04/11/2021 at 21:30 •
It was the lion kingdom's 1st full size monitor which wasn't a CRT. To someone who lived through the technological adolescence of the 1980's, the original LCD watches, the plasma TV's, passive matrix LCD's, supertwist LCD's, it was still remarkable to see the evolution of all those steps encapsulated in a 4 million pixel sheet of glass.
It was more solid than expected. The flat flex cables didn't disintegrate on contact. Only the logic board had problems.
The glass itself might have been thin & light enough to easily hang on a wall, but a comparably thin backlight would have been a fortune. The best vintage monitor for converting into a picture frame might be the original 30" Apple cinema. It had a separate power supply, which allowed it to be thinner. Then, a $100 investment in a more efficient LED backlight would do the job. It still might be cheaper than a new 2560x1600 monitor. The trick is the LED's have to be purpose built omnidirectional for a TV rather than common strip LED's.
03/30/2021 at 19:32 •
Reconnected all the wires & gave it another go.
This time, the LCD refreshed properly. There was only a slight artifact in black level between the left & right halves. The raspberry pi couldn't reliably restart the X server & show a fullscreen image. It would show a section of an image trucated halfway down the screen. This might have been an intermittent monitor failure.
There's either a bad connection to the logic board or the logic board is on the edge of falling over. It's not the flat flex cables to the glass.
The glass has 16 flat flex cables with bare dies split between 2 identical phenolic resin boards. The artifacts line up with the place where the phenolic boards split. The connectors are high quality with gold contacts & not a speck of dirt.
The logic board had a blown fuse, 10 years ago. It got flaming hot & might just be burned out. It's slightly discolored in the areas which probably got hottest. You can see where identical signals split up between the left & right halves.
The design date brings back memories of when these 30" monitors 1st appeared. They were cutting edge in 2006. Every confuser monitor until then was 27" & smaller. A 30" monitor was like a Steinway to a lion. Lions used to analyze them in the Apple store to get an idea of what the cheaper Dells would look like.
The backlight artifacts were surprisingly hidden as long as there was detail. The grey PLA standoffs surprisingly left artifacts in the lighting. Printing more diffusers & standoffs out of translucent PLA would be the next step.
Even if the logic board proved reliable & the backlight proved good enough, it would be quite a stretch to mount it on a wall. It couldn't face the new monitor because of the glare. The 1 remaneing spot behind the new monitor would be real hard to access. There is a plan to salvage the diffuser & the through hole parts. The diffuser could be used in a 7 segment display.
At the conclusion of this failed experiment, if nothing happened, the original backlight would have still worked. It just had broken farsteners, got flaming hot, burned 150W, & was very dim. It wouldn't have been affordable to run as a picture frame. The backlight couldn't have been replaced for less than the cost of a new monitor. A better lighting system might arrive in the future, but cost money. A reasonable quality LCD picture frame costs money no matter what & can't be had from dumpster parts unless you're Dave Jones.
03/30/2021 at 07:41 •
Reconnected everything & there was obviously a major malfunction.
There's either a dead board, broken wire, or a contaminated connector. The LCD was only driven 1 way instead of oscillating. There were bad columns on 1 side while the other side had good columns. Maybe it could be fixed by checking the voltages, cleaning the connectors or buzzing out a broken wire. The mane problem was the awful backlight. Another $30 for PLA diffusers might make it even, bringing it to $70. Not sure why it had 3 bright bands instead of 16.
The bottom end 32" TV is the $130 1366*768 Sansui. Realistically, as a picture frame, such a drop in resolution wouldn't matter. The lion kingdom is just going to abandon the picture frame instead of buy a TV though.
Anyways, the raspberry pi was underclocked to 400Mhz. It was a lot slower to update this 24 bit 2560x1600 display than 50Mhz UNIX boxes were at updating an 8 bit 1280x1024 display, 30 years ago.
The internet no longer seems to know how to remotely connect to an X server. The X server on raspberry pi's is run with -nolisten tcp which causes it to ignore all connections besides the console. Removing this argument makes it work, but the lion kingdom ended up having to delete lightdm & run X from the command line.
03/10/2021 at 22:47 •
The original backlight had 16 tubes, 25.5" in length.
Other ideas were to just solder together loose LEDs or solder together cool white LED tape instead of RGB tape. The cool white stuff couldn't be repurposed for indoor lighting but would be denser & require a lot less wiring. LED rope wouldn't have a small enough turn radius to be useful & would be dimmer.
A polarizing filter would have to be applied to the front of the glass to make it a reflective backlight. It would be very dim.
The next step was another batch of LED tape.
3 5m rolls, for a total of $16, bringing the project total to $36.
This was cut into 16 horizontal strips & 1 vertical strip. The next problem was creating new conical spacers. The lion kingdom figured it could print 2 to replace the original 10. To avoid spending $20 on a roll of white PLA, the next idea was printing a farstener for some kind of white rod.
To align them properly, finally took the plunge & learned how to draw an alignment pattern in python. It seems rather pointless to learn how to do the same thing in python that lions already did in C, when there was also the java craze, the ruby craze, the node.js craze & the go craze, but python seems to have won the battle to become the jellybean platform independent language. CAD modeling, game programming, machine vision have all standardized on python.
Tested with 1A at 11V.
For standoffs, spending $30 & waiting 2 weeks for white PLA would never do. The lion kingdom took whatever polystyrene hobbylobby had & sharpened it in a pencil sharpener to get new standoffs.
Then, they were hot snotted into some PLA things for farstening to the backlight. It seemed like hot snot would keep them attached. The backlight needed to be a total of 19-20mm behind the glass, but it was really just a guess.
After 2 hours of scotch taping the strips, replacing dead LEDs & repairing jumper cables, it lit up. LEDs started dropping like flies at only 11V. Called it quits after replacing a few LEDS & didn't replace them all.
The camera made it look a lot more even than it was. It was still hideous, uneven & yellow, even with all the diffusion filters on & the standoffs separating everything properly.
A diffuser for each LED strip could be printed out of translucent PLA, for a lot of money. Being just a static picture frame rather than a working monitor, it might be acceptable as is. The next step is to hook everything back up & fire up the raspberry pi.
03/10/2021 at 04:40 •
The mane problem in reviving the ancient monitor is replacing the backlight for less than the cost of a new monitor. The original backlight was well & truly gonsky.
Its plastic supports were crumbled & rattling around, even before the lion kingdom tore it apart.
Accessing the backlight was a gnarly process. The glass had to be taken out of its steel frame. There was no way to reasonably expect it to survive.
Fortunately, the glass survived. Once the CFL tubes were out, it was much easier to access the backlight without taking out the glass. CFL backlight replacements were all extremely expensive. They're intended for 2 tube panels, while the 30" monitor had 16 tubes.
$20 of LED tape was not very satisfying. It needs a way to keep the diffuser separated from the LEDs. The CFL backlight had white cone spacers pressing against the diffuser. If only lions had room to store a roll of white PLA. The LEDs glowed blue when set to white. They would have to be dimmer to really be white.
While taping down the LED tape, a better idea came to mind: LED rope
It would only raise the budget to $40. No-one really knows how to cut LED rope. It can't bend tightly enough to use a single strand.