Re: 1947 Super Clipper ammeter
Posted by HH56 On 2011/10/4 18:10:46
There is not much electrically to go wrong with the ammeter. It is located in series in wiring between generator and battery. Essentially a flat strip of metal connecting one post to the other and shaped or configured to make sort of a loop. Current flowing thru that strip & loop makes it slightly magnetic which works on a piece of metal suspended near or inside the loop & attached to the needle. More current = stronger magnetism and the needle moves proportionally--whichever direction the current flows either from gen to battery or in reverse determines charge or discharge direction.
If something happened to the regulator and the charge rate was far above the design limit of the ammeter, some damage could have been done and ammeter could have became permanently magnetized or overheated. If that were the case, I would think you would have noticed some other symptoms such as very hot components or smoke from generator or regulator. Conversely, if the regulator cutout points stuck, battery would short thru generator with the same symptoms but on the discharge side.
Old age or excess heat could have caused the phenolic support to have deformed or the ceramic supports could have broken --anything moving out of position so the needle is binding or not free to move smoothly anymore. Dried out and dirt could also be an issue. To test, I think about the only way is to have the charging system checked to make sure that is OK. If so, then substitution with a good but temporary aftermarket ammeter would tell the tale. Here is a picture of a slightly different 41 ammeter and the 47 both showing the phenolic support plate plus a diagram of the charging system showing how the ammeter wires in.
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If something happened to the regulator and the charge rate was far above the design limit of the ammeter, some damage could have been done and ammeter could have became permanently magnetized or overheated. If that were the case, I would think you would have noticed some other symptoms such as very hot components or smoke from generator or regulator. Conversely, if the regulator cutout points stuck, battery would short thru generator with the same symptoms but on the discharge side.
Old age or excess heat could have caused the phenolic support to have deformed or the ceramic supports could have broken --anything moving out of position so the needle is binding or not free to move smoothly anymore. Dried out and dirt could also be an issue. To test, I think about the only way is to have the charging system checked to make sure that is OK. If so, then substitution with a good but temporary aftermarket ammeter would tell the tale. Here is a picture of a slightly different 41 ammeter and the 47 both showing the phenolic support plate plus a diagram of the charging system showing how the ammeter wires in.
Attach file:
(28.67 KB) (24.94 KB)
(55.55 KB)
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