| Author | Message | ||
| LOUIS KOLBE (Gmc4106)
Registered Member Username: Gmc4106 Post Number: 1 Registered: 8-2006 Posted From: 72.84.21.68 Rating: N/A |
CAN ANYONE TELL ME WHAT THE VOLTAGE TO THE FIELD TERMINAL SHOULD BE WITH SWITCH ON, ENGINE OFF. HAVE A NO CHARGE SITUATION AND WOULD LIKE TO SEE IF THE REGULATOR IS OK. I NOW HAVE 1.47 VOLTS. THANKS SO MUCH FOR ANY HELP; LOU | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 557 Registered: 1-2003 Posted From: 67.142.130.21 Rating: N/A |
What model of alternator do you have, and what regulator? | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 187 Registered: 8-2006 Posted From: 207.231.80.150 Rating: N/A |
Master switch on, eng dead=nearly battery voltage, or 10 at least, on the field term. 1.47 is way short. Do you have battery voltage at the battery terminal of the regulator with switch on? You should have batt voltage at the reg batt terminal, AND nearly that much at the field term, on both the reg and the alt, if everything else is ok. A simple test, is to disconnect the field wire from the alt, and jump the alt field term with 12 V positive. If everything gets bright, and you hear the engine work harder, the alt is ok, the problem is in either the regulator, wires, or the control circuits. Make sure you have 12V to ground from the alt output terminal before you jump the field, otherwise it will be very hard on the alt. Don't leave the jumper on for more than a second or so, either. Owning an MCI, I'm not up on the control circuits on a 4106, but the alternators and regulators all work the same. Mine has an electrical nightmare which won't let the alt charge until air pressure builds enough to tension the belt, AND keeps the no charge light off while it's keeping the alt off. Also, no charge=no air conditioning, which really keeps the one big belt from slipping. So, try it, and post back, please. George | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 558 Registered: 1-2003 Posted From: 67.142.130.37 Rating: N/A |
"the alternators and regulators all work the same" Umm, no. Some regulators regulate the NEGATIVE side of the field. For example, on my Delco 50DN, one field terminal is hard-wired to +24v, and the other field terminal goes to the Delco-Remy regulator, which modulates the ground side of the system. Hence my question about what model alternator and regulator. Please, everyone, let's know all the permutations of how these systems MAY be put together, before we dispense unequivocal advice. Otherwise, at least *say* that you are guessing. -Sean http://OurOdyssey.BlogSpot.com | ||
| LOUIS KOLBE (Gmc4106)
Registered Member Username: Gmc4106 Post Number: 2 Registered: 8-2006 Posted From: 72.84.21.68 Rating: N/A |
SEAN,IN ANSWER TO YOUR QUESTION ON WHICH GEN I HAVE, IT'S DELCO- #1117670- GEAR DRIVEN- HOT OUTPUT, 220 AMPS,14 VOLTS | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 191 Registered: 8-2006 Posted From: 76.168.69.233 Rating: N/A |
Sean, Louis did say field TERMINAL (singular), which excludes negative controlled field alternators. Aside from buses, etc. Chrysler Corp has used negative field control since 1973, when they went to a solid state regulator. Also, a 50DN was not stock to a 4106, and there was no indication that the original alt had been changed. As you are well aware, somehow in all alternators out there, some method of excitation, and control is required. Also, the battery terminal on your regulator has +24V on it, for the reg to use as reference and control current. Had Louis said "field terminalS," my response would have been different. Don't anybody take this as a flame, because it is NOT, Sean and me talk off-board, also. I am expecting Sean to publish a well-researched, and well illustrated diagram, on how to troubleshoot this charging system, which is why he asked for the make and model. I wasn't guessing when I said what I said, I applied Sutton's law to my diagnosis. (Willie Sutton was the bank robber who when asked why he robbed banks replied, "cause that's where the money is!") My quick and nasty troubleshooting advice stands, and won't do any more damage to the already ailing charging system. HTH, more. George | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 559 Registered: 1-2003 Posted From: 67.142.130.42 Rating: N/A |
Louis, Sorry for the delay. For some reason, I never got an email that this thread was updated. According to what I can find, your 1117670 alternator (which is a Delco series 50DN, commonly found in buses) accepts what is known as "B circuit" regulation. According to my cross-reference, the correct Delco regulator is a 9000551. This would have been the stock setup on your coach. "B Circuit" means that, as George surmised, your regulator controls the positive voltage to the field, and the other field terminal (if any) is connected to ground. I say "if any" because, also as George writes, there may only be one field terminal external to the case -- the other side of the field may simply be grounded to the alternator case internally. That said, I believe that this particular alternator will have two field terminals, labeled "F1" and "F2". One should be wired to the regulator, and the other to ground. I try not to make any assumptions about these things, because on a coach that old, who knows what changes may have been made to the electrical system from stock, up to and including changing the alternator and regulator, possibly to an "A circuit" style. For example, as you know, a common modification is to change older positive-ground