{"id":74,"date":"2010-04-19T22:49:13","date_gmt":"2010-04-20T02:49:13","guid":{"rendered":"https:\/\/cubcadetman.com\/cc\/?p=74"},"modified":"2014-02-17T13:42:17","modified_gmt":"2014-02-17T18:42:17","slug":"checking-a-mechanical-voltage-regulator","status":"publish","type":"post","link":"https:\/\/cubcadetman.com\/cc\/how-tos\/2010\/04\/checking-a-mechanical-voltage-regulator\/","title":{"rendered":"Checking a Mechanical Voltage Regulator"},"content":{"rendered":"

\"voltage<\/a>\"voltage_regulator<\/a><\/p>\n

Voltage Regulator Wiring<\/strong><\/p>\n

Bat — connects to the battery (Gray wire if original wiring); may connect to the battery through an ammeter and key switch<\/p>\n

Gen — connects to the armature terminal on the starter\/generator (light blue wire if original wiring); armature terminal will also have wire from solenoid<\/p>\n

F — connects to the field terminal on the starter\/generator (yellow wire if original wiring); only wire on the starter\/generator field terminal<\/p>\n

Gnd — connects to ground on tractor frame (white\/blace wire if original wiring)<\/p>\n

How a voltage regulator works<\/strong><\/p>\n

In all the discussion that follows, when I refer to the generator, it\u2019s actually the starter\/generator used on older model Cub Cadets.\u00a0 The discussion also refers specifically to the type of regulator shown above.\u00a0 CAUTION:\u00a0 A battery can explode as a result of a spark or overcharging.\u00a0 Wear appropriate safety gear when working on the charging system, especially safety glasses.<\/p>\n

\"voltage_regulator<\/a>At the left is a \u201cpictorial schematic\u201d of what I think the wiring is on the voltage regulator.\u00a0 Again, I take no responsibility for the accuracy of this schematic.\u00a0 Without destroying the regulator, I couldn\u2019t check all the connections I\u2019ve shown.\u00a0 Notice the points on the left are normally closed and those on the right are normally open.<\/p>\n

The voltage regulator has two functions.\u00a0 1) Regulate the voltage to the battery so it doesn\u2019t exceed 14 volts (actually 14.2 volts).\u00a0 2) Disconnect the battery from the generator when the voltage from the generator gets too low as when the generator is turning slowly or stopped.\u00a0 In the picture of the regulator above, the coil on the bottom regulates the voltage (regulator coil) and the top coil (cutout coil) disconnects the battery from the generator.\u00a0 I had to troubleshoot the bottom section of the regulator and this discussion centers mainly on that portion.\u00a0\u00a0 In the schematic, the regulator section is on the left and the cutout is on the right.<\/p>\n

If the field terminal on the generator is connected directly to ground, it will produce a voltage at the armature terminal of the generator.\u00a0 This voltage will exceed 16 volts and will overcharge the battery if not regulated.\u00a0 For the voltage regulator pictured above, a wire from the field terminal of the generator would be connected to the field terminal of the regulator (bottom left side of picture).\u00a0 The field terminal of the regulator is connected to ground (bottom right terminal in the picture) through the lower set of points shown in the picture. (The frame of the points is insulated from the base of the regulator.)\u00a0 This connection is shown in the schematic by a green line.\u00a0 If the points remained closed, the generator would produce over 16 volts and overcharge the battery.\u00a0 The points must open to \u201cunground\u201d the field terminal of the generator and prevent overcharging.\u00a0 On an actual voltage regulator, one end of the regulator coil wire is connected to the generator terminal of the regulator (center left terminal) and the other end is connected to ground.\u00a0 As the generator voltage increases, the magnetic pull of coil on the points increases.\u00a0 When the voltage at the generator terminal reaches around 14 volts, the magnetic filed generated by the coil pulls the bottom section of the points downward, breaking the field connection to ground.\u00a0 With the field connection disrupted, the generator output voltage drops, the voltage to the generator terminal of the regulator is reduced, the magnetic force of the coil is decreased and the spring pulls the points closed again.\u00a0 The points alternately open and close to regulate the voltage output.\u00a0 This whole process occurs so rapidly that the output voltage remains around a constant 14 volts for all practical purposes.<\/p>\n

