes crazy showing all kind of numbers in the MV range
revving engine makes numbers increase but never reaches a single Volt only stays in the MV range
SO THEN I decided to hook it up at the coil
and i got 10V idle and it goes up when revving
Must be my signal or ground wire .. even tho they test fine .. I am using a fairly thick wire for it and the ground is not dedicated (im sharing one ground for a few items)
I will run a separate signal and ground tonight and see how that goes |
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wwwben
Samba Member
Joined: September 18, 2022
Posts: 28
Location: Upper Peninsula of Michigan
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| Posted: Tue Sep 27, 2022 4:55 am Post subject: Re: Tachometer not working |
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Update ... it was driving me crazy so I decided to dig into it a little more ..
thanks to you guys for the help IT WORKS NOW 
what should I set my max RPM for? |
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Dale M.
Samba Member
Joined: April 12, 2006
Posts: 20379
Location: Just a tiny bit west of Yosemite Valley
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| Posted: Tue Sep 27, 2022 6:55 am Post subject: Re: Tachometer not working |
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What did you do to make it work?...
What size engine do you have... The engine "build" will determine what the max RPM you can safety push it to...
_________________
“Fear The Government That Wants To Take Your Guns" - Thomas Jefferson.
"Kellison Sand Piper Roadster" For Street & Show.
"Joe Pody Sandrover" Buggy with 2180 for Autocross (Sold)
============================================================
All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ... |
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Wulfthang
Samba Member
Joined: August 25, 2018
Posts: 719
Location: Tucson
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| Posted: Tue Sep 27, 2022 8:09 am Post subject: Re: Tachometer not working |
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Yeah, I should have specified to use a needle type meter. Digital meters are to sensitive and pick up all kinds of extraneous electrical noise when used like that. Sorry!
Good that it's working now. What was wrong? |
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wwwben
Samba Member
Joined: September 18, 2022
Posts: 28
Location: Upper Peninsula of Michigan
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| Posted: Tue Sep 27, 2022 8:41 am Post subject: Re: Tachometer not working |
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| Dale M. wrote: |
What did you do to make it work?...
What size engine do you have... The engine "build" will determine what the max RPM you can safety push it to... |
I have no idea why .. but just re-running new wires made it work .. Maybe a wire got damaged ..
And I have no idea what size engine I have .. is there any way to find out? |
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Mal evolent
Samba Member
Joined: March 31, 2009
Posts: 2912
Location: San Antonio, Nuevo Mexico
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| Posted: Tue Sep 27, 2022 10:25 am Post subject: Re: Tachometer not working |
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| Quote: |
| I have no idea about "points" |
points are a mechanical switch, connected between the negative side of the coil, and ground. when the points are closed current flows through the primary side of the coil. current flowing through a wire creates a magnetic field. this primary coil is relatively few turns of large wire. it is designed for battery voltage and high current
When the points open, the current stops flowing and the magnetic field collapses inward. that collapsing magnetic field is a magnetic field in motion. when a magnetic field moves past a wire, a current is induced in that wire. there is a secondary coil. this collapsing magnetic field induces current into the secondary coil. the secondary coil is many turns of fine wire.
the magnetic field generated by the low voltage high current primary coil becomes a high voltage low current field in the secondary coil. this is a function of the ratio of the number of turns in each coil. this is where the spark at the plug comes from
the voltage created in the primary coil by the collapsing magnetic field is vastly higher than the voltage that created it, and of opposite polarity. my 6 volt motorcycle generates a negative 321 volt spike when the points open. the condenser snubs but does not eliminate the spark at the points. this is why points end up pitted.
repeating the most important point, for emphasis: the spark at the plug occurs when the points OPEN. the vast reverse polarity spike that occurs when the current tries to flow backwards through the opening points is what triggers the tach.
