I have used de-oxit on the edge of the elastomer to pcb contact in the past – very, very sparingly to try and clean the PCB contacts. Then used a piece of stiff card to very very gently push the elastomer in an attempt to clean up the contacts. This tends to work for lines that are blank rather than dim. The line is totally gone in this case either horizontally or vertically and they tend not to repeat.
With lines that are just a little dimmer than the rest I have not found a good solution. If they are paired like this example it implies to me that the driver chips are no longer working properly. The screen is split in two parts driven by the same horizontal chips. So the 1&2 are the same as 33 & 34 lines. As Jeff mentions check the –5V is close to –5V eg –4.89V or higher. The problem is not related to the battery replacement. It is simply the age of the machine, the old LCD displays were prone to heat and moisture problems and of course the chips themselves do age. Don’t be tempted to take the screen apart they are almost impossible to get back together and work – yes I have tried it :) From: M100 <m100-boun...@lists.bitchin100.com<mailto:m100-boun...@lists.bitchin100.com>> on behalf of Jeffrey Birt <bir...@soigeneris.com<mailto:bir...@soigeneris.com>> Reply-To: <m...@bitchin100.com<mailto:m...@bitchin100.com>> Date: Tuesday, February 26, 2019 at 1:17 PM To: <m...@bitchin100.com<mailto:m...@bitchin100.com>> Subject: Re: [M100] Lighter rows of pixels on LCD Hi Andrew, The LCD glass is electrically connected to the PCB via an elastomeric ‘zebra’ strip. This is sort of like a silicone rubber strip with stipes of conductive material embedded to make electrical contact. If something got under between the PCB and zebra strip it might cause an issue like this. The metal frame around the LCD is what applies pressure to hold things in place. You can apply a bit of pressure to the edges to see if it changes. Also, check you power supply voltages. If the -10V for the LCD is low, it could cause problems and perhaps some driver chips would be more sensitive to the low voltage than others? Jeff_Birt (Hey_Birt!) From: M100 <m100-boun...@lists.bitchin100.com<mailto:m100-boun...@lists.bitchin100.com>> On Behalf Of Andrew Kennedy Sent: Tuesday, February 26, 2019 2:42 PM To: m100 <m100@lists.bitchin100.com<mailto:m100@lists.bitchin100.com>> Subject: [M100] Lighter rows of pixels on LCD Hi folks, thanks again for the advice the other day. I just replaced my NiCd, which had a light amount of leakage on the barrel but didn't appear to have reached the PCB. I put a NiMh in there, and the computer is plugged in to charge it up for a while. However, when I turn it on I'm noticing an annoying defect, there are two bars on the screen whose pixels are lighter than the others. The bars are at rows 1&2, and 33&34, counting 0 as the first row. The pixels still turn black, just not as black as the other rows of pixels. I tried searching the mail archives but didn't find any discussion about this. Could it be that the new battery just needs to charge more? I'm going to reseat the ZIF cable, but if there are any other ideas please let me know. - Andrew
