|
Pete, well you said before you were working on a Deere "B" & if that is so you should have a 6 volt Wico XH dstriburtor, [s/n XD-xxx,xxx]. ~On the Wico 6 volt XH distributor the best place to check for power is to remove the distributor cap, then you should find a wire junction screw near the right lower corner of the points breaker plate [you should see the resistor wire coming from a hole in the housing & the coil's primary wire coming from the coil attached there]. With the ignition switch [turned on] & the points OPEN you should have close to battery voltage at that terminal screw. With the points CLOSED the voltage should drop to 4-5 volts. If you don�t have any voltage period, you have either a burnt up [open] resistor, or the terminal stud sticking out the front of the distributor is rusted & corroded & not passing current [common on the XD]. If the terminal post sticking out the front is corroded you have a couple of choices,,, first, you can try to remove the nuts & clean the post & nuts [that�s risky as the stud usually breaks off], or second, wire brush the post & stud & use a little file on the exposed nuts to clean them, then cut the attached wire & add a new crimp on terminal end, then install it on the remainder of the stud with a new nut & washer. [that usually works good] ~If you have power at that internal terminal screw with the points both open & closed, your resistor & power stud are both good & are passing current. If opening & closing the points doesn�t change the voltage on that junction screw from battery voltage to down around 4-5 volts you have a bad coil, defective points, open or short in an internal wire, or poorly grounded distributor or breaker plate. ~If the voltage at that terminal screw is always at battery voltage [even with the points closed] try using a jumper wire from the tractor frame or other CLEAN ground & touching the points wire connection screw on the side of the points, if the voltage at that resistor junction screw then drops to around 4-5 volts you have a points problems [probably oxidized points], or poor breaker plate ground. If the voltage at that junction screw is always 4-5 volts or under you have a short to ground in the points, or short to ground in the condenser, or shorted coil. If there is/was a short to ground in the coil or the wire running from that junction screw to the coil you probably would have a burnt up resistor [that resistor is very fragile]. Be very careful when using a jumper wire inside that distributor as you NEVER want to ground the resistor junction screw or the wire between the resistor junction screw & the coil, or there is a good chance the resistor will burn up very quickly. Grounding anything on the points side of the coil won�t hurt the resistor so keep that in mind when working on that XH/XD. ~If you do in fact have a 6 volt Wico XD [the �B� should] you can use an ohmmeter & measure the resistance of the dropping resistor [it should be somewhere between .8 & 1.2 ohms. You can also measure the coil�s resistance,,, the coil�s primary resistance [between power wire that hooks to that resistor junction terminal & the coil wire hooked to the points] should probably be somewhere around .5 to 1 ohms & the coil�s secondary resistance [measured between the coil center contact button & coil's ground wire] should probably be somewhere between 5.5 & 8 K ohms ~Now that I have probably really confused you with the above I will give you a quick & dirty way to test the coil & it�s output� First, remove the distributor cap, then fasten a wire [a paper clip works good] to one of the cap attaching screw holes & bend to within 1/8� of the coil�s center contact button, now turn the ignition switch on & crank the engine & look for a blue spark to arc between the wire & coil button [if you have a nice blue spark, the coil, points & condenser are good. If you don�t get a spark while cranking, turn the engine so the points are open & with the ignition turned on use a screwdriver & wiggle it between the open points [if you get a blue spark now you have dirty or malfunctioning points. If you still don�t get a spark check for power at the resistor junction terminal inside the distributor, then check for power at the points terminal on the points [points must be open] if you have power at the points, try disconnecting the condenser & then wiggling the screwdriver between the open points again [if you get a spark now you have a shorted condenser [you will have to pull the breaker plate out to access the condenser [it's burried in a pocket in the lower L/H corner of the distributor housing] . If you still don�t see a blue spark suspect the coil is bad�..
|
