Brand : Sony 21”

Model: KV-M2151A ch. BE2A

Schematic : eservice dot com

Fault : intermittent narrowing and widening picture

The fault crops up when the chassis is moved even slightly so I think it may be a false contact.
This Tv has an East-West correction section even if it is a 21″, so I turned my attention to this part of the chassis. On my first inspection with the magnifying lens, I did not see any dry joints.  This time it doesn’t seem to be the usual capacitor soldering problem that was connected to the coils and integrated circuit.

tvc 21 tv repair

I noticed “strange movements” on IC801 output waveform when tested with the oscilloscope; the input the sawtooth wave was normal and constant. I replaced on a trial basis the integrated IC801 (BA4558) and also Q803 (2SD1761), but no change (it was a normal transistor and an operational IC so I did not have to order the spare part).

Schematic tv sony 21"

At this point it boils down to checking resistors R806 and R808 (respectively 1Kohm and 56Kohm), two SMD resistors which form a reaction circuit, on soldering these two components I have resolved the problem. When I moved the chassis (without exaggerating obviously), there were no more intermittent narrowing and widening of picture problem.

About

I am a TV technician working in Torino Italy in collaboration with Roberto Salerno, TV technician and technical journalist and Katey Denny , English technical translater .

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