The procedure I used to check the regulator section of the voltage regulator<\/strong><\/p>\n

The system I checked was only outputting 4 volts at the generator armature.\u00a0 I used the following procedure to diagnose the problem.\u00a0 This procedure assumes that you\u2019ve checked all connections and grounds to make sure they\u2019re good.\u00a0 With a properly working voltage regulator, you should read around 14 volts between the armature connection of the generator to ground.\u00a0 If the system is not outputting 14 volts to charge the battery, follow this procedure.\u00a0 Leave a voltmeter connected from the armature connection of the generator to ground for these tests.\u00a0\u00a0 You\u2019ll need a couple jumper wires (two wires with alligator clips on each end works well), an ohmmeter, and a voltmeter with a range of 0 to 16 volts.\u00a0 I prefer an analog meter for these checks but a digital voltmeter can be used.\u00a0 You can jump ahead on these checks and work backward through the procedure if you suspect a particular problem.\u00a0 The procedure also assumes the generator is outputting less then the required 14 volts before each test is performed.\u00a0 Once you get 14 volts, further testing will do you no good.<\/strong><\/p>\n

First, check that the generator is capable of outputting the required voltage.\u00a0 Connect a jumper wire to a good ground.\u00a0 With the engine running at a fast idle, temporarily touch the other end of the jumper wire to the field terminal on the generator.\u00a0 (Don\u2019t race the engine for this test or you can overheat and burn something up.)\u00a0 The voltmeter should rapidly read above 16 volts.\u00a0 (Don\u2019t operate the regulator over 14 volts for an extended period of time.)\u00a0<\/strong> If voltmeter reading doesn\u2019t exceed 16 voltss, recheck your ground and try running the engine a little faster.\u00a0 If the generator still fails to reach 16 volts with this test, it needs to be repaired and\/or replaced.<\/p>\n

Assuming the generator passes this test and with one end of the jumper still connected to a good ground (and the engine at a fast idle) touch the other end of the jumper to the field terminal (marked F) on the voltage regulator (bottom left hand connection in the above picture).\u00a0 Again the voltmeter should read above 16 volts.\u00a0 If it doesn\u2019t, you have a bad connection or wire between the generator and the voltage regulator.<\/p>\n

With the cover of the voltage regulator removed, touch the jumper wire to the left side (fixed side) of the point bracket.\u00a0 Again the voltmeter should read above 16 volts.\u00a0 If it doesn\u2019t you have a bad connection between the regulator terminal and the left side of the points.\u00a0 In the regulator picture above, there\u2019s a silver wire that makes this connection.<\/p>\n

Next, touch the jumper to the right hand side of the points (somewhere around where the spring is connected on the right hand side in the above picture).\u00a0 If the voltmeter fails to register above 16 volts, there\u2019s poor contact across the points.\u00a0 Shut off the engine and drag a sheet of paper back and forth through the points.\u00a0 Use your ohmmeter to check the resistance.\u00a0 It should read something less then one ohm.\u00a0 Continue to clean the points until you get this reading.\u00a0 If your system is still not charging when you restart the engine, again make the above ground check to make sure you\u2019re getting a connection through the points.\u00a0 When the system is working properly these points will rapidly open and close to produce a 14 volt charge to the battery.\u00a0 IF THE POINTS STAY CLOSED YOUR POINTS ARE STICKING OR YOU HAVE A BAD COIL.\u00a0 There is a possibility that the spring tension is too high but I\u2019ve never messed with the spring tension.<\/p>\n

Assuming the system passes all the tests above, touch the jumper to the ground terminal (marked GND) of the voltage regulator (bottom right terminal in the above picture).\u00a0 If the voltmeter reads above 16 volts during this test, then the regulator is not properly grounded.\u00a0 You now have checked the complete field circuit and the voltage regulator has the same effect as shorting the field at the generator directly to ground.<\/p>\n

