Centrodyne 610 and 620 Internal Jumpers -Fred Stock, owner Fred Stock Electronics, www.TaxiCabElectronics.com

Inside Centrodyne Taximeters in the 600 Series, there is a set of pins which determine how the vehicle speed signal
is related to the meter. When installing your meter, you will need to set the jumpers on a small field of gold pins
located on one of two circuit boards inside the meter. There are six pins, found at the upper left corner of the back
board. Remove the slotted silver screw at the lower right corner of the face of the meter,
and remove the seal-cover.
On the Silent 610 meter, the little door is silver. On the Silent 620 printing meter, the door is black, and slides out
to the right after the bolt is removed. Then remove two Phillips-head screws at the back of the meter, releasing the
case and the mechanism. Slide the face and meter front out of the metal case.

C610 Pins
Inside you will find two circuit boards. We are interested in the back board - the one with the large square IC chip in a square socket. At the corner which was at the upper left when the meter was assembled, find six gold pins about a centimeter long. There are two small plastic cased jumpers, which, when placed over two pins, electrically short the pins The jumpers always cover the middle pin, and either the inner pin or the outer one in each row of three.

Centrodyne generally ships their meters with the jumpers set for FORD motors, that is, with the center pin and the
inner pin covered with the jumper cap in each row. The two caps are ALWAYS side by side, NEVER offset with one
in and one out.

Manufacturers of Vehicles determine what type of Vehicle Speed Sender they will use. In Ford products, the VSS is analogue. That means the signal can pass from zero to a high point, then back to zero, then to a low point and finally back to zero. This implies the signal can have either negative or positive polarity at any given moment. To set your meter to be used with a Ford Co. product, place the jumpers from the center pin in each three pin row, to the inner pin, the one furthest from the edge of the circuit board. General Motors and Chrysler generally have 610 Jumpers x
C610 6 Pins C610 JUMPERS Y VSS equipment which is Digital. That means the signal goes from zero to a certain level, then back to zero, then back to the same level, and back to zero. It is always the same polarity... that is, the signal just goes on and off. Set up for GM or Chrysler with center pins shorted to the outside edge pin in each row of three pins.

Explained another way, if you are using a digital vehicle, like Chevrolet or Dodge, set your jumpers so that the
UN-covered pins are on the inside, away from the edge of the board. For analogue-equipped vehicles, place your
jumpers so that the exposed pins are at the outside edge of the board. The fuzzy right picture just above has the
jumpers set up for digital, for a Plymouth Grand Voyager (Chrysler).

6-gold pins Foreign vehicles commonly use digital settings like GM, but you may find them with either type. Try the installation set up
one way, and if the pulses fail to operate normally, reverse the jumpers and test the other way. Pulses normally operate on a rate which follows the speed of the vehicle, they stop when you stop, and they will be present whether you are moving forward or in reverse. TECH TIP: You can test your wiring by disconnecting the pulse lead at the far end of the run, right at the VSS pick-up point, then holding the negative side of a flashlight battery against a chassis ground bolt, and tapping your wire against the tip of the battery several times. if your key is on, and the meter is in pulse counting mode, it should count the pulses you are making. If there is a pulse divider in the circuit, remember to tap enough times to cause the divider to put out a pulse.

If the pulse divider is set for divide by 16, you will have to tap the battery 17 times to see one pulse recorded!