04/04/2021

I'm a lucky owner of Atari STBooks, however not all of them worked perfectly.

Problem: This particular one didn't do anything when switched on, the LCD Bias voltage that is an adjustable negative 12-17V was around +0.222V, that is the standby voltage. Every time I started the laptop the bias went to down to around -0.9V but then went back to the 0.222V. The circuit was not able to start.

This laptop came to me as repaired and modified, so it was obvious to check those first. This time it was easy to find the problematic element, a 1mH inductor (L1003) that was a wrong replacement of the original.

After replacing the inductor it came back to life but bombed out (4 bombs). This is due to a (certain version) TOS bug, that stops the STBook from booting when the HDD is not detected. So I removed the installed and failing ugly CF adapters and mods, replaced it with a fresh CF that I prepared in my Falcon.

This STBook is now fully working again.

The STBook's board

Almost there...

Back in business after CF-IDE replacement hard drive

Video of the STBook booting from CF-IDE