Recovering an Unresponsive Laptop
Every once in a while, someone comes to the TRS-80 Model 100 mailing list asking how to recover a laptop they bought off ebay that is unresponsive to the power button.
-- Clear the RAM File System
Although the Model T laptops use standard AA batteries, understand that there is an internal battery soldered to the motherboard that maintains power to the RAM even when the main batteries are dead or removed.
Often with units that have sat unused for awhile these problems occur:
- the nicad is drained
- the RAM is in some random state
- the contrast knob is in some random state
You need to resolve all three, but you need to do it in the right order. Almost always you can recover a Model T without resorting to more serious troubleshooting.
- Leave the laptop plugged in to the wallcube overnight with Memory Power switch on, and the power off. I don't think it matters whether you have AA's in at this point.
- Let the unit sit with the Memory Power button off and no plug or other cables connected or batteries in the battery compartment for about 15 minutes in order to clear the RAM.
- With the power-button ON, hold down Ctrl-shift-break simultaneously, and hit reset button to clear the RAM
Now fiddle with the contrast knob. Hopefully you will see the normal Model 100 main menu.
-- Checking the Display
In rarer cases, the problem is a bad display, or problematic (internal) display connection. If the "clear RAM" steps above do not resolve the issues, the display is the next thing to check.
To diagnose this problem, after a cold-boot (CTRL-BREAK-Reset), if you hit "Enter" then type "beep" (without quotes) and hit enter again, the machine will make a beep sound if it is actually working (meaning it has a bad LCD or bad LCD connection).
If these steps don't work, then more serious troubleshooting begins. Head over to the Model 100 mailing list (you can subscribe at Model 100 Mailing List