#26
IP: 64.20.183.217
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Quote:
The yellow wire is the EXCITER TERMINAL to the coil. "Connect the EXC terminal to the positive terminal of the coil using a 14 gauge wire so that the fields of the alternator will be excited when the ignition switch is turned on" Here's a pic of my old Moto 35 Alt with the Exciter Wire off the regulator...
__________________
-Jerry 'Lone Ranger' 1978 RANGER 30 Last edited by roadnsky; 09-20-2011 at 01:59 PM. |
#27
IP: 199.254.67.146
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Shawn, Jerry, Steve, everyone, thank you so much. I will post the outcome of my alternator investigation.
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#28
IP: 76.230.234.177
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Ok, the hunt continues...
Today, I first looked up the actual model number on the alternator plate and it is MR12N550. I could not find any product detail data on the unit since they are discontinued. However, I found through cross reference on Prestolite Website I then took the alternator to a local shop in Oakland (Buchanan Auto Eletrical) since they have the M5-197 regulator. The first thing I asked them to do is to bench test the alternator which they did. The test result, however, shows that the output voltage is 14V rather than the 18-20V I have been getting on the boat. They also said the current output is 30A which it should be putting out 60A. I was surprised to learn that the alternator, although a Motorola unit, is not the original 35A model and they guessed the output should be 60A. In addition, they said tha the unit is too hot. They said that since it is putting out 14V the regulator is sound. I asked them what else could cause the output to be 18-20V on my boat and why the output current is lower than what they expected. They said the only thing they can do is to open it up and rebuild it which will cost around $180. So, I took it back to my friend Rob's shop and took the unit apart to visually inspect if there are any obvious physical signs of damage (eg. loose or broken wires, burn mark, etc...) Here are the pictures which as you can see do not suggest any obvious damage. So, I put everything back together. Suspecting that my multimeter may not be caliberated properly I borrowed Rob's digital multimeter. Back on the boat I put the alternator back in and reconnected the wires. After double checking the wiring I fired up the A4 again. Again, I tested the voltage output but with Rob's digital unit. This time it shows 17.2V on the positive side of the coil. The negative side shows 9.4V. That is clearly still way high on the positive side. Is the negative side voltage right? What should it be? Judging by the outcome of Bradley's experience (see Alternator Output > 18V the shop test outcome is not always reliable. I am guessing that my regulator is also the cause of the problem. Last edited by Triton106; 09-22-2011 at 01:44 AM. |
#29
IP: 64.20.183.217
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Triton-
Do you want my old 35 Motorola? It was working fine when I changed it out last year for the 55. Yours if you want it. Just pay the shipping.
__________________
-Jerry 'Lone Ranger' 1978 RANGER 30 |
#30
IP: 208.89.140.11
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Interesting, looking at the pictures is the red wire insulation cracked by the case ? Could be a shadow.
When you measure the vdc, try the ac scale, that will tell you if there's an ac component in the voltage for the + side of the coil. The voltage output from the alternator is changed from ac to dc by the diodes. I tried looking for a schematic but couldn't find one. I would assume that it uses the exciter wire to also sense the voltage and to drive the regulator, less voltage, higher output. I would check and or replace the yellow wire connector which goes to the + side of the coil. The neg side of the coil goes to the points in your distributor, this is what conducts the current flow through the coil. This would be a ac voltage in rhythm with the points opening and closing. Looks like the regulator was already replaced as the transpo was used. If the 17 vdc was on the battery then the battery life will be shortened. Steve |
#31
IP: 107.0.6.242
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Looking at the potentiometer (spelling?) it seems that the adjuster could be turned down (counterclockwise) a bit more. Why not give it a shot? Nothing to lose...but do not force it beyond it's (very delicate) stop.
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#32
IP: 199.254.67.146
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Jerry, that would be great! My electrical load is very low so a 35A is more than sufficient. I appreciate your generousity. I will PM you with my address. Just let me know the shipping cost.
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#33
IP: 199.254.67.146
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Hanley, sharp eyes. I did not realize that blue thing is the voltage adjuster. To be honest I have never tested the alternator output before since it always worked. For all I know the high output problem could have been there for a long time. Like you said, nothing to lose. I will give that a go.
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#34
IP: 64.20.183.217
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Quote:
Now you can take your time fixing the other one. PM me and I'll get it out to you next week...
__________________
-Jerry 'Lone Ranger' 1978 RANGER 30 |
#35
IP: 206.125.176.3
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Triton, if you trash that alternator, I'll buy the regulator!!
__________________
-Shawn "Holiday" - '89 Alura 35 #109 "Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!) |
#36
IP: 199.254.67.146
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Shawn, I don't if it is the alternator or the regulator that is at fault. It may well be the regulator.
