вроде инверсия синхросигнала (для некоторых телевизоров)

"There are/were a number of television video systems around the world, some use positive sync signals and some use negative sync signals. Same as in some television video systems, the video signal is a positive going voltage for peak white, while in others, positive is total black. So R36, R37, C3 and TR1 may have been provided to allow for one of these other television video systems."