Hi,
A week ago I switched on my 4032 to find out that something is wrong with the display. All the spaces are dollar signs and the welcome text has some characters that slowly get drawn on the screen. I see some dots blinking and appearing in some characters. Probably a VRAM and character ROM problem I guess? Is there a way to figure out what is going wrong? I have access to a scope, so I was hoping that I could figure out how the video circuitry works, but I do not want to break any more things.
Here's a screenshot and a video showing the problem:
https://drive.google.com/file/d/1qgppqlp8C5aFiCOIxtX8uSHAQ4V7JCDDDg/view?usp=sharing
https://drive.google.com/file/d/1BAoGq6pr4QeCoQuYJLmIw0A9BNLsDjCRNA/view?usp=sharing
Also, when I switch on the 4032, the time to start up varies a lot. Sometimes it almost immediately comes to life, other times I see a very bright green dot on the middle of the screen for 5 or more seconds before the machine comes to life. As far as I understand, that can be a reset circuit problem?
All the best,
Johan
A week ago I switched on my 4032 to find out that something is wrong with the display. All the spaces are dollar signs and the welcome text has some characters that slowly get drawn on the screen. I see some dots blinking and appearing in some characters. Probably a VRAM and character ROM problem I guess? Is there a way to figure out what is going wrong? I have access to a scope, so I was hoping that I could figure out how the video circuitry works, but I do not want to break any more things.
Here's a screenshot and a video showing the problem:
https://drive.google.com/file/d/1qgppqlp8C5aFiCOIxtX8uSHAQ4V7JCDDDg/view?usp=sharing
https://drive.google.com/file/d/1BAoGq6pr4QeCoQuYJLmIw0A9BNLsDjCRNA/view?usp=sharing
Also, when I switch on the 4032, the time to start up varies a lot. Sometimes it almost immediately comes to life, other times I see a very bright green dot on the middle of the screen for 5 or more seconds before the machine comes to life. As far as I understand, that can be a reset circuit problem?
All the best,
Johan