tv trouble shooting four(vertical collapse)

this subject is geared to analog crt types. vertical collapse can accure from transistors to caps and resistors.my experance is most vert drop or fold over is cause by capacitors most of the time.know watch me here i have seen in rca ctc203 zenith 24 inch that had a vert fold over or a partical drop cause a capacitor over near flyback b-plus supply to the trippler.because its part of b=plus.so the point is that vertical problems can be caused by caps in other parts of the tv.so the rule here is if a cap is lets say for conversation is 4.7uf but at 350vdc chances are its going to be a cap with low value high voltage rating. because and cap in a b-plus circuit is going to cook and dry out and pop this includes the caps in the vertical circuit.i have notice this over my 28 years and just ran into it my self last week may fifth 08.another common failure is output transistor circuit.if you look at the print push pull is simular to a power amp npn and pnp transistors.i have notice that on a couple of repairs tv vert was pulled up from the bottom i replaced pnp negitive going transistor pulls up the bottom i removed npn to if oppsite happen down from top and it was true.so if you see this i just gave you tech a useful clue.in the U.S. we scan vertical 525 lines standard scan.but at 262.5 at a time odd number line first even line on the second scan.we sync this circuit on are 110 volt ac at 60 cycles 30 cycles for odd 30 for even lines.i mention this because when i explain how vcr heads scan you will see the comparson head speed to emulate 60cycle sync this is a subject for another editioral. clue vcr heads rotate at 29.5 rpm times two heads can you see where were going just like a tv program stay tuned.

Post edited by: hobbist, at: 2008/05/06 19:03



ok so first look for discolor components examnation of the circuit board for discoloration top and bottom look for caps in vertical and the b-plus circuit in flyback area for leaking diaelectric dome on top of caps.check forward bias on diodes (diodes are gates read in one direction only except zenier diodes will explain in later editiorals on voltage regulation.)if I.C you have dought if its good or bad change it any.transistors can be check with a checker.with this info you should be able to fix a vertical problem.

Post edited by: hobbist, at: 2008/05/06 20:13

Post edited by: hobbist, at: 2008/06/05 18:37