Toshiba T5100 with corrupted text

[falter]

My T5100 has been threatening this on and off.. it'll power up fine but then the text sometimes would turn to gibberish. Today it went full gibberish and is not coming back. The machine seems to be functional and you can tell underneath the garbage the the machine is working.

I found a maintenance manual for it.. im assuming my problem is in the advanced video module.. probably just bad RAM?

 

[eight088]

Do you have access to an external monitor so you can eliminate the built in screen?

 

[falter]

Do you have access to an external monitor so you can eliminate the built in screen?

I only had my Taxan 420 available.. CRT output is all distorted, whereas on the main display, they're fully formed characters, albeit wrong ones. I'm not sure the Taxan can handle whatever resolution the Toshiba screen is operating at.

 

[Conventional Memories]

Hmm sounds like a Vram issue. As for connecting to an external display. Try switching to 350 line mode:

Fn + Down arrow Toggles between 350 and 400 rows in EGA mode

 

[Ruud]

...they're fully formed characters, albeit wrong ones.

Three possibilities IMHO:
- the circuit that writes to the video RAM is bad
- the RAM itself is bad
- the circuit between the RAM and character circuit is bad

An idea: write a program that writes directly to the video RAM, reads it and writes the result to disk. Put the program on a bootable floppy and tell autoexec.bat to execute this program. Read the result on a working PC. This idea can be used for other test programs as well.