(Dell M991 CRT) Menu repeatedly appears, buttons act erractic
This monitor has been my project for the past few days. Everything else about it is working beautifully.
First thing I did was replace the lm7805 regulator which feeds the menu-button board. This appears to have fixed the problem for about 24 hours or so... now its come back with a vengeance. pfft... at least I suppose I'm on the right track.
Would a failed storage/decoupling cap have this kind of effect? (at this point I'm thinking theres a loss of stability in the 7805) Maybe adding a heat sink to the regulator (dell didnt place one on it)? Only other possibility I can think of would be altering the resister values along the circuit run from the 7805 to the the buttons then the micro controller (its actually a straight shot, from what I can tell)
I'd appreciate any advice, Thanks in advance
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Re: (Dell M991 CRT) Menu repeatedly appears, buttons act...
Try removing the control panel, and then removing the plastic caps for the buttons. Clean each button cap and it's corresponding hole in the chassis with rubbing alcohol and an old toothbrush. Often, it's just grime, dirt, coffee or orange juice that causes menu buttons to stick.
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I'm assuming the red is gone completely; that is, it's not present at all and not just missing in video from the computer. If that's the case, you probably have a bent pin in the VGA connector, a bad signal cable, or possible video card failure.
The missing red might be due to bad solder connections. These often develop around parts that get hot, like the color output transistors. They also can occur on the circuit board that plugs onto the end of the CRT. If you're comfortable with electronic soldering you could examine the boards and repair any connections that look dodgy (grainy or visibly cracked around the component lead).
It's also possible there's been some component failure, and you won't be able to find that without some test equipment and experience with troubleshooting. It could be the CRT itself that's had it, especially if it's been around a while. Sudden loss of one of the colors is a very common failure mode.
Bottom line is check the soldering if you really want to keep this monitor, but beyond that don't bother repairing it. Not many servicers will work on computer monitors. And the cost of repair is likely to be uneconomical. New LCD monitors are quite inexpensive, and repairing your CRT one may approach replacement cost.
Go to cevice manager and update all monitors and/or visual devices and restart. It's possibly a conflict. You could also try disconnecting a device (the printer is usually the culprit!) and trying again
What sort of shadow lines? I assume you haven't just noticed the two horizontal lines 1/3rd up the screen from the bottom and 1/3rd down from the top from the internal stabilizing wires that all Trinitron CRTs have?
On the front of the monitor is a menu button. Press it, and using the left and right buttons on the monitor navigate through the menus until you see brightness, contrast, etc. Then adjust them as necessary. Steven
My name is Richard; I work for Dell here in Round Rock, Texas. From what you describe, it sounds like the menu button is depressed in such a way that small movement activates its function. I could not suggest any real corrective options as this is most likely a mechanical issue with the button, and would require a technician to open the monitor and inspect that. I am not going to recommend you open the monitor case as it can be dangerous.
I would suggest you call our tech support at 1-800-822-8965 ex. 726-8859, and find out if the monitor is still under warranty.
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