\"voltage<\/a><\/p>\n

Again, the voltage regulator shown consists of two coils.\u00a0 The lower coil (in the pictue) with the smaller windings \u201cregulates\u201d the voltage;\u00a0 i. e.; it causes the generator to charge at around 14 volts.\u00a0 The top coil (with the heavier windings) is used to disconnect the voltage regulator from the battery when the engine is not running or running too slowly to charge the battery.\u00a0 Otherwise, the battery would discharge through the voltage regulator and generator windings when the engine isn\u2019t running.<\/p>\n

Unfortunately, I couldn\u2019t figure out a way to check the individual coil resistances to make sure the coils were good.\u00a0 Notice in the schematic there is a connection between the GEN terminal and GND for both coils.\u00a0 So you cannot check the resistance of either coil individually without cutting a wire and I didn\u2019t want to do that.<\/p>\n

As I explained earlier, I know the function of the top coil and points in the picture.\u00a0 But I can only speculate how they work.\u00a0 This portion of regulator I was working on worked properly so I had no reason to investigate further.\u00a0 I do know that with the generator producing the correct output voltage (14 volts), the magnetic pull of the top coil pulls the top points closed connecting the generator to the battery.\u00a0 That will allow the 14 volts being produced by the generator to charge the battery.\u00a0 Notice there are two sets of windings on the coil.\u00a0\u00a0 When the generator output reaches somewhere around 14 volts, the magnetic force produced by the coil that connects the generator terminal to ground will pull the points closed connecting the armature to the battery.\u00a0\u00a0 (The red line in the schematic)\u00a0 The coil windings in the \u201cred line circuit\u201d add additional magnetic pull on the points to help hold them closed.\u00a0 When the voltage output from the generator drops below battery voltage, current from the battery will flow from the battery to the generator (reversed from the direction when charging).\u00a0 This creates a magnetic force that opposes the magnetic force produced by the other winding on the cutout coil allowing the spring force to open the points and break the connection between the generator and battery.\u00a0 The open points prevent the battery from discharging through the generator.<\/p>\n

I can tell you how to check the point connection for this section (the cutout section), but it\u2019s a bad way to test!!\u00a0 With everything connected and the engine shut off, if you manually close these points, it will cause the starter\/generator to turn.\u00a0 If you look at the schematic you can see this would connect the battery to the armature causing rotation.\u00a0 But, this is a really bad idea for a couple of reasons.\u00a0 First, you\u2019re running starter current through a wire that\u2019s not large enough to carry it.\u00a0 The wire that runs from the solenoid to the armature that\u2019s used to start the engine is 10 gage.\u00a0 The wire in the charging circuit is probably only 14 gage.\u00a0 The second reason not to do this is that there\u2019s a good chance the points will stick closed.\u00a0\u00a0\u00a0 So, in summary, it\u2019s NOT A GOOD IDEA.<\/p>\n

If anyone has additional insight into how the regulator works\u00a0 or has a correction to any of my above discussion, I\u2019d be glad to hear from you.\u00a0 In any correspondence, please indicate if you wish for me to acknowledge your help.\u00a0 Be aware, however, if I receive the same information from two individuals and one doesn\u2019t want acknowledgment, I\u2019ll obviously use the information from that source.\u00a0 I\u2019ll be glad to furnish anyone with documentation to that effect.\u00a0 Thanks in advance for any help.<\/p>\n

Addendum:<\/strong>\u00a0 I decided since I was at it, I\u2019d include a short discussion of a later model regulator as well.<\/p>\n

\"newer<\/a>\"newer<\/a><\/p>\n

Notice that this regulator has the \u201cGEN\u201d terminal located on the back side.\u00a0 The regulator coil is the bottom coil in the left hand picture and the cutout coil is on top.\u00a0 From the bottom of the left hand side to the top, the terminals are:\u00a0 \u201cF\u201d, \u201cBAT\u201d and \u201cL\u201d.\u00a0 You can see the \u201cGEN\u201d terminal in the picture on the right.\u00a0 It\u2019s centrally located on the left side of the back in the picture.\u00a0 The regulator base acts as the ground.<\/p>\n

How it works<\/strong><\/p>\n

I think the \u201cpictorial schematic\u201d should look something like this:<\/p>\n

