Monday, March 3, 2014

Ring tester

 In my Electronic repair job I found normal multimeter is somewhat limited  in certain area. so special tools
are needed for saving  a lot of time  Ring tester is one of this kind .helping me to check small hi Q inductors SMPS transformer, TV Deflection coils ,LOT ,line driver transformer and almost any inductor working on hi frequency.Normal multimeter can only identify a open coil ,but not a shorted windings.
 I found some commercial available ring tester. but it is not available in local shops of my area.also it seems priced high. So  I decided to make a ring tester of my own.
Below is the one I successfully made from the junk box components. I found it very useful. and now it is one of my best test tool collection. Two Ic's, few LED's ,one plastic container and few resistors  made this wonderful tool. If we test it with primary of SMPS transformer or LOT windings of a good one shows all its LEDs will light. depending on the inductive reactantce  the number of LED 's light up. If any short in the windings shows all LEDs off. Any short in secondary side cause all LED OFF except the last one.we can test these transformer without take apart from the board

4 comments:

  1. This little instrument identifies faults in horizontal output stages by doing a 'ring' test, i.e. it applies pulses to the LOPT / FBT primary circuit, and counts the number of damped oscillations or 'rings' produced. For each 'ring' down to about 15% of the test pulse amplitude, one LED in the 'bargraph' lights up... nearly all faults will greatly reduce the number of 'rings' and give a very low reading.

    It can be used on both monitors and TVs because it's not frequency-sensitive, and the test signal amplitude is only 650mV- low enough not to forward-bias semiconductors in the circuit.

    To do a basic test, you connect the test leads between chassis and the HOT collector... if more than 4 LEDs illuminate, the horizontal output stage is probably OK. It can check LOPTs / FBTs out of circuit if broken-down components prevent an in-circuit test.

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  2. Have you used mylar capacitor ? Instead of MKT capacitor Sir....??

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  3. MKT Capacitor not available in local market so used mylar .but it works

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  4. thank you for your reply Sir, I have successfully made the tester and it works great in testing some transformers, but I have a question


    1. What do you mean about Horizontal output stage Sir? Is it the whole circuit in the horizontal section? Or Not?

    2. How to use this tester to test yoke coil? Where should I connect the test leads ? for me to identify whether the yoke coil is still good or bad? Thank you Sir.

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