CPC464 Green screening

[ArvaVolente]

Hey all,

I'm a major n00b here. But I was raiding (cleaning) my parents attic for them and found my older brother's CPC464. I took it down, hooked it up and played me a shed load of "Oh Mummy" and "Galactic Plague". Was brilliant.

But unfortunately, the next day I turned it on again and got a green screen. Sometimes it would appear to turn on with lines on it. But mostly green.

Any help would be great. I would love to get this up and running again and using it.

Dermot.

[Bryce]

Need a bit more info:

- What's it connected to? Is it a green monitor by any chance? Or is it green on a coloured monitor?

- Is it showing a border, or just plain green on the entire screen?

Bryce.

[Gryzor]

Welcome! Hope you get it sorted out - the questions Bryce asked are the logical ones to start with...

[ArvaVolente]

Need a bit more info:

- What's it connected to? Is it a green monitor by any chance? Or is it green on a coloured monitor?

- Is it showing a border, or just plain green on the entire screen?

Bryce.

Sorry, yes, it's a green monitor and it shows either a blank screen or a kind of streaky random screen as if it is trying to boot up but the screen hasn't loaded properly.

[Bryce]

Ok. My first suggestion would be to clean the contacts of the power switch in the CPC.

A picture of the "streaky random screen" might help with further diagnosis.

Bryce.

[ArvaVolente]

Sorry about the tardiness of the reply. I had the computer at my homeplace and didn't get there until the weekend just past.

I cleaned the connections like suggested but no difference.

Here are samples of the "streaky" behaviour:
[attach=3][attach=4][attach=5]

Thanks again for your time and patience.

[Bryce]

Ok. Can you tell us which version PCB you have. It should be a number with MC..... printed on the upper side of the main PCB. Or just take a photo of the PCB and post that. I would guess it's the cost-down version with a broken ASIC, if so you may be out of luck.

Bryce.

[TFM]

Hi and welcome!




Looks like a fried ULA (check if it is the old one with metal cooling).

[steve]

If faulty ULAs are a significant problem, then maybe when an FPGA CPC replacement is published, part of the design could be used to make a ULA replacement, with some plus features even.

[Bryce]

Better if it could fit in a CPLD, then it could be a plug-in replacement.

Bryce.