. Various k7205 - In-circuit LOPT-FBT Tester free download

File name k7205 - In-circuit LOPT-FBT Tester.pdf

Assembly Manual In-circuit LOPT/FBT Cat No. K 7205 Tester by Bob Parker PROJECT INFORMATION SUPPLIED BY ELECTRONICS AUSTRALIA - August 1998 Issue ACN 000 908 716 WEBSITE: E-MAIL: www.electronicsaustralia.com.au [email protected] Please read Disclaimer carefully as we can only guarantee parts and not the labour content you provide. K I T Here's the design for a low cost, easy to build and use battery operated `shorted turns' tester for line-output or `flyback' transformers, and other HF wound components like deflection yoke wind- ings and SMPS transformers. Tests have shown it capable of finding at least 80% of LOPT/FBT faults, so it can save a lot of time and trouble. Small and rugged, it's well worth a place in the toolk- it of anyone involved in servicing TV receivers, video monitors and computer power supplies. f you're reading this, then chances are tension (EHT) supply of around 25 kilo- However the failure which service I that you're a TV and/or computer mon- itor repair technician - who doesn't need volts for the final anode circuit of the cathode ray tube. It's also possible the technicians dread is a shorted winding in the LOPT itself. Unfortunately LOPTs to be told that horizontal output stage HOT has failed simply from old age or tend to be specifically designed for the faults cause more than their fair share of overheating due to unevenly- make and model of the TV or monitor headaches! Operating at high voltages, applied/solidified heatsink compound. they are used in, which can mean a lot of frequencies and power levels, many Another occasional culprit is an insula- hunting around for a replacement. In components in this part of the circuit are tion breakdown in the deflection yoke's addition they are hardly ever cheap, and highly stressed, and failures are not only horizontal winding. not always physically easy to replace. common but their cause is often hard to In short the LOPT is not a component identify. which is easy to test by substitution, and The usual symptom of a major hori-