Question About Blue Ring Tester
I received an email today from a member who asked about the accuracy of Blue Ring Tester in testing coils. Here is the question:
“Today I have repair a Sanyo Flat Screen Color TV which has a Pincushion problem at first i check the output transistor and check ok and second i check two pincushion coil with the blue ring tester, because the plastic which wrap around the coil has a little bit deform, but when I check it with the blue ring tester it taste bad no LED Light. the i try to replace the two coil but it the the pincushion problem is still there. Further investigation reveal that one of the signal diode was shorted and replacing the diode solve the pincushion problem.What I mean was this why the Blue ring tester cannot detect if the coil is good or bad when you always say it can detect. I had no problem with the ESR meter I agree with you but not the Blue ring tester.it cannot tell me whether if there is a short or not.Can you tell me?”
If you refer to my website at http://www.electronicrepairguide.com/blue-ring-tester.html especially on the tester specification, you would see that i mentioned four types of coils i.e B+ coil, smps primary winding, horizontal yoke coil and flyback primary winding coil. I didn’t mention the pincushion coil, horizontal size coil and horizontal linearity coil was because the inductance value were quite low. That means if the coil has a core that have only little loops (windings) in it then we cannot expect the blue ring tester to show full LED and etc. If the inductance value is low we can only expect low or no LED lit. If the inductance value is high then we can expect it to register some reading of LED lit. In other words, the higher the inductance value of a coil, the higher LED of the Blue Ring Tester will light up. A high inductance value coil that have shorted turns will cause the LED light to go low or no light at all.