systems to negative ground, for many good reasons. In any case, from what I can find your regulator should have a voltage set point of 14.2. And, George is right, you should be seeing something in the neighborhood of 12 volts on the field terminal connected to the regulator. Here's what I would check, in order: 1. All regulator connections. You should have three or four: one marked "G" or "GND", one marked "F" or "FLD", one marked "B" or "Batt", and one marked "I" or "IGN". Test the G terminal for good ground with an ohmmeter. Test the B terminal for good battery voltage -- you should see about the same reading as you get directly on the battery positive terminal. And test the FLD connection for good continuity to the field terminal on the alternator with an ohmmeter. The I terminal should have battery voltage on it when your ignition key is in the "on" position. 2. Remove the field wire from the alternator and measure resistance between the two field terminals, or between the single field terminal and ground. I don't have the service manual for your alternator, but I can tell you at least that you should read some resistance -- not a dead short. Make sure you set your ohmmeter on a low scale. 3. If all these check out good, I would remove the regulator and take it to a good alternator shop. They will be able to test it for you. Unlike the alternator, the regulator is easy to remove and carry in to the shop for testing. If it tests bad, replacements for this model are available from several companies, not just Delco. Do a web search on "Delco 9000551" and you should come up with a few cross-references. 4. If the regulator tests good at the shop, I would definitely NOT follow George's advice to jumper the field terminal direct to battery positive. That's because there may very well be a problem internal to the alternator, and putting a full 12 volts across the field terminals may do more damage. Instead, if the regulator checks out and you've tested all wiring as outlined above, I'd bite the bullet and pull the alternator out for bench-testing. Hope this helps. And just a quick reply to George: Your advice happened to be mostly right, in this case. But see my note above about how these systems are often changed out during the life of the coach. What I was reacting to, in my earlier post, was your sweeping statement that "... alternators and regulators all work the same ...": this is definitely not true, as we have now discussed, and a person new to the field could easily have been misled by it. Remember, other people are following along, not just the original poster. Had you clarified up front that you were making certain assumptions about A-circuit versus B-circuit based on the model of coach, or clues in the original question (as you did later on), then I would not have felt the need to jump in with the correction -- I'd hate to see someone with an A-circuit coach jumper his field terminal to battery positive! -Sean http://OurOdyssey.BlogSpot.com | ||
| Richard Bowyer (Drivingmisslazy)
Registered Member Username: Drivingmisslazy Post Number: 1922 Registered: 1-2001 Posted From: 75.108.76.30 Rating: N/A |
Sean, flashing the field with full battery voltage was always an accepted practice in about any situation I have ever seen. A quick flash with a 18-20 gauge clip lead is pretty common practice and i do not think it will do any damage. Just my opinion however. BTW, I believe I@N quit sending out emails some time ago do to some problems he had of sending out too many. Richard | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 195 Registered: 8-2006 Posted From: 76.168.69.233 Rating: N/A |
Sean, One little thing in regard to your item 4. In my original post, I said "make certain that battery voltage is available at the alternator output terminal." This tells US that there is continuity to the battery positive, or in other words, a place for the output to go! THAT WHOLE SENTENCE WAS TO PREVENT FLASHOVER DAMAGE DUE TO AN OPEN OUTPUT CIRCUIT. Now, what if the regulator tests good at the shop, and the regulator voltages were correct? That means that the alternator has been excited (the engineering term for field current) since the original failure occurred, right? Now you see why I suggested a one second jump, after confirming several other conditions. If my original advice was followed, it would identify the regulator as bad, if that was the problem, without a trip to the shop. Sean produces a much more academic and well researched post than I do. Mine are a hands-on, in-the-field, quick diagnosis. But I do need to make it clear that I pay close attention to the original post, and that my advice has been, "thought out" prior to posting. I will NEVER tell anyone to "jump" something without being aware of the consequences. This isn't a flame either! George | ||
| Sean Welsh (Sean)
Registered Member Username: Sean Post Number: 560 Registered: 1-2003 Posted From: 67.142.130.16 Rating: N/A |
