Drehzahlmesser umpolen??

[MichaelW]

Hallo Leute,

es wird endlich Sommer und nun kommt Onkel Lukas und ärgert mich. Ich werde jetzt wohl mal schnell die Elektrik an meinem 67er Midget neu machen. Den Kabelbaum mache ich mir selbst (wegen den ganzen Änderungen), die Lima wird Wechselstrom. Dabei will ich auch auf "negativ Earth" umstellen.

Jetzt meine Frage:

Wie fröggele ich den Drehzahlmesser um? Die alten DInger sind ja leider auch "Richtungsgebunden beim Strom"

Danke für alle Tipps


Michael

[Andreas]

Michael,
hier ein Auszug aus der Umbauanleitung von John Twist. Ist in der Tat "Fröggelei"!

9) Tachometer. If the car is fitted with a mechanical rev counter, then obviously this section will not apply. The RVI tach is labeled on its face whether it is positive or negative earth. It is driven by a pulse
from the hot side of the coil. Modern tachometers are driven by the pulse from the distributor side of
the coil, and are much improved over the older RVI units. Two changes are necessary to make the tach
work: a) the wires must be reversed at the "white wire loop" at the back of the unit; and b) the power
and earth connections must be reversed on the inside of the unit.
a) The wire in the "white wire loop" comes from the key switch and
travels to the hot side of the coil. Select one of the wires and tag it with two
pieces of tape for identification. Then cut the wire between the pieces of tape,
and cut the other wire to the same length. Reverse the connections (now there
is one piece of tape on each wire), and solder them (remember-- this is the
power lead for the coil and is unfused). Tape up the connections carefully,
When later replacing the plastic block on the back of the tach, ensure that the
metal band around the block is carefully positioned. This is a necessary half
of the electromagnetic pickup.
b) To reverse the power wire and earth wire on the inside of the unit, it is necessary to remove the
chrome ring, the glass face, and the glare shroud. The chrome ring is usually removed with great
difficulty by prying at it with a small screwdriver at the tabs. Then, remove the two screws on the back
of the unit that hold the internals to the case, and allow those internal to drop carefully into your hand.
DON'T BEND THE NEEDLE! The spade terminal which carried the green or white wire is the power
lead. Just next to this is the earth connection. One of the two leads is a resistor. Unsolder the wires and
resistor from their positions and reverse them, resoldering the connections. Reassemble the unit after
cleaning the glass.

[MichaelW]

Hallo Andreas,

das sieht ja wirklich nach gefröggele ohne Ende aus. Trotzdem vielen Dank für die Info!! Ich werde heute mal mit der Elektrik anfangen und mir den DZM demnächst vornehmen.

Thx

Michael