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#37
IP: 107.0.6.242
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I'm afraid you are going to have to put aside that info from the alternator shop. Most of these shops just have an electric motor hooked up to an adjustable belt and bracket rig and they run it up to 2000 rpm or so and read the output on an ammeter. Most do not read voltage. If you just bypass your regulator with a direct connection from alternator output to field and watch your boat ammeter you can tell if it is the alternator or regulator that is the problem. Do this for only a few seconds as the alternator will be putting out maximum amps (that the battery will accept) at the maximum voltage the alternator is capable of at that rpm and charging rate. You are your own best diagnostician.
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#38
IP: 206.125.176.3
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Hanley - you get the award for $0.50 word of the day.
__________________
-Shawn "Holiday" - '89 Alura 35 #109 "Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!) |
#39
IP: 76.230.234.177
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Well, what began as an interesting hunt is becoming a frustrating ordeal.
I tried adjusting the potentiometer as suggested by Hanley but could only lower the ouput by less than 0.4v (from 17.4v to about 17.0, end-to-end). I am not even sure if that difference came from different engine idle speed or the result of the potentiometer adjustment. I then re-examined and re-did some of the wiring to make sure there were no bad or corroded connections. That did not work either. At this point, I am at the end of my wits and just going to wait for Jerry's old alternator (thanks Jerry!) before my alternator drive me crazy! It's not worth it... |
09-24-2011, 08:56 AM |
hanleyclifford |
This message has been deleted by hanleyclifford.
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#40
IP: 173.166.26.241
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Sometimes the high tech stuff drives me crazy too (short trip). Found this for $25. Old fashioned contact style, adjustable (but sensitive), works great.
Last edited by hanleyclifford; 07-13-2016 at 08:33 PM. |
#41
IP: 72.57.103.166
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Quote:
Got home late last night and looked in the garage to make sure I still have the promised ALT. It's there. (whew!) I had to leave this morning on another trip, but will be home Wednesday and it'll be on the way. Hang in there...
__________________
-Jerry 'Lone Ranger' 1978 RANGER 30 |
#42
IP: 76.230.234.177
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Thanks Jerry . In truth, I debated if I should take a chance and go sailing today because the engine will still run with alternator putting out 17v. Clearly it is not good for the coil, the electrical ignition, and the battery. I quite recklessly motored out because the wind was good, praying that the alternator will not fry something again . Luckly for me nothing that dramatic happened.
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#43
IP: 76.230.234.177
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Shawn, you can have my defective alternator/regulator when I receive Jerry's unit and see if you can salvage it
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#44
IP: 174.65.54.224
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Triton, I don't know what kind of charging system you have but if you have solar (like i have for one battery) you can probably run on just the battery for quite a while. Disconnect the alternator if the high amps/voltage to your coil is your concern.
This might be my stupidest post ever but , if you gotta be on the boat and get it out to good sailing grounds, this might not be the worst idea ever. Anybody?
__________________
"Jim" S/V "Ahoi" 1967 Islander 29 Harbor Island, San Diego 2/7/67 A4 Engine Block date |
#45
IP: 76.230.234.177
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Thanks Jim, I don't think my decision to use the engine was rational and would not try to defend that. That said if the engine did fail on me I would be able to sail back without having to call for tow since I mentioned the wind was quite good (10-15 knots).
I do have a small solar panel trickle charger but yesterday was overcast so I knew I could not depend on it. |
#46
IP: 174.65.54.224
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I guess my point was, instead of running the risk of frying the coil, EI and the alternator, (3 expensive parts to replace) you could run it as if it was on the bench, just off the battery.
Remove alt belt, connect jumper from + coil to starter post. I bet it would continue to run with battery as low as 6 volts. Your action is not indefensible. Sailing season is short, shorter for those that work 5 days a week. And you might be waiting a while for Jerry to send you his old alternator. Maybe my logic is flawed. Correct me if I'm wrong.
__________________
"Jim" S/V "Ahoi" 1967 Islander 29 Harbor Island, San Diego 2/7/67 A4 Engine Block date Last edited by jpian0923; 09-25-2011 at 04:15 PM. |
#47
IP: 173.166.26.241
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Nothing wrong with running without an alternator but the key is to disconnect the field and alternator output terminals. It's OK to let the alternator spin itself crazy (unconnected).
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#48
IP: 174.65.54.224
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Thanks for the input Hanley. It's nice to know it's possible if needed in an emergency.
__________________
"Jim" S/V "Ahoi" 1967 Islander 29 Harbor Island, San Diego 2/7/67 A4 Engine Block date |
#49
IP: 107.0.6.242
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Here's what I keep on board for when I get really disgusted with the regulators I have. This is cobbled with 10w bulbs and 1 ohm (10 watt) resisters. Cheap and easy way to supply limited voltage to the field if you get in a fix. Red is 12v input and blue is ouput to the field, switches in parallel.
Last edited by hanleyclifford; 07-13-2016 at 08:33 PM. |
#50
IP: 76.230.233.30
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Woa Hanley, that's some hard core engineering... Care to explain how that works in lieu of a regulator?
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Tags |
alternator, regulator |
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