Superb Blue Ring Tester

Designed By John Bachman

This Blue Ring Tester is a MUST for you to accurately test windings/coils in the electronic troubleshooting and repairing field!

blue ring tester

 The Blue Ring Tester


Click here to read the Fantastic Blue Ring Tester Article

If you use an ohmmeter or even an inductance meter to test a coil/winding then chances is very high you will not be able to repair the equipement. Why? Because both testers could misled you into believeing that the coil/winding is good where in fact the coil/winding is shorted internally between windings! Some technicians just call it as shorted turns in the winding.Your precious time will be wasted because you could not effectively locate the bad component (which is the coils). Now thanks to this simple yet a powerful tester to really test out the coils/windings that have shorted turns.


This ring tester is an inexpensive and effective way to test any high Q inductive component. It is especially useful for doing a quick check on flyback transformers, Monitor B+ coil, Ballast choke and other high frequency inductive components like deflection yoke windings and SMPS transformers. I have personally tested all the coils mentioned above and the result was fantastic! The LEDs on the left side show the Q of the device being tested, more lights or green lights = higher Q (good) and no lights or red lights = bad or low Q (short circuit), yellow lights or medium=marginal and you need to compare with a good coil. Below are the results of testing the coils/primary winding found in a CRT Monitor :


blue ring meter



 A good 15" CRT Flyback transformer primary winding

Full LED's lit (green light)


 A Bad 15" CRT Flyback Transformer primary winding

Only Two LED's lit (red light)


 A good SMPS transformer primary winding of a 14" CRT Monitor

Six LED's lit (green light) Note: Some good SMPS transformer could only lit up four to five LED's



  A bad SMPS transformer primary winding of a 14" CRT Monitor

LED's totally off (indicating a heavy short circuit between windings



 A good 15" CRT Monitor B+ coil

Full LED's lit (green light). Note: Some good B+ coil could only lit up three to four LED's


 A bad 15" CRT Monitor B+ coil

LED's totally off (indicating a heavy short circuit between windings


 A good 15" CRT Horizontal Yoke coil

Seven LED's lit (green light)


  A bad 15" CRT Horizontal Yoke coil

Only Two LED's lit (red light) indicating a partial short circuit in yoke coil winding





For the above test result you can take it as a reference or guidance. You must take note that different equipment have different type of coils/windings and the result may different from above! 




Another good reason you should get this blue ring tester is that it have the capability to perform in circuit test if you are familiar with the equipment you are repairing and this will surely save your time without having to remove coils from the circuit. Otherwise you just have to solder out one leg to test the coil. The test leads are non-polarized-that means you can test the coils using either way from the test probes.


Real Life Testimonial




  • Types of coils can be measure: Flyback transformer, Horizontal yoke coil, B+ coil, SMPS primary winding, Fluorescent ballast/choke, and any other type of coils that have bigger inductance value of .3 microhenry and above. 
  • Comes with test leads/alligator clips 
  • 8 LED's of Red, Yellow and Green to indicate bad, marginal and good. 
  • Power supply : 9 volt battery (not included). 
  • Controls: Single push button for power on/off. 
  • Dimensions: 5.75x3.5x1 inches (147x86x24mm). 



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