\"newer<\/a>Although the regulator wiring looks a little more complicated, it seems it should work and be debugged in the same way.\u00a0 Notice that the field terminal is initially connected to ground (green circuit in the schematic) and opens as a magnetic field is built up by the voltage from the generator.\u00a0 Again, as the generator voltage increases, the points would open breaking the connection to ground and regulating the voltage.\u00a0 If you notice on the picture of the back side of the voltage regulator, there\u2019s something that runs from the field terminal, across the back of the regulator and grounded to the case.\u00a0 I think this is just a resistor.\u00a0 This would mean that under operation, the field connection would never be completely broken from ground.\u00a0 (See the pictorial schematic)\u00a0 There would always be a connection to ground through this resistance.\u00a0 The first regulator I discussed also had this resistance, but I left it out of the schematic to simplify the discussion.\u00a0 I don\u2019t know for sure, but have a feeling it\u2019s used to smooth out the voltage and maybe save some wear and tear on the points by reducing the magnitude of the current flowing through the points.\u00a0 With the resistance in the circuit, the field winding connection to ground will never be completely broken so that the voltage would never tend to drop to completely zero if everything is working properly.<\/p>\n

This time there\u2019s two windings on both coils.\u00a0 The two windings on the cutout coil would behave just like the two windings on the cutout coil discussed earlier.\u00a0 It seems that the second winding on the regulator coil would help open the points and produce additional voltage regulation.\u00a0\u00a0\u00a0 Also, notice that the \u201cL\u201d terminal will always be at the same voltage as the \u201cBAT\u201d terminal.\u00a0 There is a direct connection from the \u201cBAT\u201d terminal to the \u201cL\u201d terminal within the voltage regulator.\u00a0 I think the \u201cL\u201d terminal is generally used to supply voltage for the auxiliary circuit on a Cub Cadet.<\/p>\n

As mentioned previously, if you can add additional information on how this regulator works or a good trouble shooting procedure, please let me know.\u00a0 Any place in the discussion that I use the expression \u201cI think\u201d, I could use some verification that my thinking is correct.\u00a0 As before, let me know if you want acknowledgement for this help placed in the discussion.<\/p>\n

Voltage Regulator Wiring<\/strong><\/p>\n

L — assesory wiring (may have no wire connected if no lights)<\/p>\n

Bat — connects to the battery (Gray wire if original wiring); may connect to the battery through an ammeter and key switch<\/p>\n

F — connects to the field terminal on the starter\/generator (yellow wire if original wiring); only wire on the starter\/generator field terminal<\/p>\n

Gen — connects to the armature terminal on the starter\/generator (light blue wire if original wiring); armature terminal will also have wire from solenoid<\/p>\n

As stated above, the ground is the regulator case and mounting<\/p>\n","protected":false},"excerpt":{"rendered":"

When I had a regulator problem with one of my Cub Cadets, I set out to find out how the regulator worked. I couldn\u2019t find any good, simple discussions on the subject, so I played around until I found how I think everything works. This article is based on my ideas and impressions and isn\u2019t necessarily correct but seemed to make sense to me. I take no responsibility for the accuracy of my ideas. <\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[2],"tags":[],"class_list":["post-74","post","type-post","status-publish","format-standard","hentry","category-how-tos"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p4lT6g-1c","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/cubcadetman.com\/cc\/wp-json\/wp\/v2\/posts\/74","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cubcadetman.com\/cc\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/cubcadetman.com\/cc\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/cubcadetman.com\/cc\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/cubcadetman.com\/cc\/wp-json\/wp\/v2\/comments?post=74"}],"version-history":[{"count":4,"href":"https:\/\/cubcadetman.com\/cc\/wp-json\/wp\/v2\/posts\/74\/revisions"}],"predecessor-version":[{"id":84,"href":"https:\/\/cubcadetman.com\/cc\/wp-json\/wp\/v2\/posts\/74\/revisions\/84"}],"wp:attachment":[{"href":"https:\/\/cubcadetman.com\/cc\/wp-json\/wp\/v2\/media?parent=74"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cubcadetman.com\/cc\/wp-json\/wp\/v2\/categories?post=74"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cubcadetman.com\/cc\/wp-json\/wp\/v2\/tags?post=74"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}