Is my LCD toast?
Roger Lee
Posts: 339
have a parallax 4x20 serial LCD (#27979).
all I can get now is all pixels in row 0 (top row) and row 2 on all the time.
Even the default test does not work. I have to assume it is "baked", but I just don't want to.
I used it for about 2 days with prop 40 pin DIP on breadboard and also with prop proto board.
I think I was only making software changes when it stopped, as my circuit was working fine.
Am looking for possible cause so I don't do it again.
Roger
all I can get now is all pixels in row 0 (top row) and row 2 on all the time.
Even the default test does not work. I have to assume it is "baked", but I just don't want to.
I used it for about 2 days with prop 40 pin DIP on breadboard and also with prop proto board.
I think I was only making software changes when it stopped, as my circuit was working fine.
Am looking for possible cause so I don't do it again.
Roger
Comments
Row 1 & 2 pixels that are always on, sounds more like it is operating in "1-line" mode (2 lines displayed on a 4 X 20 LCD) with the contrast adjustment pot turned all the way to max. With the pixels "all on" characters may be displayed, but will be invisible due to every pixel being black.
Turn the contrast down until the pixels are barely visible, or just invisible, and any displayed characters should become visible.
I haven't used Parallax's serial LCD, so if the above doesn't help, hopefully someone who is more familiar, can reply back with more specific info.
Good luck
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This post is a work of art. Variations in spelling and grammar are intentional, artistic endeavors that add value to all of mankind.
Looks like R.I.P is the word for this display.
When I damage components I can usually point to the cause. Don't have a clue in this case.
You should call Tech Support and see if they can help you first before you
write this Display off that it dose not work
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··Thanks for any·
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Sam
Static electrical build up is typically at it's worst during winter, so practicing ESD safe handling of parts is especially important.
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This post is a work of art. Variations in spelling and grammar are intentional, artistic endeavors that add value to all of mankind.
Brian218 That can never be stressed enough. Static = Bad
Don't have a good system for that. OK, Don't have any anti static system at all.
Whatever the cause this time thanks for the reminder.
Static is indeed very bad. One of my many job titles is ESD Coordinator, and very few people give ESD the respect its due.
60 to 90% of most consumer electronic failures are caused by ESD damage.
Most people, can not feel a static charge of less than 2000 volts. Keep in mind some components can be damaged by less than 100 volts of static electricity.
I think it would be very helpful for Parallax to post a sticky topic on safe ESD handling of their products.
Meanwhile I'll try to put together some info on ESD and will make a separate post a little later.
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This post is a work of art. Variations in spelling and grammar are intentional, artistic endeavors that add value to all of mankind.
Angled LCD mount.· I remember how Russ Johnson Ferguson, who hasn't been around posted in a long time come to think of it,·had placed his LCD in an acrylic picture frame, the kind that holds two pics,·looked pretty handy.· As I recall, he posted a pic of it, too.· (See OfficeDepot, Target, etc)
Post Edited (PJ Allen) : 12/31/2008 8:55:39 PM GMT
In my case, I purchased a local Hitachi compatible LCD that was exactly the same as the Parallax product - except Vdd and Vcc were reversed.{Why manufacturers do such things I'll never know!} This is a very subtle difference for the average beginner. But points out that polarity is ALWAYS a critical assembly and wiring issue.
The cause of the failure was a mere momentary application of reverse polarity. I noticed the problem because I was holding it while I powered up and it suddenly got quite hot. I immediately removed power, but after that all I got was a screen full of black tiles. I suspect that may be caused by wiping out the memory side of the unit. It may be the most sensitive part.
Remedy? Obviously verify documentation for your unit and double check power hook ups. But I think that actually having diode protection or a polarized power plug might also be helpful.
This also taught me that holding a unit while powering up is a good way to monitor any unusual heat.
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How do you like my name change?
aka G. Herzog [noparse][[/noparse] 黃鶴 ] in Taiwan
Post Edited (Loopy Byteloose) : 1/1/2009 11:59:25 AM GMT