Tachometer interference?

[65-440]

I doubt it's a magnet problem. Note how close mine is to the speaker. And I'm using an aftermarket dual speaker with a FM converted radio.

http://[URL][URL]https://garytayman.com/

[/URL][/URL]
If you are working under the dash be sure and do not losen the screw any more than absolutely necessary to slide a forked spade terminal under it.
Small is better.
I was nervous about the screw coming all the way out which should be a nightmare.

Well new gauge from charger specialties, additional ground wire added and zero difference..still pointing at speaker with ignition off!

 

[Sinitro]

Well new gauge from charger specialties, additional ground wire added and zero difference..still pointing at speaker with ignition off!

I posted a few days back..
A suggestion to uninstall the front speaker.
What happens??
This will confirm if in fact the speaker's magnetic field is the issue.
Advise back what happened.

Just my $0.02...

 

[dadsbee]

Don't see a speaker magnet pulling an aluminum needle upright, but they make some amazing supplements these days...

 

[RemCharger]

But more importantly; does the needle still bounce when running..

 

[Speedbird]

Exactly. He may have more than one issue.
If it's the AMS tach it definitely needed a ground per my experience.
What about the other "symptoms". If no improvement there it may be an ignition issue ya'll were talking about on the first page.
Need to know if it's an easy working area.
Is the new tach being bench tested prior to installation?

Tachometer Jumping

Hi all, I have a 68 standard gauge dash with a tachometer. Full electronic MSD ignition setup. Hooked up the tach per MSD instructions. The tach seems like a reproduction (maybe OER). I can spot the green printed circuit board. So it should NOT need a tach adapter at all. Without it shows a...

www.forbbodiesonly.com

 

[65-440]

I posted a few days back..
A suggestion to uninstall the front speaker.
What happens??
This will confirm if in fact the speaker's magnetic field is the issue.
Advise back what happened.

Just my $0.02...

I'm not pulling the speaker, I hooked the tach up under the hood with jumper wires and it stays at 0 with ignition off....it's definitely a magnetic pull, I verified it outside the vehicle with a speaker I had laying around.....The guys over at AMS know about it there's just not a solid solution to shield the speaker magnet.

 

[65-440]

But more importantly; does the needle still bounce when running..

Nope, well maybe a tad but nowhere near as bad as the 1st one. I had another tach in the car before switching to this one and it was steady as can be.

 

[65-440]

Don't see a speaker magnet pulling an aluminum needle upright, but they make some amazing supplements these days...

AMS is well aware of this issue, nothing new apparently. Supposedly it's only an issue with this particular tach model.

 

[65-440]

Exactly. He may have more than one issue.
If it's the AMS tach it definitely needed a ground per my experience.
What about the other "symptoms". If no improvement there it may be an ignition issue ya'll were talking about on the first page.
Need to know if it's an easy working area.
Is the new tach being bench tested prior to installation?

http://[URL]https://www.forbbodiesonly.com/moparforum/threads/tachometer-jumping.285105/

[/URL]

Yes, before I put it in the dash I ran it in the engine compartment. Battery power removed and it sits at zero. Once in the dash is back pointing towards the speaker!

 

[Speedbird]

I'm not clear on what's going on at this point.
As I understand it.
The tach works OK now other than not giving steady indication when the engine is running and the needle points to the radio speaker when turned off.
Wait let me go to the garage and look..........

I think the needle pointing to the radio when off is NOT a problem based on my operating characteristics. Functionality is good, in my case after providing a ground. Maybe that's "normal".
If your needle is shaking during operation after you provided a ground?
Other than a possible ignition signal problem causing an unsteady induction, one difference in our cars COULD be your radio. Note previously that I've had mine updated. Certainly not a problem if the radio isn't even on??

 

[pnora]

Take a strong magnet and pass it across the cluster and see if it reacts to it. That will tell you for sure how sensitive it is. If it reacts to that I would send it back and either find another source for a new one or a source to rebuild an old core.

 

[Speedbird]

Take a strong magnet and pass it across the cluster and see if it reacts to it. That will tell you for sure how sensitive it is. If it reacts to that I would send it back and either find another source for a new one or a source to rebuild an old core.

Heck no. Mine works fine. I'm not screwing around with it. Go first page and see.

 

[pnora]

Heck no. Mine works fine. I'm not screwing around with it. Go first page and see.

My comment was for the poster with the problem. When I hit reply it included your suggestion. I edited my post.

 

[Billccm]

 

[Kern Dog]

I have a Dakota Digital instrument cluster in my car. Two years back I wanted to try an FBO ignition box. When I tried it, the tach needle bounced. I tried soldering in a diode but it made no difference. The Dakota Digital people told me that their tachometers sometimes react this way with some ignition systems so I pulled the FBO stuff back off.

 

[Speedbird]

FBO in this car too. No issue report.

Dakota Digital Gauges

I'm extremely happy with the VHX system we selected for the Charger. There were a number of boxes to check that made this decision for us. While aftermarket gauges may not be right for everyone, in choosing what do about instrumentation for this car our primary concern was future reliability...

www.forbbodiesonly.com

 

[RemCharger]

Battery's been disconnected for 7 months, no speaker magnet. That's why I was wondering who originally made the tach.

 

[65-440]

I'm not clear on what's going on at this point.
As I understand it.
The tach works OK now other than not giving steady indication when the engine is running and the needle points to the radio speaker when turned off.
Wait let me go to the garage and look..........
View attachment 1833433
I think the needle pointing to the radio when off is NOT a problem based on my operating characteristics. Functionality is good, in my case after providing a ground. Maybe that's "normal".
If your needle is shaking during operation after you provided a ground?
Other than a possible ignition signal problem causing an unsteady induction, one difference in our cars COULD be your radio. Note previously that I've had mine updated. Certainly not a problem if the radio isn't even on??

Not sure what's done to your radio, but mine is a factory '68 radio completely gutted and an aurora design bt 2.4 board installed( AM/FM/USB/Bluetooth)
The tach is steady enough with engine running to live with, the 1st one would not stop moving around! It's the needle resting at the 2ish o'clock position with key off that is bothering me.

 

[65-440]

Take a strong magnet and pass it across the cluster and see if it reacts to it. That will tell you for sure how sensitive it is. If it reacts to that I would send it back and either find another source for a new one or a source to rebuild an old core.

I'll do that, although when the tach is hooked up in the engine bay the needle rests at zero with power removed