I just got a Samsung SyncMaster 172T 17" LCD on Freecycle and the display would work, but stuck saying ANALOG or just be unresponsive to the front-panel buttons (except power). I opened up and disconnected the button board and the stuck ANALOG went away. Having encounted the same problem on a Dell E171FPb a while back, I popped open the microswitches and used steel wool to clean the slight surface tarnish off the metal discs inside and the contacts below, blew them out well, then put them back together. It works acceptably now.
Disassembly was a little trying. There are two screws on the back near the bottom, accessible if you tilt the stand up. Then you have to snap the black plastic cover off where the stand connects to the monitor. The cover has a big flat area on the back, then it curves around near the bottom. There are two snaps you can press by putting a screwdriver in the slots visible from the bottom, and pressing the snaps away from the monitor. I broke one snap off, and it doesn't matter. With that removed, you can remove the cover and get to three more screws that hold the stand in place. With those out, carefully unplug the bundle from the LCD. I used a thin slot screwdriver at alternating ends of the connector to get it out, to avoid putting stress on the solder connections to the board. With the stand away, you can start snapping the black plastic back off. I started at the bottom, using a slot screwdriver and old credit card to pry the back open and worked my way to the sides, then with them loosened, just hinged it open on the top snaps. With the back removed, unplug the button board and remove it.
Cleaning the microswitches is a delicate operation, as they are small. They have metal covers with snaps at two sides. I used a knife blade to pry one side away so it popped off. Inside is a black plastic disk with bumps on either side, along with a concave metal disk. Flip it over and you should see some discoloration. I used some fairly fine steel wool to clean the bottom of the disk and the contacts inside the switch. For the disk, I placed it on a piece of rubber-like material to grip it, then did some circular motions in place and side-to-side and it didn't slip much. I did similar circular motions in the switch. To avoid bits of steel wool, I blew them out well and crossed my fingers. I was going to clean the power switch, but cut the side with the blade so aborted, since it was working fine anyway. I'm guessing it is a higher-current circuit, so isn't triggered by the oxidation inside. I tested everything before reassembly by putting the LCD face-down half on the edge of a desk, then carefully laying the stand on the back and pugging it all in.
I'm pretty sure these are the same microswitches used in the Dell E171FPb that I had the same problem with last year. Bad caps, bad switches, ugh.
Disassembly was a little trying. There are two screws on the back near the bottom, accessible if you tilt the stand up. Then you have to snap the black plastic cover off where the stand connects to the monitor. The cover has a big flat area on the back, then it curves around near the bottom. There are two snaps you can press by putting a screwdriver in the slots visible from the bottom, and pressing the snaps away from the monitor. I broke one snap off, and it doesn't matter. With that removed, you can remove the cover and get to three more screws that hold the stand in place. With those out, carefully unplug the bundle from the LCD. I used a thin slot screwdriver at alternating ends of the connector to get it out, to avoid putting stress on the solder connections to the board. With the stand away, you can start snapping the black plastic back off. I started at the bottom, using a slot screwdriver and old credit card to pry the back open and worked my way to the sides, then with them loosened, just hinged it open on the top snaps. With the back removed, unplug the button board and remove it.
Cleaning the microswitches is a delicate operation, as they are small. They have metal covers with snaps at two sides. I used a knife blade to pry one side away so it popped off. Inside is a black plastic disk with bumps on either side, along with a concave metal disk. Flip it over and you should see some discoloration. I used some fairly fine steel wool to clean the bottom of the disk and the contacts inside the switch. For the disk, I placed it on a piece of rubber-like material to grip it, then did some circular motions in place and side-to-side and it didn't slip much. I did similar circular motions in the switch. To avoid bits of steel wool, I blew them out well and crossed my fingers. I was going to clean the power switch, but cut the side with the blade so aborted, since it was working fine anyway. I'm guessing it is a higher-current circuit, so isn't triggered by the oxidation inside. I tested everything before reassembly by putting the LCD face-down half on the edge of a desk, then carefully laying the stand on the back and pugging it all in.
I'm pretty sure these are the same microswitches used in the Dell E171FPb that I had the same problem with last year. Bad caps, bad switches, ugh.