HP8563E-CPU Clock,Line generator circuits and blanking control - UK Vintage Radio Repair and Restoration Discussion Forum

djsbriscoe · 28th Jun 2022, 11:09 pm

I'm trying to understand how the Simmconn Labs Newscope 6 VGA display kit I have just finished installing interfaces with the A2 board (processor board) on my HP8563E Spectrum Analyser.
The original problem of having no working display still persists, however. The installed kit works fine. It's just that the kit's PCB is probably (I have not confirmed this with actual testing yet) not receiving the digital signals from the line generator circuits etc on the A2 board.
It appears that the CPU is not working at all. I have put a scope probe on pin 15 of the CPU. It does NOT show a nice clean 16MHz square wave like I was expecting. I will have to investigate further.
It appears that the CPU clock is derived from a 16 MHz Phase locked Loop which in turn is generated from a 10MHz Oven controlled Crystal oscillator. So something along this chain may not be working.
Am I also correct in assuming that the line generator DACS convert digital data into an analogue voltage that moves the electron beam in the CRT(not used now the Newscope6 is fitted)? How does the blanking control play its part? And I'm assuming that the Z axis is really just brightness of the trace? Is a vector display similar to just painting very small lines very quickly all over the screen?
Anyway, at least nothing has gone up in smoke so far, so progress IS being made VERY slowly. I just hope I'm beginning to understand how some of it works.

Radio Wrangler · 28th Jun 2022, 11:39 pm

The vector display really is the drawing of lots of lines all over the screen. Analogue circuitry allows lines of different lengths to be drawn at different speeds, making the brightness the same irrespective of line length.

Blanking is used to completely extinguish the beam as it is moved from one line to the next in its sequence, if the end of one line is not at the same coordinate pair as the start of the next line.

Z-mod allows different intensities to be drawn, so the trace is brighter than the graticule, and that a couple of different intensities oof characters can be used to show active parameter fields as well as normal ones and semi-hidden ones as it's equivalent to 'greyed out'

David

28th Jun 2022, 11:09 pm	#1
djsbriscoe Pentode Join Date: May 2015 Location: Hemel Hempstead, Hertfordshire, UK. Posts: 133	HP8563E-CPU Clock,Line generator circuits and blanking control I'm trying to understand how the Simmconn Labs Newscope 6 VGA display kit I have just finished installing interfaces with the A2 board (processor board) on my HP8563E Spectrum Analyser. The original problem of having no working display still persists, however. The installed kit works fine. It's just that the kit's PCB is probably (I have not confirmed this with actual testing yet) not receiving the digital signals from the line generator circuits etc on the A2 board. It appears that the CPU is not working at all. I have put a scope probe on pin 15 of the CPU. It does NOT show a nice clean 16MHz square wave like I was expecting. I will have to investigate further. It appears that the CPU clock is derived from a 16 MHz Phase locked Loop which in turn is generated from a 10MHz Oven controlled Crystal oscillator. So something along this chain may not be working. Am I also correct in assuming that the line generator DACS convert digital data into an analogue voltage that moves the electron beam in the CRT(not used now the Newscope6 is fitted)? How does the blanking control play its part? And I'm assuming that the Z axis is really just brightness of the trace? Is a vector display similar to just painting very small lines very quickly all over the screen? Anyway, at least nothing has gone up in smoke so far, so progress IS being made VERY slowly. I just hope I'm beginning to understand how some of it works.

28th Jun 2022, 11:39 pm	#2
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,901	Re: HP8563E-CPU Clock,Line generator circuits and blanking control The vector display really is the drawing of lots of lines all over the screen. Analogue circuitry allows lines of different lengths to be drawn at different speeds, making the brightness the same irrespective of line length. Blanking is used to completely extinguish the beam as it is moved from one line to the next in its sequence, if the end of one line is not at the same coordinate pair as the start of the next line. Z-mod allows different intensities to be drawn, so the trace is brighter than the graticule, and that a couple of different intensities oof characters can be used to show active parameter fields as well as normal ones and semi-hidden ones as it's equivalent to 'greyed out' David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done