Alternator terminal question and other questions.

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CharlieO.

Guru
Joined
Sep 21, 2020
Messages
2,067
Location
Lake Champlain Vermont, USA
Vessel Name
Luna C.
Vessel Make
1977 Marine Trader 34DC
What is this terminal for? It seems to have an orphan ring terminal on it.
Also is there a way to repair that tab?
What is the best way to clean the alternator without complete disassembly?
First picture is the alternator still mounted. The alternator is currently on my workbench to replace the brushes and regulator.
8MR2018K
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Who is the mfgr.? Without that it could be many different mfgrs. each using different codes
Usually there are raised letters next to each nut/ wire attachment point. Those letters indicate the use or intention.
Usually those letters can be looked up on the net for the intended function.
Without those tidbits of info it is total guesswork and likely to be wrong.
You should be able to use the NET to look up those functions once you sort of the mfgr., and the labels/ raised letters.
 
Who is the mfgr.? Without that it could be many different mfgrs. each using different codes
Usually there are raised letters next to each nut/ wire attachment point. Those letters indicate the use or intention.
Usually those letters can be looked up on the net for the intended function.
Without those tidbits of info it is total guesswork and likely to be wrong.
You should be able to use the NET to look up those functions once you sort of the mfgr., and the labels/ raised letters.
It is an old Motorola 51a, original equipment on my Ford Lehman. I don't 't see any terminal markings on the alternator.
 

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We always cleaned our motor/generator sets in the Navy with low pressure air. 20-30 pounds to blow out the carbon dust left by the wearing brushes.
 
Consider buying a Delco to replace. It should be a drop in and give you 70 amps. They are pretty inexpensive online.
 
Consider buying a Delco to replace. It should be a drop in and give you 70 amps. They are pretty inexpensive online.
I have considered that but would like to do some rewiring before adding a bigger alternator.
I’ve got new brushes and a NOS voltage regulator to freshen this one up.
 
That broken tab looks like a stator tap to run a tach signal. The tab is usually made from some type of insulating material like phenolic. The orphaned ring terminal is probably the old tach signal. I take it you have a different way to get the engine rpm now.
 
It looks like the tach tap on my Lehman' s alternator. I've broken it and replaced it twice. The second time I made a new one out of an old circuit board corner. The way it was originally mounted it stuck out and would get caught on my pants when crawling around the engine. This last time I rearranged it so it's more protected inside the alternator and I'm more careful. I've also stopped wearing pants when doing engine maintenance.
 
That broken tab looks like a stator tap to run a tach signal. The tab is usually made from some type of insulating material like phenolic. The orphaned ring terminal is probably the old tach signal. I take it you have a different way to get the engine rpm now.
There is still one wire connected to it. My lower helm tach works but my upper helm does not. Is there usually just one wire to run both tachometers?
 
There is still one wire connected to it. My lower helm tach works but my upper helm does not. Is there usually just one wire to run both tachometers?
I believe that to be the method. I’ve never had dual helms so can’t guarantee it though.
 
It looks like the tach tap on my Lehman' s alternator. I've broken it and replaced it twice. The second time I made a new one out of an old circuit board corner. The way it was originally mounted it stuck out and would get caught on my pants when crawling around the engine. This last time I rearranged it so it's more protected inside the alternator and I'm more careful. I've also stopped wearing pants when doing engine maintenance.
Are you working in the engine room in your tightly whiteys? My engine room isn't quite clean enough for that yet.
 
There is still one wire connected to it. My lower helm tach works but my upper helm does not. Is there usually just one wire to run both tachometers?
My Perkins engines have mechanical tach senders but yes, there is just one wire to feed both helms. You likely have a bad wire or connection somewhere, or the tach itself is bad. You could try running a temporary wire to the dead tach to narrow it down.
 
Is there any reason I shouldn't replace the two ring terminals connected with the bolt on the broken tab with a male and female spade connector?
 
For ABYC compliance you would need to use a "captive" spade. This usually has hooks on the tips to keep it from pulling off. A spade is like a "fork" termination.

Do you mean a quick connect type? I would definitely avoid that. I think they are only allowed on lower amperage circuits and anyway I don't see why you would want to repeatedly undo an alternator connection.
 
For ABYC compliance you would need to use a "captive" spade. This usually has hooks on the tips to keep it from pulling off. A spade is like a "fork" termination.

Do you mean a quick connect type? I would definitely avoid that. I think they are only allowed on lower amperage circuits and anyway I don't see why you would want to repeatedly undo an alternator connection.
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These are the type I am considering, would the alternator tap be high voltage? I am just having a hard time finding something on hand to make a new tab from.
More than likely, I am just overthinking this broken tab issue.
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I would call that a quick connect. Voltage shouldn't matter, it would be amps you are concerned about. If it isn't part of the output circuit you should be OK there.

I'm speaking kind of generally because I don't exactly understand the issue you are trying to solve.
 
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