Condensor tester

R

russcc

Well-known member
I was at Ray Helger's Antique Parts today, and he had a real simple condenser tester which you really need if you buy any of the repop crap. Ray only has NOS or NORS, but still he checks them before he sells them anyway. Anyone have a schematic for it they wouldn't mind sharing. Looked like a simple, old circuit board with some resistors and other parts.
Thank you Fordbarners
 
You need to heat old condensers to make sure the work. Heat with a heat gun until you can only hold between two fingers for 2 to 3 seconds with worn ruff fingers, tender fingers are a quick drop. We are talking in the 140 to 150 degree range. Most will work good cold but leak and don't hold a charge when hot having the same effect bad as a coil. Use a analog volt meter, the kind with a needle. Put it in a high ohm range and touch one lead to the body and the other to the lead or terminal. Reverse the leads and each time reversed the small battery voltage from the meter charges the condenser. you will see the needle jump up a half inch or so and slowly bleed down. If it works the same when heated up you have a good condenser. G.M.
 
I have not seen the circuitry you are talking about. I have a Fluke digital multimeter that has a cap tester. Easy to clip the leads on the cap then heat it up and see if it's value changes.
 
Using an ohm meter to test a condenser will indicate whether it's totally dead or actually does something but not it's actual capacitance which should be between .2 and .3 mF (200-300 nF) .25 mF is the ideal goal. As gearhead1952 said, better to use a meter that actually measures capacitance such as this one I got from Radio Shack. I take it with me to NAPA when I go to buy their condensers to test them out before buying them. When I went just recently I tested several that were close to specs but not quite there before finding one that was. (The one pictured is slightly over specs. The meter is showing nanofarads.)

IMG_3716.jpg


For more about why the actual capacitance is critical for the health of the points read here: http://www.farmallcub.com/phpBB2/viewtopic.php?f=11&t=38576

Here is a picture of one of my contact points showing the transfer of metal discussed in the article if the capacitance of the condenser too high.

IMG_3722_zpsca530843.jpg
 
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The old capacitor testers also check for leakage. It can have the correct capacity but how long will it hold the charge. This is where the heat make a difference.
 
G.M. said:
You need to heat old condensers to make sure the work. Heat with a heat gun until you can only hold between two fingers for 2 to 3 seconds with worn ruff fingers, tender fingers are a quick drop. We are talking in the 140 to 150 degree range. Most will work good cold but leak and don't hold a charge when hot having the same effect bad as a coil. Use a analog volt meter, the kind with a needle. Put it in a high ohm range and touch one lead to the body and the other to the lead or terminal. Reverse the leads and each time reversed the small battery voltage from the meter charges the condenser. you will see the needle jump up a half inch or so and slowly bleed down. If it works the same when heated up you have a good condenser. G.M.
Click to expand...
Hey GM, where do you get a Analog volt meter with a Batt in it? I've got a couple of old car hot rod volt meters but that's not the answer, My test meters are all digital. Walt
 
Walt Dupont--Me. said:
Hey GM, where do you get a Analog volt meter with a Batt in it? I've got a couple of old car hot rod volt meters but that's not the answer, My test meters are all digital. Walt
Click to expand...

Digital meters are a fairly 'new-fangled" gadget. They have only been made since 1955.:eek: Some are a little hesitant to modernize their equipment.
 
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Some won't hold even a nano second. It will leak to the case as soon as the charge builds to the point it can jump the insulation if the insulation is bad.

Most of the old testers were analog and they worked just fine. It might be hard to find the batteries though.
 
Walt Dupont--Me. said:
Hey GM, where do you get a Analog volt meter with a Batt in it? I've got a couple of old car hot rod volt meters but that's not the answer, My test meters are all digital. Walt
Click to expand...

Walt,
On ebay there are hundreds of them.
The Simpson 260 was/is one of the more popular ones. They use a standard D cell for two of the ohm ranges.
I got 289 hits for it.
 
When in high school I used to hold a condenser against the engine head and the pigtail against the spark plug to charge it up, put it very carefuly back in the box and give to a buddy to look at. I once gave one to my Physics Teacher. It is good thing that he was a good sport. They will hold a charge for quite a while.
 
With the build up on the points contact,some where there is some info on which side of the points the build up is on tells you wether the condensor it too high or low capacity.
Lawrie
 
Lawrie said:
With the build up on the points contact,some where there is some info on which side of the points the build up is on tells you wether the condensor it too high or low capacity.
Lawrie
Click to expand...

That's the link I put in post # 4. http://www.farmallcub.com/phpBB2/viewtopic.php?f=11&t=38576

From that article: "A condenser with too much storage or capacitance will cause a build up (metal transfer) on the mounting side of the points. While a condenser with not enough storage or capacitance will cause a build up (metal transfer) on the arm side of the points. Sometimes the right sized condenser will end up in your ignition system and no transfer will occur. . . Look for the metal transfer. If there is none consider not replacing the condenser as it is matched to your particular ignition system. If there is metal transfer replace the condenser as you have nothing to lose in the process."
 
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