VDO tach hookup help please.

[Casper4104]

VDO tach hookup help please.

One of the good guys here was kind enough to send me a used vdo tach.  I think it's a VDO 333533 - it looks exactly like this one:

http://shop.torresen.com/ships_store/index.php?p=details&mfc=VDO&sku=333533

There was a paper sticker on the bottom of the gage with hookup instructions, but it got wet and i can't make it out.

It's a potentiometer type, no dip switches.  There are 4 blade terminals on the back.

From left to right:


+ (plus sign)

Letter "S" over a number "1"

downward arrow (ground)

Letter "S" next to downward arrow (ground)



There is also a socket in the back to stick a little light into, I know what to do with that.  I assume that once I get the thing hooked up, I borrow a handheld tach from work and use the potentiometer to calibrate the thing.  What I don't know is how to hook it up.

Help please - what hooks to what?  I think I know what to do with the + (12 volt from the batt?) and the ground seems pretty straightforward, but what is S1? (one of the lugs on the gen? which one?) S ground? (huh?) I searched the archives and struck out.



Thanks in advance - chipping away.

Casper4104

(Oh yeah, installing is a 1958 Gm PD4104 with the 6-71 and the old generator the size of a Hyundai.  You guys'll need to know that huh,,,)

[Dallas]

Casper, the SiemensVDO website has the installation instuctions in PDF format that you can download.

http://www.siemensvdo.com/home

That might be the easiest way for you to get the correct instructions.

IHTH

Dallas

[Casper4104]

Hey Dallas,

That's the first place I looked and I got my buttkicked.  Maybe it's there, but in a solid hour of poking around I didn't find it.

Thanks for trying - I think I'll go poke around some more.

Casper

[Dallas]

Casper,

Try this:

http://www.siemensvdo.com/downloads/marine-solutions/




IHTH

[Casper4104]

Yep, that's where I ended up.  Only 1 tach on the page:

http://www.siemensvdo.com/NR/rdonlyres/EDFE8A89-6F4D-4B52-BA52-765746AA8880/0/Installation_Instructions_Tachometer_Drehzahlmesser.pdf

Not like mine, has dip switch. Still looking,

Thanks,

Casper

[ChuckMC8]

Casper, I beleive that you need a signal from a magnetic pickup for that tach. Thats exactly the setup mine has on the back. You may have a threaded hole on the bellhousing that is directly over the flywheel teeth....I had to make one. You screw the sensor into the hole until it contacts the flywheel, then back off 1/2 turn. It works great. If you need to drill a hole, the sender uses pipe thread that about 9/16" diameter. I determined the correct spot on the bell housing and used a 5/8" drill to make the hole. Then, I went to Lowes and bought a black pipe nipple the right size and checked the threads and all was cool. (So I didnt have to thread the bellhousing, Ijut "welded on" the threads) Next, I took a hacksaw and cut the nipple into, so that I had a threaded part about 1/2" tall. I placed my threaded part over the said hole in the bellhousing and tacked it on with my mig welder, screwed in the sender and I said above, and hooked up the 2 signal wires and ran them to the front, hooked up the tach and viola! Dere she goes.
    its easier of course, if you have a threaded port already on the bellhousing. My MC8 had one on the very bottom of the bellhousing. I installed the sender there 1st, connected it with the tach in my hand, Then, I started the engine and made sure that it worked before I went to much more trouble. I didnt want to block that lower hole, figuring that it was a necessary drain, but on my fire truck engine, it has a plug in that hole from the factory, so go figure.
   One caveat, however, My tach has an adjustment screw on the back. I thing to be completely accurate, you need a handheld tach and check the pulley on the cam gear (same RPM as the crank) to properly set the RPM. I beleive that mine idles at 550 to 600, so that was my initial setting. I'll work on borowing a hand held unit to make sure.
  The planning on the sender mount took a while to figure out, but reall only took about 15 miutes to do-
On your tach, "S" is the signal, the other "S" or "S1" is the return, the sender has two wires, thats where they go (about 20 gauge) you can hook them up either way and its OK. The "+" is 12 Volts in and of course, "G" is da ground.
The magnetic sensor senses the flwheel teeth and generates a small pulse current..the tach counts and displays the result.
hope this helps, chuck