Condensators, how to find defected units

[Rolf Halvorsen]

I have relative often seen Guzzi's with undefined trouble - and changing the condensers have been useful.

Everytime when I have a condenser (old or new) I measure the resistance. In some cases I have found condensers with failures. A new condenser shall have unlimeted resistance - while a shortened condenser will measure some resistance.

But this is not the best way of telling me that the condenser is ok. I need help.

How can I with a simple instrument measure that a condenser is ok?

Rolf

[acogoff]

    The simple test I do is with an analog (el-cheap-o) ohm meter. First ground the lead to the case to discharge any tiny residual zap. Then touch the + lead on your meter to the condenser's lead and the other to the case and there should be a slight needle jump and then back to zero. That tells me it at least holds a little charge for a small time and will probably work. There are more tests that can be done, but that is what I use- other smart people will chime in. 

[lrutt]

As I recall, all condensers are small capicators, 20 to 22 uf. A capacitor measuring DVM would do the trick. I had an article once that explained by viewing the points contacts and which side the deposits were forming on you could determine if the condenser was over or under the optimum value.

[RinkRat II]

  Greetings, Rolf
    I have a TIF Tic Tracer model300cc. It's 25+ years old but still works great. They discontinued them but you can find used ones now and again. It's used to detect voltage without contact and has a pair of leads to test capacitors, condensors and diodes.  Different sounds are emitted for different values and connections.  You can also use a volt/ohmmeter but generally on something that small it's tough unless you have an old analog meter.

    Paul B

[s1120]

As I recall, all condensers are small capicators, 20 to 22 uf. A capacitor measuring DVM would do the trick. I had an article once that explained by viewing the points contacts and which side the deposits were forming on you could determine if the condenser was over or under the optimum value.

I remember back when I went to school for this, I learned that also...  Ill be damned if I remember now though. :)      Back then we mostly just swapped when we did points...  now it seems that the new ones are so badly made...

[Muzz]

    The simple test I do is with an analog (el-cheap-o) ohm meter. First ground the lead to the case to discharge any tiny residual zap. Then touch the + lead on your meter to the condenser's lead and the other to the case and there should be a slight needle jump and then back to zero. That tells me it at least holds a little charge for a small time and will probably work. There are more tests that can be done, but that is what I use- other smart people will chime in.

This is what I do.  My biggest problem was finding another analogue one after the previous one died.  Almost all are now digital, which you can't use for this test.

On the smaller capacity condensers the flick will be very fast, the bigger capacity ones slightly slower.  However, there is a certain amount of experience needed to quantify this.  e.g., if you have a smaller capacity one that does climb back but at a slowish rate and does not return quite to infinity, then I would conclude that although it might still be working, it is on the way out.

[Rolf Halvorsen]

I have several new and old condensers lying around. Some are new and some I expected to be gone.

I did measure resistance with an analog instrument. + on the wire and - on the case.


All behaved the same way - first the needle jumped up just a little - and then returned to indefinitely resistance. Performing the measurment once more gave no jumping of the needle - but after letting the wire touch the case - and then measure once more - it behaved like the first time.

So I think now that all my condensers are ok.

A, I right?

[acogoff]

     That is the same rudimentary test I do and has seemed to be good enough to make my points equipped engines run reliably.

[Kiwi_Roy]

There are two main faults you can get with a condenser, a short or an open circuit, ether one will render them useless.
This type of capacitor doesn't have a polarity.

I have several digital meters, they all dip down in resistance then wind up to infinity over a second or two.
If you charge the capacitor one way then swap the leads over it will charge the other way.

[Guzzistaracing]

Hei Rolf.
Most modern multimeters have a condensator test function. Check your and you will probably find it.