LM1889N Composite Video?

[jpagen]

Hi

After recapping my BBC B and Acorn A3000(usual battery damage) with help from Stardot, I have been trying to repair my childhood Videomaster Star Chess game.https://retroordenadoresorty-blogspot-c ... _tr_pto=sc

I re-tuned to the analogue RF signal on an old TV (which I know used to work with the console), I can just about see a garbled picture (black and white only). Sound is working fine through the console speaker.

The console has an LM1889N IC https://pdf1.alldatasheet.com/datasheet ... 1889N.html in the top right and I thought it may be possible to pull a composite signal from this(assuming the fault is later in the circuit). I would be happy with black and white to start with but this is way beyond my knowledge. Does anyone know if this would be possible and how I may go about it?

I tried replacing the LM1889N but that made no difference.

Appreciate any help!

[1024MAK]

Would need the schematic circuit diagram, as there are a number of configurations for the LM1889N. It has different sections that can be used differently depending on the requirements.

Mark

[jpagen]

Would need the schematic circuit diagram, as there are a number of configurations for the LM1889N. It has different sections that can be used differently depending on the requirements.

Mark

OK thanks for responding. There does not appear to be any circuit diagrams already so I would need to start from scratch. It is only a single sided PCB but there is a soldered shield which I will need to remove. I will need to find some suitable circuit diagram apps....there seem to be quite a few for Linux but will take me some time to plot out the whole circuit board!

[1024MAK]

For Linux, for making schematics I use gschem, part of gEDA (link). It does take a little getting used to. But once you have the hang of it, it's quite quick and easy.

Although when reverse engineering, I draw on paper using a propelling pencil, but with the chips drawn in pen.

Only when I'm happy that I have recorded the circuit correctly do I redraw in in gschem.

Mark

[jpagen]

For Linux, for making schematics I use gschem, part of gEDA (link). It does take a little getting used to. But once you have the hang of it, it's quite quick and easy.

Although when reverse engineering, I draw on paper using a propelling pencil, but with the chips drawn in pen.

Only when I'm happy that I have recorded the circuit correctly do I redraw in in gschem.

Mark

Thanks for the link and advice. This will take some time!