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wwwben
Samba Member
Joined: September 18, 2022
Posts: 28
Location: Upper Peninsula of Michigan
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| Posted: Wed Sep 28, 2022 11:46 am Post subject: Re: Tachometer not working |
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| Mal evolent wrote: |
| Quote: |
| I have no idea about "points" |
points are a mechanical switch, connected between the negative side of the coil, and ground. when the points are closed current flows through the primary side of the coil. current flowing through a wire creates a magnetic field. this primary coil is relatively few turns of large wire. it is designed for battery voltage and high current
When the points open, the current stops flowing and the magnetic field collapses inward. that collapsing magnetic field is a magnetic field in motion. when a magnetic field moves past a wire, a current is induced in that wire. there is a secondary coil. this collapsing magnetic field induces current into the secondary coil. the secondary coil is many turns of fine wire.
the magnetic field generated by the low voltage high current primary coil becomes a high voltage low current field in the secondary coil. this is a function of the ratio of the number of turns in each coil. this is where the spark at the plug comes from
the voltage created in the primary coil by the collapsing magnetic field is vastly higher than the voltage that created it, and of opposite polarity. my 6 volt motorcycle generates a negative 321 volt spike when the points open. the condenser snubs but does not eliminate the spark at the points. this is why points end up pitted.
repeating the most important point, for emphasis: the spark at the plug occurs when the points OPEN. the vast reverse polarity spike that occurs when the current tries to flow backwards through the opening points is what triggers the tach. |
I keep reading this over and over hoping it will sink in .. such a complex item ..
So the coil kind of acts like a step up transformer? |
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Dale M.
Samba Member
Joined: April 12, 2006
Posts: 20379
Location: Just a tiny bit west of Yosemite Valley
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| Posted: Wed Sep 28, 2022 1:06 pm Post subject: Re: Tachometer not working |
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| wwwben wrote: |
| Mal evolent wrote: |
| Quote: |
| I have no idea about "points" |
points are a mechanical switch, connected between the negative side of the coil, and ground. when the points are closed current flows through the primary side of the coil. current flowing through a wire creates a magnetic field. this primary coil is relatively few turns of large wire. it is designed for battery voltage and high current
When the points open, the current stops flowing and the magnetic field collapses inward. that collapsing magnetic field is a magnetic field in motion. when a magnetic field moves past a wire, a current is induced in that wire. there is a secondary coil. this collapsing magnetic field induces current into the secondary coil. the secondary coil is many turns of fine wire.
the magnetic field generated by the low voltage high current primary coil becomes a high voltage low current field in the secondary coil. this is a function of the ratio of the number of turns in each coil. this is where the spark at the plug comes from
the voltage created in the primary coil by the collapsing magnetic field is vastly higher than the voltage that created it, and of opposite polarity. my 6 volt motorcycle generates a negative 321 volt spike when the points open. the condenser snubs but does not eliminate the spark at the points. this is why points end up pitted.
repeating the most important point, for emphasis: the spark at the plug occurs when the points OPEN. the vast reverse polarity spike that occurs when the current tries to flow backwards through the opening points is what triggers the tach. |
I keep reading this over and over hoping it will sink in .. such a complex item ..
So the coil kind of acts like a step up transformer?
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Simply...YES...
_________________
“Fear The Government That Wants To Take Your Guns" - Thomas Jefferson.
"Kellison Sand Piper Roadster" For Street & Show.
"Joe Pody Sandrover" Buggy with 2180 for Autocross (Sold)
============================================================
All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ... |
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wwwben
Samba Member
Joined: September 18, 2022
Posts: 28
Location: Upper Peninsula of Michigan
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| Posted: Wed Oct 05, 2022 7:58 am Post subject: Re: Tachometer not working |
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| So i took it out for a drive today and it seems like it wants to shift at like 3 on the tach .. could this be correct? |
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Dale M.
Samba Member
Joined: April 12, 2006
Posts: 20379
Location: Just a tiny bit west of Yosemite Valley
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| Posted: Wed Oct 05, 2022 9:42 am Post subject: Re: Tachometer not working |
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| wwwben wrote: |
| So i took it out for a drive today and it seems like it wants to shift at like 3 on the tach .. could this be correct? |
Did your butt tach tell you it was at the top end of its torque curve...
_________________
“Fear The Government That Wants To Take Your Guns" - Thomas Jefferson.
"Kellison Sand Piper Roadster" For Street & Show.
"Joe Pody Sandrover" Buggy with 2180 for Autocross (Sold)
============================================================
All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ... |
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