Tektronix 4051 repair.

I cannot find anything mentioned about character blanking in the circuit description. I read this on the topic "Alphanumeric Display": "Refer to the display control block diagram (Fig 6-13). The display coordinate position is generated through the digital-to-analog converters (X DAC and Y DAC) and fed through the filter circuitry with the filtering disabled. A short time later, either SOT is activated to print a cursor refresh dot or ADOT is activated to print a character dot. The timers for cursor intensity and character intensity are adjustable by potentiometers accessible through the bottom of the assembled instrument." Maybe this is the "A short time later" that it is not working since seems to draw instantly. But as far as In understand that timer is generated in the digital parts. Note that this is not a computer or terminal. It is an instrument per Tektronix definition... Unfortunately the detailedness of the circuit description is not up to the DEC standards in my opinion. There are no scope diagrams describing the pulses going to the Z-axis as far as I can see which is unfortunate. /Mattis