Ang: Re: Need help with messed up C128...

From: Mikael Holm (
Date: 2003-02-07 09:46:18

Hej Spiro and all...

I also read further down in Ray's document that a faulty power supply 
could cause this malfunction... Is this correct? 

I will test the computer with another power supply first, before trying to 
find out how to look for shortings with a multimeter... (Mainly because I 
don't know much about how to do that...) 

Mikael Holm

Hello Mikael,

Mikael Holm wrote:
> I just received a C128 (220v PAL) and when I powered it up it just 
> displays garbage on screen. All it displays is some random graphics (not 

> really characters, but rather strange patterns) with different text and 
> background colors. And all this is flashing and changing. And it won't 
> to C64-mode when I hold down the C=-key while turning the power on.

> U11       315012-01 (8721) PLA (Programable Logic Array) 
>      No bootup in any mode. In 40 columns: blank screen, white screen, 
> light blue screen (no border), random checkerboard pattern or flashing 
> "garbage" characters. 

That could be the problem.

> U18       390059-01 CHARACTER ROM
>      No characters. Startup has border, but "garbage" where characters 
> belong, or entire area inside border just lines or blocks. 

I don't think so, since C= (for 64-mode) does not work, either. If it
just were the character ROM, this would have to work.

I would go for U11, but before doing so, I would go with a multimeter
and look for shortings between the various address- and data-lines
available at the processor.


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