Hello.
I'm new here, and to be honest I dont know a lot about electronics. More than most pedestrians, but much less than I need to know. Thats slowly changing as I'm currently schooling myself up.
I'm trying to diagnose an ECU fault in my 89 Celsior / Lexus. I'm told that the Electrolytic caps in that ECU are prone to fail and that they can be tested in circuit to see if they are failing. I have just purchased myself a cheap ESR meter but when looking for a chart to see what the ESR values should be I seem to be finding lots of different figures.
For example, one chart says that a 4.7uF 25V e-cap should be 6ohms and another says the same e-cap should be 2ohms
charts obtained via google search for "ESR Chart".
I'm confused. My understanding is the lower the value the better, but why the difference in charts? Is it dependant on manufacturer? I realised that some manufactures produce better quality caps than others... is that the reason for the difference?
Can someone point me to a reliable chart or do I need to go to the manufacturers for their charts (if they release them)?
e-caps I'm looking to test are apparently Nichicon's PF(M) type capacitors. These have very low ESR but contain quaternary ammonium compounds. Hence hey have a life span of about 10-15 years then fail and often leak potentially destroying the circuit board. Fortunately mine have not leaked (yet).
I'll be replaceing them with "United Chemi-con" e-caps. These are also apparently low ESR but dont contain the corrosive quaternary ammonium compounds.
Anyway, need a chart to see what my old caps and my new ones look like. I dont know enough to know whats right and wrong here and didnt even know that there was another value of consequence when it comes to caps (ESR).
Thanks for reading all this and giving a noob a chance.
Note: ECU = Engine Control Unit = Small computer that controls the Engine, has very tight electrical tolerances.
I'm new here, and to be honest I dont know a lot about electronics. More than most pedestrians, but much less than I need to know. Thats slowly changing as I'm currently schooling myself up.
I'm trying to diagnose an ECU fault in my 89 Celsior / Lexus. I'm told that the Electrolytic caps in that ECU are prone to fail and that they can be tested in circuit to see if they are failing. I have just purchased myself a cheap ESR meter but when looking for a chart to see what the ESR values should be I seem to be finding lots of different figures.
For example, one chart says that a 4.7uF 25V e-cap should be 6ohms and another says the same e-cap should be 2ohms
charts obtained via google search for "ESR Chart".
I'm confused. My understanding is the lower the value the better, but why the difference in charts? Is it dependant on manufacturer? I realised that some manufactures produce better quality caps than others... is that the reason for the difference?
Can someone point me to a reliable chart or do I need to go to the manufacturers for their charts (if they release them)?
e-caps I'm looking to test are apparently Nichicon's PF(M) type capacitors. These have very low ESR but contain quaternary ammonium compounds. Hence hey have a life span of about 10-15 years then fail and often leak potentially destroying the circuit board. Fortunately mine have not leaked (yet).
I'll be replaceing them with "United Chemi-con" e-caps. These are also apparently low ESR but dont contain the corrosive quaternary ammonium compounds.
Anyway, need a chart to see what my old caps and my new ones look like. I dont know enough to know whats right and wrong here and didnt even know that there was another value of consequence when it comes to caps (ESR).
Thanks for reading all this and giving a noob a chance.
Note: ECU = Engine Control Unit = Small computer that controls the Engine, has very tight electrical tolerances.