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-   -   29 Tudor charging system question (https://www.fordbarn.com/forum/showthread.php?t=282381)

fred93 06-10-2020 05:01 PM

29 Tudor charging system question
 

Finishing the 29 Tudor.

Today I started the engine and I noticed that the ammeter just stayed at zero. So I turned on the headlights so see if the ammeter moved--it didn't move at all.

The ammeter is new (probably only has a couple hours of running time). The ammeter has always shown a charge with the engine running but today it shows nothing-just sits at zero. I turned off the engine and turned on the headlights again--nothing-still zero. I gave it a gentle tap--nothing!

I started the engine again and took a voltage reading at the battery--6.65 volts. I took a reading at the generator output wire and it read 7.94 to 8.00 volts. I took another reading at the output post of the cutout--it read 6.65 volts.

I assume that the cutout is not working. It is also new (diode type) . (I had a fellow that worked at my auto repair shop and his quote was "New means NOT tested")

Can I bypass the cutout with a jumper wire-as a test to see if the cutout is bad? or do I need to just replace the cutout?

Jim/GA 06-10-2020 05:14 PM

Re: 29 Tudor charging system question
 

If the ammeter needle does NOT move when you turn on the headlights, as I think I understand from you, the ammeter is not connected properly or the ammeter is defective.

Start there.

The diode cutout might also be bad, but you need to get the ammeter working first.

Trace the wires from the generator to the terminal box to the ammeter to the terminal box to the starter switch. Something in there is not right.

When you turn the headlight switch on, do the lights light up? If so, the headlight switch is getting power from somewhere. If not, that's why the ammeter needle is not moving.

If wired correctly, the ammeter might just be defective. Is it an original or a reproduction? The repro ammeters are notorious for being defective.

:cool:

MVal 06-10-2020 05:18 PM

Re: 29 Tudor charging system question
 

Had the exact same thing happen to me yesterday--I just hit the ammeter with the palm of my hand forcefully a couple of times and bingo--everything worked. This has happened to me a few times so know the routine for my setup.

fred93 06-10-2020 05:29 PM

Re: 29 Tudor charging system question
 

Quote:

Originally Posted by Jim/GA (Post 1897760)
If the ammeter needle does NOT move when you turn on the headlights, as I think I understand from you, the ammeter is not connected properly or the ammeter is defective.

Start there.

The diode cutout might also be bad, but you need to get the ammeter working first.

Trace the wires from the generator to the terminal box to the ammeter to the terminal box to the starter switch. Something in there is not right.

When you turn the headlight switch on, do the lights light up? If so, the headlight switch is getting power from somewhere. If not, that's why the ammeter needle is not moving.

If wired correctly, the ammeter might just be defective. Is it an original or a reproduction? The repro ammeters are notorious for being defective.

:cool:


Everything worked fine until today. The ammeter always showed a charge with the engine running at high idle.

When the engine was not running the ammeter always showed a discharge when I turned on the headlights.

The ammeter is a new repro.

The cutout is a new diode type.

Both have been on the car for at least three years BUT they have only a few hours of run time on them.

Jim/GA 06-10-2020 05:55 PM

Re: 29 Tudor charging system question
 

I suspect the ammeter is defective. Highest probability explanation. Start there.

.

Kurt in NJ 06-10-2020 06:03 PM

Re: 29 Tudor charging system question
 

A diode cutout looses about 1/2 volt going through it,

fred93 06-10-2020 07:55 PM

Re: 29 Tudor charging system question
 

Quote:

Originally Posted by Kurt in NJ (Post 1897786)
A diode cutout looses about 1/2 volt going through it,

Maybe I was not clear on my details.

With the engine running and using a Fluke meter I get 8.00 volts going into the cutout and only 6.5 volts coming out of the cutout. (actually the 6.5 volts is just what the battery is providing)

That seems to me that the cutout is not letting current go through the cutout.

Can I bypass the cutout with a jumper wire to test the ammeter?

Jim/GA 06-10-2020 08:37 PM

Re: 29 Tudor charging system question
 

Quote:

Originally Posted by fred93 (Post 1897813)
Maybe I was not clear on my details.

With the engine running and using a Fluke meter I get 8.00 volts going into the cutout and only 6.5 volts coming out of the cutout. (actually the 6.5 volts is just what the battery is providing)

That seems to me that the cutout is not letting current go through the cutout.

Can I bypass the cutout with a jumper wire to test the ammeter?

Sure! As a temporary test; don't leave it connected. Have the RPM up high enough that you get the 8 volts, touch the wire on there.

Bill G 06-11-2020 12:26 AM

Re: 29 Tudor charging system question
 

Interesting, but even if the generator and the cut-out were totally defective, you should still get a discharge reading on the ammeter when the lights are on whether the engine is running or not. That still points to an ammeter issue in my opinion.

Benson 06-11-2020 08:47 AM

Re: 29 Tudor charging system question
 

7b0

Chuck Sea/Tac 06-11-2020 07:02 PM

Re: 29 Tudor charging system question
 

The amp meter is not dependent on the voltage regulator/cut out to show a discharge. If it isn’t moving then you have a wire loose or it’s defective. The cut out working or not working changes the readout of the amp meter, but you will still have a readout regardless of whether the cut out is open or closed.

fred93 06-12-2020 11:17 AM

Re: 29 Tudor charging system question
 

1 Attachment(s)
Quote:

Originally Posted by Chuck Sea/Tac (Post 1898180)
The amp meter is not dependent on the voltage regulator/cut out to show a discharge. If it isnít moving then you have a wire loose or itís defective. The cut out working or not working changes the readout of the amp meter, but you will still have a readout regardless of whether the cut out is open or closed.

