Georgia Dubs
Would you like to react to this message? Create an account in a few clicks or log in to continue.

Tach testing

3 posters

Go down

Tach testing Empty Tach testing

Post by Gabass Tue Feb 11, 2014 9:17 pm

I need some help with testing this electric VDO jet gauge tachometer. It is set up for 6 or 12 volt. It has a terminal for positive (1), negative (-), 6v (+6), and 12v (+12). Not sure how to bench test this, what wires go where. Some electrical guidance would be appreciated. Thanks
Tach testing IMG_2407_zpsfe420621
Tach testing IMG_2416_zps9b66fd80
Tach testing IMG_2414_zpsf384dedf
Tach testing IMG_2415_zps41f7ac6c
Gabass
Gabass
Dub Nut

Number of posts : 350
Age : 26
Location : Watkinsville, GA
Registration date : 2013-01-17

https://www.facebook.com/NorthGeorgiaSpeedometer?fref=ts

Back to top Go down

Tach testing Empty Re: Tach testing

Post by pwmcguire Tue Feb 11, 2014 10:21 pm

I think bench testing would be difficult. The way I see it  you would either put 6 (+6) or 12 (+12) volt positive in their respective locations, only one, whatever you are using. (-) would be negative either 6 or 12 whatever you are using. (1) would be a negative input from the coil of the vehicle, where the points connect to on the coil. It is also labeled (1) on the coil. Positive is labeled (15). (Look at the wiring diagrams on the samba, all years). You would have to test it on a car. The negative from the coil pulses on and off when the points open and close. That is how it determines the RPM along with the selector switch for 2, 4, 6, 8,. That would be set to how many cylinders there are on the engine.


Last edited by pwmcguire on Tue Feb 11, 2014 10:31 pm; edited 1 time in total
pwmcguire
pwmcguire
Complete Dub Addict

Number of posts : 787
Age : 56
Location : Kennesaw
Registration date : 2009-08-06

Back to top Go down

Tach testing Empty Re: Tach testing

Post by Gabass Tue Feb 11, 2014 10:28 pm

Thanks, I'll see what I can do.
Gabass
Gabass
Dub Nut

Number of posts : 350
Age : 26
Location : Watkinsville, GA
Registration date : 2013-01-17

https://www.facebook.com/NorthGeorgiaSpeedometer?fref=ts

Back to top Go down

Tach testing Empty Re: Tach testing

Post by Attack chicken Wed Feb 12, 2014 12:23 pm

If you have a battery charger you can test it/calibrate it without another vehicle/tach. Here is a link, go a little past half way down to the test section. The charger should make a tach set up for 4 cylinders read 3600 rpm. This works great, I've done it several times with converted factory techs and is very accurate.

http://grannys.tripod.com/rx7tachrecal.html

Attack chicken
Dub Nut

Number of posts : 104
Location : Hiram
Registration date : 2013-02-13

Back to top Go down

Tach testing Empty Re: Tach testing

Post by pwmcguire Wed Feb 12, 2014 12:55 pm

I'm not understanding how you would connect a battery and a charger to Wilson's tach.
pwmcguire
pwmcguire
Complete Dub Addict

Number of posts : 787
Age : 56
Location : Kennesaw
Registration date : 2009-08-06

Back to top Go down

Tach testing Empty Re: Tach testing

Post by Attack chicken Wed Feb 12, 2014 1:17 pm

The battery would go to the positive and negative terminals, the battery charger is used as a signal source.

Clip of the above link

PREFERRED SIGNAL SOURCE...an inexpensive 12v battery charger can be used as a deadly accurate signal source for the re-cal of your tach. This signal source is so steady and accurate that there is no need to compare the reading with another V-8 calibrated tach. Battery chargers typically use a rectifier bridge to convert the AC power source into DC. This turns the 60 hertz sine wave input into a 120 hertz ripple wave DC output. The ripple wave output is be read as 3600rpm by the stock rotary calibrated RX-7 tach. For a V-6 application, an RX-7 tach should be adjusted to read this signal as 2400rpm. For a V-8 application, adjust your RX-7 tach to read this ripple signal as 1800rpm. Please note that you must use a 12v battery for a power source, and the battery charger as a signal source only. The ground wires for both the battery and the battery charger should be connected to the ground terminal of the tach.


Attack chicken
Dub Nut

Number of posts : 104
Location : Hiram
Registration date : 2013-02-13

Back to top Go down

Tach testing Empty Re: Tach testing

Post by Sponsored content


Sponsored content


Back to top Go down

Back to top

- Similar topics

 
Permissions in this forum:
You cannot reply to topics in this forum