I repaired my LCD monitor!

[RobbieThe1st]

Well, about a month or so ago, I go to get onto the computer, turn it on, look away for a couple minutes, and when I look back, the monitor appears to be off. I flip the screen off, then on, and it comes on... then dies two seconds later.

Near as I can figure out, some part in the backlight-power supply failed - It would start the lights up, but couldn't maintain the voltage needed to run the lights, and so it flipped back off again.

Anyway, I took the screen completely and absolutely apart, down to the individual bits of the LCD itself, and after fiddling around, ended up duct-taping a fluorescent light to the back of it.  It worked... sort of. Not nearly bright enough, and not the right color.
Also, in the process of taking it apart, I ended up breaking one of the four CCL(Cold Cathode Lamp) backlights - a whole chunk about as wide as the nail on my pinky simply gone!
Note that when I tested it a little bit later, it, amazingly, still worked!

So, anyway, after more testing and such, I ended up looking up a tutorial on how to replace CCL's, and ended up ordering two packs of 12" CCL computer lights. I figured to replace the lights, and run the new inverters off a line into my PC - clumsy, but it would work fine.

Two weeks ago or so, the lights came, and after losing one thing or another, ended up doing nothing.

Yesterday, I got everything out, and started carefully taking the LCD apart again, and got it completely apart, then put it together with the old lamps, and tested it - same thing, and all four bulbs still lit.

Well, to make a long story short, today I took everything apart and cleaned every layer as carefully as I could. I had a big problem with dust as dad's comp was right next to me, blowing dust everywhere... It took me a long time to get things put back together cleanly.

After testing stuff, then wiring and all sorts of other things, I finally had a working monitor.

This is what the back looks like now:


The wood and metal on the left side are my custom lap-desk, which the monitor goes into.

At the upper left, the bit of black with a bit of red sticking out, and red/yellow wires going into is my on/off switch for the new backlight.

The blue box is one of two inverters, converting 12VDC into ~650V chopped DC.
The red/black wire going into the middle(right) goes to the second inverter, inside the monitor's case.

The two twisted black/green wires coming out of the middle and going to the left bottom and away are the power wires - Originally Christmas-light wires.


Note that I have the 12V input plugged not into my computer, as I origionally figured on doing, but into a RadioShack 13.8VDC/3AMP power supply - I found that 12.0V didn't provide a high enough voltage for the lights in my display - even now its a tad dim, I will later attempt to raise the voltage a tad more.

What do you think?


-RobbieThe1st


 

[lucas marcone]

i thonk you're a brave man for takeing apart the monitor in the first place. i also think you crazy for useing christmas light wires....then again i know absofrigginlutely about what you did to it....i've never learned how to fix electronics

[Tapewolf]

I congratulate you.  Too many people would just chuck the thing away.
On Friday I managed to fix someone's tape deck on another board.  The long and boring story, I can tell if anyone is curious.  The fix itself was quite bizarre... one of the parts was missing so he drew a replacement using a marker pen and some sticky labels.

[Eibborn]

Well done- I'd have no idea where to even begin. I am impressed!

[Joe3210]

Good job.  Anybody else would have bought another moniter.

[RobbieThe1st]

I congratulate you.  Too many people would just chuck the thing away.
On Friday I managed to fix someone's tape deck on another board.  The long and boring story, I can tell if anyone is curious.  The fix itself was quite bizarre... one of the parts was missing so he drew a replacement using a marker pen and some sticky labels.

Well, without attempting to sound *too* eager, I would love to hear the story.

Thanks!


-RobbieThe1st

[Tapewolf]

Well, without attempting to sound *too* eager, I would love to hear the story.

Okay.  This is one of my machines, but it's identical to the faulty one.


http://i89.photobucket.com/albums/k216/tapewolf/tape/S7300121.jpg


The original thread is here, but I have a suspicion you need to be a member of the board to see it, so I'll paraphrase it below.

Basically, the guy had just got one of these, and he had two problems - firstly, when he played a tape, the machine would just keep playing and never stop, and secondly, the tape counter wasn't changing.

So I asked him this:

"Is the capstan turning? This is the silvery post just to the right of the head block, the one above the rubber pinch-roller. The capstan will only turn when a tape is loaded, or if you push the right-hand tension arm upwards.

Secondly, on the left-hand side of the TSR-8 is a roller with a black, grooved rubber tread. This roller controls the counter, and I believe the microprocessor also uses it as a reference for tape motion. If this has stopped working, you could get some quite odd effects.  You might try rotating it by hand a couple of times, to see if it changes, but be aware that the counter will only increment when the capstan is turning."

To which he replied:

"About the capstan, I've done tests again, and yes, it is turning when I'm playing the tape. But still displaying 00:00:00 all the time."

"Right," I said.  "That would suggest that the tach roller has failed somehow. This is the left one with the grooved rubber coating.  What is supposed to happen is that it rotates a coloured disk between a pair of photosensors. Probably two pairs actually, so it can sense the direction as well, but I haven't disassembled that far. As the disk rotates it will detect the change in brightness and use it to determine the tape speed. This might be mechanical, e.g. the disk has come off or is not rotating, or it could be that the photosensors have failed."

At that point I began to wonder if there was a way for him to test them without using an oscilloscope and other test gear.  Then I remembered a neat little trick with a camera:

"Find out if the light sources are working. These are probably infrared LEDs, which you can't normally see with the naked eye. However, if you have a camcorder with a preview screen (a cellphone with camera may work), you may well find that it can see them. Try this with a TV remote first - point it at the camera and press the buttons, to make sure that it can see them light up. If it does work with the remote (and not all cameras do), try running the machine with the front cover off and the tach roller removed, and see if the sensors light up."

It turned out that the lightsources were working, but when he took the roller off:
"What I see is a bright surface, with two small (rests?) of old stick. Is it supposed to have a coloured surface or something?  If so, I guess the problem is here: it's been removed! Do you think I can do it myself from a model?"

"It might be worth trying," I said, "Or you could see if you can get one from a TEAC parts dealer. I actually have a couple of spare ones I bought last year for my parts cache - I think they're stickers. I can scan one in as a pattern if you like.
What you might want to try quickly as a stopgap measure is using black marker on some sticky labels. The black bits need to be matt I suspect, and it's probably best if you leave the rest silver."


http://i89.photobucket.com/albums/k216/tapewolf/tape/plateguide.jpg

Later on he posted this:

"It works!  I've done new stickers with 3 black (and I left the rest of the iron surface untouched). I consider this as a "quick hack" and I'll order the official parts, for sure. Anyway, it seems to work perfectly now!"

...so there you have it.  The counter's probably counting in 5/7ths of a second or something weird like that, but it got him going 

[llearch n'n'daCorna]

It's totally readable, even if you don't log in. Just in case you were wondering. ;-]