I can't believe that so many of the parts that I have bought for this car have turned out to be junk.

I sent all the shocks out to Robert Paul years ago and the two front shocks started leaking after several years of just sitting in the garage. (I don't know what I am going to do about that problem yet)

I purchased two new hood shelves from Bratton's that did not fit (they refunded me on those). And I bought new ones from Bert's that do fit.

The floor mats that I bought from Bratton's did not fit--they refunded me on that--I finally got a good set from Snyder's.

I went through several pieces of new window glass from Bert's--they had bad scratches on the glass--Bert's worked with me on those and I finally got a good set.

I bought brand new authentic cooling hose clamps that are not worth a s**t. I found some really good ones at a plumbing store.

I bought a brand new fuel sediment bulb that leaks like a sieve--I removed the screen to elevate that problem and installed an aftermarket filter inside the glass bulb

Now I have a bad cutout AND a bad (presumably) ammeter! Both items were purchased several years ago but they only have a few hours of run time on them!

For test purposes I disconnected the wire coming from the generator to the cutout and placed a jumper wire from that wire to the wires that are attached to the output side of the cutout--please see photo for more clarity. With the engine running at high idle and the jumper wire in place, I then have 7.97 volts going into the battery. However, the ammeter still did not move off of zero.

Correct me if I am wrong---since the headlights and dash light is working then the ammeter is not fried??? but it is just not working???

I read somewhere that the ammeter is somewhat like a fuse--if too much current is going through it, it will just burn out???

ryanheacox 06-12-2020 01:03 PM

Re: 29 Tudor charging system question
 

Quote:

Originally Posted by fred93 (Post 1898362)
Correct me if I am wrong---since the headlights and dash light is working then the ammeter is not fried??? but it is just not working???

I read somewhere that the ammeter is somewhat like a fuse--if too much current is going through it, it will just burn out???


Correct, not fried and not working. Almost all of the current going through the ammeter is going through a shunt. A small amount goes through a fine winding between two magnets which will swing the needle either way. That winding could have fried, broken or who knows. The new ammeters really are junk. It's probably just as accurate with the needle at 0 as it was when it was moving.


As far as the bad cutout... yep I've got one too except if failed closed, acted just like your jumper. Was a new in box diode cutout... oh well.

fred93 06-12-2020 01:46 PM

Re: 29 Tudor charging system question
 

Quote:

Originally Posted by ryanheacox (Post 1898383)
Correct, not fried and not working. Almost all of the current going through the ammeter is going through a shunt. A small amount goes through a fine winding between two magnets which will swing the needle either way. That winding could have fried, broken or who knows. The new ammeters really are junk. It's probably just as accurate with the needle at 0 as it was when it was moving.


As far as the bad cutout... yep I've got one too except if failed closed, acted just like your jumper. Was a new in box diode cutout... oh well.

+++++++++++++++++++++++++++++++++++++++
So where do I go to buy a GOOD ammeter and a GOOD cutout?

If everything is junk are we all just screwed??

ryanheacox 06-12-2020 02:17 PM

Re: 29 Tudor charging system question
 

I would call Bert's and see if Steve has good used parts. I'm sure he has good cutouts both new and used. I think ammeters are a hot commodity though. I think most of the vendors pulled their stock... they were just that bad. Could also post a wanted ad here.

chrs1961815 06-12-2020 03:28 PM

Re: 29 Tudor charging system question
 

You have to get an original ammeter - the repros have been junk for many years. Not too much goes wrong with originals - there is basically just a magnet inside with a pointer on it that is very fragile.

Bill G 06-12-2020 05:32 PM

Re: 29 Tudor charging system question
 

A person can easily run the car without one. A jumper across the two posts on the junction box will bypass the ammeter and get you on your way.

fred93 06-12-2020 06:21 PM

Re: 29 Tudor charging system question
 

4 Attachment(s)
Quote:

Originally Posted by ryanheacox (Post 1898396)
I would call Bert's and see if Steve has good used parts. I'm sure he has good cutouts both new and used. I think ammeters are a hot commodity though. I think most of the vendors pulled their stock... they were just that bad. Could also post a wanted ad here.

+++++++++++++++++++++++++++++++++++++++++
I don't know if this is an original or not. It works--I replaced it because it looks bad. See photos.

Any thoughts from anyone if it is original???

I may just make one out of the two!

Just not looking forward to taking the dash panel apart.

fred93 06-12-2020 06:30 PM

Re: 29 Tudor charging system question
 

Quote:

Originally Posted by ryanheacox (Post 1898396)
I would call Bert's and see if Steve has good used parts. I'm sure he has good cutouts both new and used. I think ammeters are a hot commodity though. I think most of the vendors pulled their stock... they were just that bad. Could also post a wanted ad here.

+++++++++++++++++++++++++++++++++++++++

Are the diode cutouts junk?

Back in the 60's when I first started working on A's the cutout would stick closed and you had a dead battery. I thought that the diode would alleviate that problem!

I may have an older cutout, but I doubt it is original--but i know it is not a diode type.

chrs1961815 06-12-2020 06:55 PM

Re: 29 Tudor charging system question
 

That ammeter looks original from what I can tell. Or it might be a very old reproduction. Either way it looks pretty good and it will work better than the one you currently have.


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