Help with a B&K 1077PAL

[AlanInSitges]

Yes, I'm pretty stoked! PAL horiz frequency is pretty close to NTSC 15,625Hz, and just found what I guess is the intensity control on the cathode of the CRT - I'll lower it, good suggestion.

According to the service manual:

The horizontal oscillator provides a 15,750Hz sawtooth waveform from a multi-vibrator type circuit. An internal adjustment is provided for frequency adjustment. The output of this stage is available at the HORIZ GRID DRIVE jack for injection into television receivers. The horizontal oscillator is synchronized with a sub-multiple of the 189 KHz color bar generator.

I can't find anything resembling a frequency adjustment in the horizontal oscillator circuit - could it be something besides a potentiometer?

It seems to me that R52 and R53 are the most likely causes of the off frequency, along with C101. That's what I'll check next.

[Kevin Kuehn]

Originally Posted by AlanInSitges

Yes, I'm pretty stoked! PAL horiz frequency is pretty close to NTSC 15,625Hz, and just found what I guess is the intensity control on the cathode of the CRT - I'll lower it, good suggestion.

According to the service manual:



I can't find anything resembling a frequency adjustment in the horizontal oscillator circuit - could it be something besides a potentiometer?

It seems to me that R52 and R53 are the most likely causes of the off frequency, along with C101. That's what I'll check next.

The horizontal freq is derived by a divide by counter(CD4013) driven by the color burst oscillator. There's a trimmer cap(C100) in series with the color crystal in the grid circuit of V6A that should allow some adjustment.

Before I'd worry much about the horz frequency I'd be looking for the cause of your vertical deflection collapse. Possibly a bad cap, connection, or tube in the vertical section. Possibly even the vertical height or linearity controls.