Hickok Color Bars

[NoPegs]

Originally Posted by old_tv_nut

Did you ever get a 315 kHz crystal? I think it should be feasible to break the feedback path of the oscillator and install a 555 timer oscillator to drive the grid if you can't get a crystal.

Possibly more accurate to get a 31.5khz crystal and use a PLL to scale it x10. The 555 has way too much drift to be used in this kind of application.

[old_tv_nut]

Originally Posted by NoPegs

Possibly more accurate to get a 31.5khz crystal and use a PLL to scale it x10. The 555 has way too much drift to be used in this kind of application.

Certainly not as good as a crystal, but: to use the color bar function (as opposed to using the generator for a sweep frequency reference) this app needs +/- 1% max tolerance - it's only affecting the H and V frequencies, not the color. The 555 chip itself has a freq tempco of about 90 ppm per deg C. , so I think it would be feasible with a polystyrene cap and small trimpot. Even if it did drift a little too much, you could just turn the pot until the TV set syncs.

Not saying it's elegant, just a way to run without a crystal.

[Tomcomm]

MY previous entry indicated the Hickok 655 is producing a marginally acceptable color bar pattern on both the 21CT55 and Sony. However the color bar waveforms indicate a total mess! The Hickok 655 has 19 pots and 6 switches that I "adjusted" by intuition. What is needed is the official Hickok 655 initial setup procedure. Surly this document must exist somewhere possible included in the instruction manual or in some member's memory? Anyone attempting a precise alignment of the two wideband RCA CTC2 CTC100 and CTC2B 21CT55 must be aware that precise setup of the color matrix requires a bar generator having both Q and I bars for the CT100 and both Q and B-Y bars for the 21CT55! Both RCA and SAMS procedures insist on using bar generators that provide 100% saturated R-Y, B-Y, "Q" and "I" video signals. The RCA WR-61A and the Hickok 600 series would be exceptable.
So, any suggestions how I can obtain this information would be appreciated.