How to repair a dim display on the K1000 K1200 Keyboards and the 1000PX and other Expanders
Update 2013: Amost all of this section is obsolete because the EL back lit displays are no longer built - being replaced by LED backlit displays. See Display with LED for details on what to use and how to install these displays. There are other options for those who have some mechanical skills and electronics knowledge. For one of these options using an OLED or VFD (Vacuum Fluorescent Display) go to the users group (you must join to see the pictures) and search for the discussions for "who needs a backlit display" dated around 3/31/2011 to 4/5/2011. The photos of this option were uploaded to the site on 4/4/2011 and are named "LCD Upgrade to OLED or VFD".
Here you will find information about how (we used to) to fix a display that is dim. The EL (Electro luminescent) back lights' brightness degrades over time especially if the power is left on. The units typically last 1000 to 4000 hours with power applied. To extend the life of your back light, turn the power to your unit off when you are not using it. Thanks to Andrea Toni (and others) for the source information (back in 2004)! Also thanks to Tomohito for his details on building a backlight panel.
Overview: All of the keyboards and modules use the same basic display.Here are the ways to approach your display upgrade or repair:
A Choice: Find a repair shop to do it for you - look to spend upwards of $100 even if you purchase the parts.
An Unlikely Choice: Buy the complete assembly and
replace it. It has to be a 16x2 LCD matrix with character
5x7 dots + cursor and the most important thing are the dimensions - it
really has to be 85 cm x 30 cm x 10.1 cm and the viewing area has to be
64 x 14 cm to fit without mechanical modifications.
Third Choice:. Disassemble the display and replace only the back light. You have different options if you take this approach.
1. You could use an EL panel from a purchased
If you remove the frame and LCD screen, be careful. The LDC screen connects to the circuit board with what looks like two rubber strips. These are really connectors that make around 100 contacts. You must place the LCD screen and these connectors exactly in the same location when you replace the LCD screen. And, keep track of the 'top' versus 'bottom' of the screen. If you place it upside down, your display will seem to work except letters will be scrambled (or other funny things will happen). Here are pictures of the display mounted to the PC board correctly -and upside down.
2. You can also build your own strip. This may eventually be the best way to get a bright display because the display back light EL panels have a limited shelf life. That is, it will glow dimmer over time even if power is not applied. If you purchase a surplus display or one that has been stored for many years it may not have a bright back light. This is a real bummer but no other options seem to exist if new display units eventually disappear from the market.
We would love to find a source for the just back light panel that fits the display unit. It would need to be around 20mm wide by 70mm long < 1mm thick - with solder tabs at one end centered and 4 mm apart. If you found one with solder tabs 4mm apart that was too large - it might be possible to cut the panel to size. Let us know if you find any such products.
You can make your own panel. Purchase some EL sheet, cut it to size, then attach some solder tabs. The solder tabs are the difficult part. You have to expose the foil on the back and front side of the strip and make a connection. A solder type epoxy seems to work best.
Some suppliers of EL sheet and panels are:
If you find other sources, let the group know, we will add the source to this list.
I will add pics from alzerom site later.