VDO Tach Hookup ?

[Dreamscape]

OK guys here's the deal. I've done a search on the subject, checked the siemens/vdo website and I have some questions.

I have a VDO Tach, 4,000 rpm ( I know Dallas  ), it has a potentiometer, no dip switches, one terminal W/S1, other is ground, ( I got that one figured out ). Their website does explain to some degree how to hook it up. I assume that I hook a wire to the "R" terminal on my 50 DN and the other to the W/S1 terminal. My question is this, is a sender used? I could not find any information on that. What size wire is used? Do I need to hook up a diode? I have a 12 volt system.

I'll also secure a photo tach to set it up, Dallas did teach me something!

Just want to make sure all my ducks are in a row and not scattered!

Please be gentle, 

~Paul~

[JackConrad]

OK guys here's the deal. I've done a search on the subject, checked the siemens/vdo website and I have some questions.
I have a VDO Tach, 4,000 rpm ( I know Dallas  ), it has a potentiometer, no dip switches, one terminal W/S1, other is ground, ( I got that one figured out ). Their website does explain to some degree how to hook it up. I assume that I hook a wire to the "R" terminal on my 50 DN and the other to the W/S1 terminal. My question is this, is a sender used? I could not find any information on that. What size wire is used? Do I need to hook up a diode?
I'll also secure a photo tach to set it up, Dallas did teach me something!
Just want to make sure all my ducks are in a row and not scattered!
Please be gentle, 
~Paul~

Paul,
  We have a Datcon 3000 RPM tach on our bus that is connected to the R terminal of our alternator.  When we installed the new 24 volt air cooled, belt driven "truck type" alternator, I had to re-calibrate the tach (different drive ratio). The wire from the R terminal on our  alternator goes directly to the S terminal on the tach (no diodes). My Datcon tach requires a small ( I think 5/32") allen wrench to adjust the potentiometer.  My old gear driven alternator was a 12 pole (6 pulses per revolution) with a final ration of 2.77:1. The new alternator was also 12 pole with a final drive ration of 2:1. It took very little change in the potentiometer to adjust.  I was told by the tech at Precision Speed Instruments to adjust at full RPM for a more accurate setting.  our tach is not VDO,but I hope this will help.  Jack
PS: on the back of our tach, there is also a small knob that can be set to 4, 6, or 8. Ours was set at 4.

[RTS/Daytona]

 For  -MOST-  Detroit Diesel Delco gear driven 50DN  270 Amp 24 volt alternators "R" Terminal hookup

<>         The "R" terminal output is 12 volt -
<>         Most 6V92 / 8V92-->(2.94 (53/18) gears & 6 pulses per rev=17.66 pulses/rev)
<>         Most 24 volt - 8v71->(2.75 (55/20) gears & 6 pulses per rev=16.5  pulses/rev)
<>         Most 12 volt - 8V71>(2.29 (55/24) gears & 6 pulses per rev=13.75 pulses/rev)           
         
     Note A  ->For you engineers - I used a 12  volt A/C transformer with an unfiltered full
                  wave rectifier to test - 60 cycles via a full wave bridge=120 pules/sec
                  17.66 p/rev (D/D Delco 270 ALT) - adj for 408 RPMs
                  12.00 p/rev (Computerized DDEC) - adj for 600 RPMs
     Note B ->For other Unique applications (Pulses/rev)
                  see (www.dakotadigital.com) DSL-1 $65) + others

[Dallas]

Paul,

Check your mail,

I sent you 5 PDF files with the set up instructions.

I think the first one is for yours.

Dallas

[Dreamscape]

Thanks Dallas, I'll check them out!

~Paul~

[Mrbill4108]

Dallas,

Can't you post them here for all to see? 
That way if someone else needs them they can find them.

Mrbill4108

[Dallas]

I would but the files are too large to post here.

If anyone else wants them, just holler, I'll be glad to email them.

Dallas,

Can't you post them here for all to see? 
That way if someone else needs them they can find them.

Mrbill4108

[Dreamscape]

Dallas, All the files show what I think is a later model with a display, I do not have that feature. It does give me enough information to get me by though. I'm thinking I'll hook it up to the alternator for now then get a pulse generator or whatever I need to hook it up the the blower crank or ?





Thanks for the help Dallas and RTS/Daytona!

~Paul~

[Dallas]

Paul,

If you can find a part number on it, I'll look through my olde files and see what I have for it.

[Dreamscape]

Here is what the sticker on the side says, 1 211 160 010 A, Pierce Manf., 12 volt 0176.

[Dallas]

I'll check tomorrow Paul, I think I may have that one

[David Anderson]

Paul, I wish you luck.  I had the same problem hooking up my VDO tach (3000 rpm)  I never could get it to work correctly off the alternator.  I have a Niehoff 350amp.  It is hard to talk to a VDO tech guy that knows what to tell you.  At their recommendation I finally bought a sender and screwed it into the bottome of my flyweel.  There was a 1/2 or 3/4 hole there that you can see the teeth on the flywheel.

VDO had to know how many teeth it had to set the dip switches.  I marked one tooth with white out and pried the flywheel with a screwdriver 360 degress and counted the teeth.  With that, VDO gave me the proper setting.

Now, you wrote you have no dip switches.  How do you calibrate? 

David

[Dreamscape]

David, The only way that I know of is a screw in the back that I'm assuming is a potentiometer of some sort, it has an arrow that starts small and increases in size.

If I can't get a good reading, I'll probably hook it up the way you did or off the blower.

Are having fun yet?

~Paul~

[Dallas]

Paul,

I came up with these two diagrams, from some website a long time ago.

Hopefully, one will work for you.

Dallas

[Dallas]

By the way, I just remembered, I have a tach sensor from the flywheel setup on an 8V92/HT740 if it would help.
You'll need to drill a hole in the bell housing and tap it with a bottoming tap because the clearance between the bell housing and the fly wheel is very close.
If you are lucky, the hole is already there and tapped.

Dallas