Triumph Rat Motorcycle Forums banner

1 - 7 of 7 Posts

·
Registered
Joined
·
109 Posts
Discussion Starter #1
Having a problem with getting a spark, Seems to be leading me in the direction of the capacitor. How do I go about checking it with a meter, and what should it read out too? Also Im going through and checking the diode is it supposed to read out to .5? because it reads out to .4
This 79 bonne is driving me nuts right now.
 

·
Registered
Joined
·
914 Posts
Mr S some mutimeters will read capacitance, a standard meter won't.

Which capacitor are you trying to measure?

Again which diode are you measuring and is 0.4 the forwards volt drop?

Derry.
 

·
Registered
Joined
·
3,989 Posts
If you`re measuring the resistance with a multi-meter, firstly disconnect it to any other components.
Initially, the capacitor will read low and then high.
The reason is: if the capacitor is discharged, it will draw current from the meter battery, charging the capacitor to the battery voltage.
This is what gives the swing on the read-out.
The speed of this `swing` is dependent on the capacitance and the series impedence. T=0.7CR...very fast normally.
This is not an indication that the capacitor is OK, for several reasons.
Working Voltage, temperature, leaks, etc. Of course if its a short circuit, throw it away.
They are used to pass AC voltages and block/maintain DC.

WRT the diode, measuring the resistance--it should read low in one direction and by reversing the leads, high the other way.
The forward Voltage across it, depends on the semiconductor material. Germanium ~0.2V...silicon~0.7V...selenium more, for single items (saturated). The old selenium types were stacks of several.
These are used to pass voltages of one polarity, and block voltages of the other polarity.
 

·
Premium Member
Joined
·
2,895 Posts
As DerryUK rightfully said a lot of multimeters won't read capacitance. However if you have an old needle type multimeter you should be able to check if the capacitor is charging connect the capacitor to a battery for a second (almost any battery will do) and then connect the multimeter. You should see a kick from the needle.
I assume you are talking about the condensor for the ignition system, you could save yourself the time and just go and buy another condensor to do a swap to test, they're not very expensive.

Webby
 

·
Registered
Joined
·
109 Posts
Discussion Starter #6
The capacitor i dont knonw which on it is, the one in my bike and the one in the book are different. Should it say right on it?
 

·
Registered
Joined
·
46 Posts
Hi Mr.
Does your bike have points?
Remove the cover on the right hand
case and check(the small round cover)
Or take a photo of the component you are
wanting to test and post it here.
Jeri
 
1 - 7 of 7 Posts
Top