Richard (and George), Yes, providing +12v directly to the field terminal (of a B-circuit alternator) is acceptable practice, both for flashing the field as Richard suggests, and for proving the alternator itself is working when the regulator is not, as George suggests. That being said, however, *one* possible cause of the very low reported voltage reading (1.47 v) at the positive field terminal is some type of low-impedance (short) condition in the field wiring. For example, there might be a spot in the field winding where the insulation has rubbed through, causing the excitation voltage to be quickly siphoned off to ground. Also, in this case, not enough of the field will be energized to produce good output. The regulator itself will protect the alternator in this case, by only providing a limited current to the (shorted) field terminal. However, if you connect the field terminal direct to battery voltage, under this scenario, you could end up melting something else in the field wiring. Or worse, depending on the strength of the batteries and the gauge of your jumper wire, you could end up doing some inadvertent welding. This is the reason why, given the reported symptom, I recommended, after checking all wiring, that the regulator be removed and tested, which I am guessing to be either a free or inexpensive procedure at most reputable alternator shops. If the regulator tests "good" and all wiring is correct, then the problem is in the alternator field windings itself, and, under that circumstance, I believe it to be risky to connect the field terminal direct to positive battery voltage. Hope this clarifies it. And, George, no flame-offense taken, and also, none intended. BTW, I'm pretty sure this is a solid-state regulator, and there are several good direct drop-in replacements for it on the market which will drive the existing 50DN alternator. Likewise, there are also direct replacements for the alternator, although, cost-wise, it may be more economical to have the aforementioned alternator shop re-wind it, if that turns out to be the problem. HTH. -Sean http://OurOdyssey.BlogSpot.com | ||
| Richard Bowyer (Drivingmisslazy)
Registered Member Username: Drivingmisslazy Post Number: 1923 Registered: 1-2001 Posted From: 75.108.76.30 Rating: |
Sean, you are, as always, correct and I definitely appreciate your detailed explanations into the theory of how some things operate. And George, your practical explanations are welcome reading also. In this particular problem, my feeling is that if there is already some internal damage to the alternator field then flashing it would not create any more damage than has already occurred since the field would have to be re-wound anyhow. Just my particular method of trouble shooting that may not be everybody's cup of tea. Richard Revision: And if it was not already damaged, then flashing it would not do any harm. (Message edited by DrivingMissLazy on June 17, 2007) | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 379 Registered: 7-2006 Posted From: 68.205.165.5 Rating: N/A |
Louis - Please remember to post the final results, and your remedy, to this -same thread-? The information will be archived for any others that may have the same problem in the future. | ||
| LOUIS KOLBE (Gmc4106)
Registered Member Username: Gmc4106 Post Number: 3 Registered: 8-2006 Posted From: 72.84.21.68 Rating: N/A |
I REALLY APPRECIATE EVERYONES HELP WITH THIS GENERATOR PROBLEM.I TRIED TO FOLLOW MY WIRING DIAGRAM BUT FOUND THE EARLY 4106 GEN SET UP WAS CHANGED IN THE LATER 4106'S, OF COURSE I HAD THE WRONG DIAGRAMS SO TRYING TO TRACE CONNECTIONS WAS NEXT TO IMPOSSIBLE. I WENT THROUGH ALL CONNECTIONS IN EACH ELECTRICAL COMPARTMENT CLEANED AS NEEDED,PRAYED OVER IT,JUMPED 12 VOLT TO THE BATT TERMINAL ON THE REGULATOR.IT TURNS OUT THAT A RELAY IS USED TO SUPPLY VOLTAGE TO THE REGULATOR WHICH WASN'T GETTING VOLTAGE TO OPERATE.I STARTED THE BUS AND THE GENERATOR WORKED, TOOK THE JUMPER OFF AND THE GENERATOR WORKED WELL WITHIN VOLTAGE PERAMETERS. HOWEVER THE VOLTAGE FROM THE GENERATOR NOW HAS A 1+/- VOLT OSCILATION BUT OTHER WISE SEEMS OK. HOW THE VERY LOW VOLTAGES CAME INTO BEING I HAVE ONLY SPECULATIONS. THANKS AGAIN,LOU | ||
| Tom Caffrey (Pvcces)
Registered Member Username: Pvcces Post Number: 1105 Registered: 5-2001 Posted From: 65.74.67.130 Rating: N/A |
Louis, in the 4106, and I'm sure, other models as well, there is a small current furnished through the field winding to cause the alternator to put out a very small amount of power if the engine is idling. It does not come from the regulator. If the engine is stopped, that small amount of power will give you the low voltage at the field terminal that you found. When you first start your engine, you have to rev it up to get the generator light to go out. Speeding up the alternator causes the output at it's relay terminal to rise enough to switch on the starter protection relay, which furnishes full power to the field system. If your regulator has a sensing relay that it gets it's power from, that relay will be turned on by the starter protection circuit. In turn, it will provide power to the regulator and the generator will begin producing power normally. The heating system is kept turned off by the same starter protection relay that sensed the voltage present at the relay terminal of the alternator. The surging that you see in the battery voltage is common because the regulator is quite slow switching the field on and off. With a heavy load, it's really not very much of a problem. There's more to that circuitry, but I think you've probably heard more than you wanted to know. I believe that the heating and over the road air condtioning are kept turned off if there is no power from the alternator because it would draw down the batteries in a very short time if it was left operating with a dead charging system. With a rear engine coach, it is all too easy to hit the starter button when the engine is running. I think that it would cause starter damage if that happened if the engine was turning very fast. For what it's worth. Tom Caffrey PD4106-2576 Suncatcher Ketchikan, Alaska |
