You may have already checked but make sure the –5V is good and that the contrast pot is working sometimes they do not work so the screen is in low contrast mode = not visible but still working. You should be able to see the screen go almost entirely black as you turn the contrast pot or the menu might appear :)
Buzz out all the connections to the LCD header make sure no other trace has been damaged by a capacitor leak, it is possible to miss a break. Make sure the connection onto the LCD is good and no corrosion has happened due to capacitors out gassing. I have had a trace corrode under one of the caps that caused the screen to stop working. The fact it beeps is a good sign it means the keyboard interface seems to be working, some of the same chips drive the LCD so they are probably good. From: M100 <[email protected]<mailto:[email protected]>> on behalf of Nathan Misner <[email protected]<mailto:[email protected]>> Reply-To: <[email protected]<mailto:[email protected]>> Date: Saturday, July 21, 2018 at 1:53 PM To: <[email protected]<mailto:[email protected]>> Subject: [M100] Model 100 LCD doesn't work I'm having a problem with my TRS-80 Model 100 where the LCD doesn't function, but the computer is otherwise operating (if I type "beep" into BASIC, it works, etc.). I replaced all of the capacitors on the board that I had replacements for (everything but C103 and C82) and fixed a broken trace I saw (a leaky capacitor had corroded the trace between the negative side of C85 and D15, so I soldered a jumper wire on the back of the board) but the display still doesn't work. If anyone has any suggestions for getting it going, I'd greatly appreciate it. Thanks, Nathan
